WorldWideScience

Sample records for brillouin scattering and spectra

  1. A feature extraction method of the particle swarm optimization algorithm based on adaptive inertia weight and chaos optimization for Brillouin scattering spectra

    Science.gov (United States)

    Zhang, Yanjun; Zhao, Yu; Fu, Xinghu; Xu, Jinrui

    2016-10-01

    A novel particle swarm optimization algorithm based on adaptive inertia weight and chaos optimization is proposed for extracting the features of Brillouin scattering spectra. Firstly, the adaptive inertia weight parameter of the velocity is introduced to the basic particle swarm algorithm. Based on the current iteration number of particles and the adaptation value, the algorithm can change the weight coefficient and adjust the iteration speed of searching space for particles, so the local optimization ability can be enhanced. Secondly, the logical self-mapping chaotic search is carried out by using the chaos optimization in particle swarm optimization algorithm, which makes the particle swarm optimization algorithm jump out of local optimum. The novel algorithm is compared with finite element analysis-Levenberg Marquardt algorithm, particle swarm optimization-Levenberg Marquardt algorithm and particle swarm optimization algorithm by changing the linewidth, the signal-to-noise ratio and the linear weight ratio of Brillouin scattering spectra. Then the algorithm is applied to the feature extraction of Brillouin scattering spectra in different temperatures. The simulation analysis and experimental results show that this algorithm has a high fitting degree and small Brillouin frequency shift error for different linewidth, SNR and linear weight ratio. Therefore, this algorithm can be applied to the distributed optical fiber sensing system based on Brillouin optical time domain reflection, which can effectively improve the accuracy of Brillouin frequency shift extraction.

  2. Unifying Brillouin scattering and cavity optomechanics

    CERN Document Server

    Van Laer, Raphaël; Baets, Roel; Van Thourhout, Dries

    2015-01-01

    So far, Brillouin scattering and cavity optomechanics were mostly disconnected branches of research. Both deal with photon-phonon coupling, but a number of differences impeded their unambiguous fusion. Here, we reveal a close connection between two parameters of central importance in these fields: the Brillouin gain coefficient $\\tilde{\\mathcal{G}}$ and the zero-point optomechanical coupling rate $g_{0}$. In addition, we derive the dynamical cavity equations from the coupled-mode description of a Brillouin waveguide. This explicit transition shows the unity of optomechanical phenomena, such as stimulated Brillouin scattering and electromagnetically induced transparency, regardless of whether they occur in waveguides or in resonators. Therefore, the fields can no longer be disentangled. We propose an experimental manifestation of the link in silicon photonic nanowires.

  3. Unifying Brillouin scattering and cavity optomechanics

    Science.gov (United States)

    Van Laer, Raphaël; Baets, Roel; Van Thourhout, Dries

    2016-05-01

    So far, Brillouin scattering and cavity optomechanics have been mostly disconnected branches of research, although both deal with photon-phonon coupling. This begs for the development of a broader theory that contains both fields. Here, we derive the dynamics of optomechanical cavities from that of Brillouin-active waveguides. This explicit transition elucidates the link between phenomena such as Brillouin amplification and electromagnetically induced transparency. It proves that effects familiar from cavity optomechanics all have traveling-wave partners, but not vice versa. We reveal a close connection between two parameters of central importance in these fields: the Brillouin gain coefficient and the zero-point optomechanical coupling rate. This enables comparisons between systems as diverse as ultracold atom clouds, plasmonic Raman cavities, and nanoscale silicon waveguides. In addition, back-of-the-envelope calculations show that unobserved effects, such as photon-assisted amplification of traveling phonons, are now accessible in existing systems. Finally, we formulate both circuit- and cavity-oriented optomechanics in terms of vacuum coupling rates, cooperativities, and gain coefficients, thus reflecting the similarities in the underlying physics.

  4. Stimulated Brillouin scattering and Brillouin-coupled four-wave-mixing in a silica microbottle resonator

    CERN Document Server

    Asano, Motoki; Özdemir, Şahin Kaya; Ikuta, Rikizo; Yang, Lan; Imoto, Nobuyuki; Yamamoto, Takashi

    2016-01-01

    We report the first observation of stimulated Brillouin scattering (SBS) with Brillouin lasing, and Brillouin-coupled four-wave-mixing (FWM) in an ultra-high-Q silica microbottle resonator. The Brillouin lasing was observed at the frequency of $\\Omega_B=2\\pi\\times10.4$ GHz with a threshold power of $0.45$ mW. Coupling between Brillouin and FWM was observed in both backward and forward scattering directions with separations of $2\\Omega_B$. At a pump power of $10$ mW, FWM spacing reached to 7th and 9th order anti-Stokes and Stokes, respectively.

  5. Brillouin scattering, piezobirefringence, and dispersion of photoelastic coefficients of CdS and ZnO

    DEFF Research Database (Denmark)

    Berkowicz, R.; Skettrup, Torben

    1975-01-01

    We have measured the dispersion of the Brillouin scattering from acoustoelectrical domains in CdS and ZnO. These spectra are compared with the birefringence spectra obtained by applying uniaxial stress. The resonant cancellation of the Brillouin scattering occurs at the spectral position of the i......We have measured the dispersion of the Brillouin scattering from acoustoelectrical domains in CdS and ZnO. These spectra are compared with the birefringence spectra obtained by applying uniaxial stress. The resonant cancellation of the Brillouin scattering occurs at the spectral position...... of the isotropic point of the stress-induced birefringence. From these spectra it is concluded that the Brillouin scattering in CdS and ZnO is determined by elasto-optic effects alone. The spectra of some of the photoelastic coefficients have been determined. A model dielectric constant is derived where both....... It is found that the exchange interaction between the excitons may change the values of the photoelastic coefficients in ZnO about 10%....

  6. Stimulated Brillouin scattering revisited: Strong coupling regime and Rabi splitting

    CERN Document Server

    Huy, Kien Phan; Tchahame, Joel Cabrel; Sylvestre, Thibaut

    2015-01-01

    Stimulated Brillouin scattering in optical waveguides is a fundamental interaction between light and acoustic waves mediated by electrostriction and photoelasticity. In this paper, we revisit the usual theory of this inelastic scattering process to get a joint system in which the acoustic wave is strongly coupled to the interference pattern between the optical waves. We show in particular that, when the optoacoustic coupling rate is comparable to the phonon damping rate, the system enters in the strong coupling regime, giving rise to avoided crossing of the dispersion curve and Rabi-like splitting. We further find that optoacoustic Rabi splitting could in principle be observed using backward stimulated Brillouin scattering in sub-wavelength diameter tapered optical fibers with moderate peak pump power.

  7. Stimulated Brillouin Scattering Microscopic Imaging.

    Science.gov (United States)

    Ballmann, Charles W; Thompson, Jonathan V; Traverso, Andrew J; Meng, Zhaokai; Scully, Marlan O; Yakovlev, Vladislav V

    2015-01-01

    Two-dimensional stimulated Brillouin scattering microscopy is demonstrated for the first time using low power continuous-wave lasers tunable around 780 nm. Spontaneous Brillouin spectroscopy has much potential for probing viscoelastic properties remotely and non-invasively on a microscopic scale. Nonlinear Brillouin scattering spectroscopy and microscopy may provide a way to tremendously accelerate the data aquisition and improve spatial resolution. This general imaging setup can be easily adapted for specific applications in biology and material science. The low power and optical wavelengths in the water transparency window used in this setup provide a powerful bioimaging technique for probing the mechanical properties of hard and soft tissue.

  8. Stimulated Brillouin Scattering Microscopic Imaging

    Science.gov (United States)

    Ballmann, Charles W.; Thompson, Jonathan V.; Traverso, Andrew J.; Meng, Zhaokai; Scully, Marlan O.; Yakovlev, Vladislav V.

    2015-12-01

    Two-dimensional stimulated Brillouin scattering microscopy is demonstrated for the first time using low power continuous-wave lasers tunable around 780 nm. Spontaneous Brillouin spectroscopy has much potential for probing viscoelastic properties remotely and non-invasively on a microscopic scale. Nonlinear Brillouin scattering spectroscopy and microscopy may provide a way to tremendously accelerate the data aquisition and improve spatial resolution. This general imaging setup can be easily adapted for specific applications in biology and material science. The low power and optical wavelengths in the water transparency window used in this setup provide a powerful bioimaging technique for probing the mechanical properties of hard and soft tissue.

  9. Brillouin scattering induced transparency and non-reciprocal light storage

    CERN Document Server

    Dong, Chun-Hua; Zou, Chang-Ling; Zhang, Yan-Lei; Fu, Wei; Guo, Guang-Can

    2014-01-01

    Stimulated Brillouin scattering (SBS) is a very fundamental interaction between light and travelling acoustic waves, which is mainly attributed to the electrostriction and photoelastic effects with the interaction strength being orders of magnitude larger than other nonlinearities. Although various photonic applications for all-optical light controlling based on SBS have been achieved in optical fiber and waveguides, the coherent light-acoustic interaction remains a challenge. Here, we experimentally demonstrated the Brillouin scattering induced transparency (BSIT) in a high quality optical microresonantor. Benefited from the triple-resonance in the whispering gallery cavity, the photon-phonon interaction is enhanced, and enables the light storage to the phonon, which has lifetime up to 10us. In addition, due to the phase matching condition, the stored circulating acoustic phonon can only interact with certain direction light, which leads to non-reciprocal light storage and retrieval. Our work paves the way t...

  10. Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering.

    Science.gov (United States)

    Klieber, Christoph; Hecksher, Tina; Pezeril, Thomas; Torchinsky, Darius H; Dyre, Jeppe C; Nelson, Keith A

    2013-03-28

    This paper presents and discusses the temperature and frequency dependence of the longitudinal and shear viscoelastic response at MHz and GHz frequencies of the intermediate glass former glycerol and the fragile glass former tetramethyl-tetraphenyl-trisiloxane (DC704). Measurements were performed using the recently developed time-domain Brillouin scattering technique, in which acoustic waves are generated optically, propagated through nm thin liquid layers of different thicknesses, and detected optically after transmission into a transparent detection substrate. This allows for a determination of the frequency dependence of the speed of sound and the sound-wave attenuation. When the data are converted into mechanical moduli, a linear relationship between longitudinal and shear acoustic moduli is revealed, which is consistent with the generalized Cauchy relation. In glycerol, the temperature dependence of the shear acoustic relaxation time agrees well with literature data for dielectric measurements. In DC704, combining the new data with data from measurements obtained previously by piezo-ceramic transducers yields figures showing the longitudinal and shear sound velocities at frequencies from mHz to GHz over an extended range of temperatures. The shoving model's prediction for the relaxation time's temperature dependence is fairly well obeyed for both liquids as demonstrated from a plot with no adjustable parameters. Finally, we show that for both liquids the instantaneous shear modulus follows an exponential temperature dependence to a good approximation, as predicted by Granato's interstitialcy model. PMID:23556795

  11. Bursting behaviours in cascaded stimulated Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang

    2012-01-01

    Stimulated Brillouin scattering is studied by numerically solving the Vlasov-Maxwell system.A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma.It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light,as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction.The bursting time in the reflectivity is found to be less than half the ion acoustic period.The ion temperature can affect the stimulated Brillouin scattering cascade,which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures.For stimulated Brillouin scattering saturation,higher-harmonic generation and wave-wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter.In addition,stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light.

  12. Unconventional physical mechanisms between stimulated Brillouin scattering and backward stimulated Raman scattering in liquid water

    International Nuclear Information System (INIS)

    In this paper, the stimulated Brillouin scattering (SBS) and the backward stimulated Raman scattering (BSRS) excited by a focused Gaussian laser in liquid water with different attenuation coefficients are investigated experimentally. Experimental results indicate that the relationships between SBS and BSRS are not merely competitive; the former has an obvious amplifying effect on the latter. Also, two different physical mechanisms were discussed in order to explain these phenomena

  13. Brillouin scattering self-cancellation

    Science.gov (United States)

    Florez, O.; Jarschel, P. F.; Espinel, Y. A. V.; Cordeiro, C. M. B.; Mayer Alegre, T. P.; Wiederhecker, G. S.; Dainese, P.

    2016-06-01

    The interaction between light and acoustic phonons is strongly modified in sub-wavelength confinement, and has led to the demonstration and control of Brillouin scattering in photonic structures such as nano-scale optical waveguides and cavities. Besides the small optical mode volume, two physical mechanisms come into play simultaneously: a volume effect caused by the strain-induced refractive index perturbation (known as photo-elasticity), and a surface effect caused by the shift of the optical boundaries due to mechanical vibrations. As a result, proper material and structure engineering allows one to control each contribution individually. Here, we experimentally demonstrate the perfect cancellation of Brillouin scattering arising from Rayleigh acoustic waves by engineering a silica nanowire with exactly opposing photo-elastic and moving-boundary effects. This demonstration provides clear experimental evidence that the interplay between the two mechanisms is a promising tool to precisely control the photon-phonon interaction, enhancing or suppressing it.

  14. Brillouin Scattering Self-Cancellation

    CERN Document Server

    Florez, Omar; Espinel, Yovanny A V; Cordeiro, Cristiano M B; Alegre, Thiago P Mayer; Wiederhecker, Gustavo S; Dainese, Paulo

    2016-01-01

    The interaction between light and acoustic phonons is strongly modified in sub-wavelength confinement, and has led to the demonstration and control of Brillouin scattering in photonic structures such as nano-scale optical waveguides and cavities. Besides the small optical mode volume, two physical mechanisms come into play simultaneously: a volume effect caused by the strain induced refractive index perturbation (known as photo-elasticity), and a surface effect caused by the shift of the optical boundaries due to mechanical vibrations. As a result proper material and structure engineering allows one to control each contribution individually. In this paper, we experimentally demonstrate the perfect cancellation of Brillouin scattering by engineering a silica nanowire with exactly opposing photo-elastic and moving-boundary effects. This demonstration provides clear experimental evidence that the interplay between the two mechanisms is a promising tool to precisely control the photon-phonon interaction, enhancin...

  15. A systematic study of Rayleigh-Brillouin scattering in air, N2 and O2 gases

    CERN Document Server

    Gu, Ziyu

    2014-01-01

    Spontaneous Rayleigh-Brillouin scattering experiments in air, N2 and O2 have been performed for a wide range of temperatures and pressures at a wavelength of 403 nm and at a 90 degrees scattering angle. Measurements of the Rayleigh-Brillouin spectral scattering profile were conducted at high signal-to-noise ratio for all three species, yielding high-quality spectra unambiguously showing the small differences between scattering in air, and its constituents N2 and O2. Comparison of the experimental spectra with calculations using the Tenti S6 model, developed in 1970s based on linearized kinetic equations for molecular gases, demonstrates that this model is valid to high accuracy. After previous measurements performed at 366 nm, the Tenti S6 model is here verified for a second wavelength of 403 nm. Values for the bulk viscosity for the gases are derived by optimizing the model to the measurements. It is verified that the bulk viscosity parameters obtained from previous experiments at 366 nm, are valid for wavel...

  16. Ferroelectric Phase Transition and Photoinduced Cooperative Phenomena in Bi-Layered Perovskite Pb2Bi4Ti5O18 Ceramics Studied by Brillouin Scattering

    Science.gov (United States)

    Takesada, Masaki; Ueki, Ayaka; Onodera, Akira; Noguchi, Yuji; Miyayama, Masaru

    2010-09-01

    The ferroelectric phase transition mechanism and ultraviolet (UV) photoexcition effect have been investigated in the bismuth layered perovskite Pb2Bi4Ti5O18 by Brillouin scattering using a Sandercock-type tandem Fabry-Perot interferometer. The temperature dependences of Brillouin spectra both with and without UV irradiation were observed around phase transition points. The observed Brillouin spectra include a central peak component that shows an anomaly in the ferroelectric phase transition point TC=450 K. The central peak spectra show narrowing under UV irradiation. The correlation length of the ferroelectric dipole fluctuation should be enhanced with the UV irradiation effect below TC.

  17. Collective stimulated Brillouin scatter

    CERN Document Server

    Korotkevich, Alexander O; Rose, Harvey A

    2011-01-01

    We develop a statistical theory of stimulated Brillouin backscatter (BSBS) of a spatially and temporally partially incoherent laser beam for laser fusion relevant plasma. We find a new collective regime of BSBS which has a much larger threshold than the classical threshold of a coherent beam in long-scale-length laser fusion plasma. We identify two contributions to BSBS convective instability increment. The first is collective with intensity threshold independent of the laser correlation time and controlled by diffraction. The second is independent of diffraction, it grows with increase of the correlation time and does not have an intensity threshold. The instability threshold is inside the typical parameter region of National Ignition Facility (NIF). We also find that the bandwidth of KrF-laser-based fusion systems would be large enough to allow additional suppression of BSBS.

  18. Enhanced Simultaneous Distributed Strain and Temperature Fiber Sensor Employing Spontaneous Brillouin Scattering and Optical Pulse Coding

    OpenAIRE

    Soto, M. A.; Bolognini, G.; Di Pasquale, F.

    2009-01-01

    In this work, we propose the use of optical pulse coding techniques for simultaneous strain and temperature sensing based on spontaneous Brillouin scattering. Optical pulse coding provides a significant receiver signal-to-noise ratio enhancement, allowing for accurate Brillouin intensity and frequency shift measurements at low peak power levels. Due to the cross-sensitivity of these two parameters on both temperature and strain, optical pulse coding improves the temperature and strain resolut...

  19. The broad Brillouin doublet and CP of KTaO3, second sound vs. Two-phonon difference scattering

    International Nuclear Information System (INIS)

    Complete text of publication follows. Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad central peak (CP) (1), and some additional broad Brillouin doublet (BD) (2), that can both relate to phonon-density fluctuations (3). Starting from extensive new high resolution neutron scattering measurements in pure crystals, low lying phonon sheets were modelled in the central part of Brillouin zone. Such a parameterisation was then used in order to analyse those up-mentioned unusual features in teens of two-phonon mechanisms (4). Numerical evaluations show that transverse acoustic (TA) phonons whose normal damping is faster than the BD frequency (ΓDB > ωDB) may produce hydrodynamic second sound (propagation of heat). Moreover, two-phonon difference scattering from low damping thermal TA phonons ((ΓDB DB) can contribute to the spectra with either a sharp or a broader BD, depending on the phonon group velocity and phonon-sheet anisotropy. The position of the doublet is consistent with both mechanisms, but comparing the computed anisotropies with experimental Brillouin and neutron scattering data, one favours the second process. (author)

  20. Nonlinear Evolutions of Stimulated Raman and Brillouin Scattering Processes in Partially Stripped-Ion Plasmas

    Institute of Scientific and Technical Information of China (English)

    胡业民; 胡希伟

    2001-01-01

    Numerical analyses for the nonlinear evolutions of stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) processes are given. Various effects of the second- and third-order nonlinear susceptibilities on the SRS and SBS processes are studied. The nonlinear evolutions of SRS and SBS processes are atfected more efficiently than their linear growth rates by the nonlinear susceptibility.

  1. Performance Analysis of Temperature and Strain Simultaneous Measurement System Based on Heterodyne Detection of Brillouin Scattering

    Institute of Scientific and Technical Information of China (English)

    Ji-Sheng Zhang; Yong-Qian Li; Shuo Zhang; Li-Juan Zhao

    2008-01-01

    Microwave heterodyne detection can be used to measure the temperature and strain distribution along a fiber with high accuracy in a Brillouin optical time domain reflectometry (BOTDR) system. This method involves simultaneous measurement of Brillouin scattering and Rayleigh scattering in fiber, and scanning of Briliouin spectrum to obtain the desired information. This paper presents a simultaneous measurement system of temperature and strain based on microwave detection and analyzed the system performances such as measurement accuracy, dynamic range, and spatial resolution theoretically. The analysis shows that the system can achieve a temperature resolution of 1℃ and a strain resolution of 100 με.

  2. Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

    DEFF Research Database (Denmark)

    Klieber, Christoph; Hecksher, Tina; Pezeril, Thomas;

    2013-01-01

    of the frequency dependence of the speed of sound and the sound-wave attenuation. When the data are converted into mechanical moduli, a linear relationship between longitudinal and shear acoustic moduli is revealed, which is consistent with the generalized Cauchy relation. In glycerol, the temperature dependence......This paper presents and discusses the temperature and frequency dependence of the longitudinal and shear viscoelastic response at MHz and GHz frequencies of the intermediate glass former glycerol and the fragile glass former tetramethyl-tetraphenyl-trisiloxane (DC704). Measurements were performed...... of the shear acoustic relaxation time agrees well with literature data for dielectric measurements. In DC704, combining the new data with data from measurements obtained previously by piezo-ceramic transducers yields figures showing the longitudinal and shear sound velocities at frequencies from mHz to GHz...

  3. Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

    DEFF Research Database (Denmark)

    Klieber, Christoph; Hecksher, Tina; Pezeril, Thomas;

    2013-01-01

    of the shear acoustic relaxation time agrees well with literature data for dielectric measurements. In DC704, combining the new data with data from measurements obtained previously by piezo-ceramic transducers yields figures showing the longitudinal and shear sound velocities at frequencies from mHz to GHz...

  4. Stimulated Brillouin scatter and stimulated ion Bernstein scatter during electron gyroharmonic heating experiments

    Science.gov (United States)

    Fu, H.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Mahmoudian, A.; Briczinski, S. J.; McCarrick, M. J.

    2013-09-01

    Results of secondary radiation, Stimulated Electromagnetic Emission (SEE), produced during ionospheric modification experiments using ground-based high-power radio waves are reported. These results obtained at the High Frequency Active Auroral Research Program (HAARP) facility specifically considered the generation of Magnetized Stimulated Brillouin Scatter (MSBS) and Stimulated Ion Bernstein Scatter (SIBS) lines in the SEE spectrum when the transmitter frequency is near harmonics of the electron gyrofrequency. The heater antenna beam angle effect was investigated on MSBS in detail and shows a new spectral line postulated to be generated near the upper hybrid resonance region due to ion acoustic wave interaction. Frequency sweeping experiments near the electron gyroharmonics show for the first time the transition from MSBS to SIBS lines as the heater pump frequency approaches the gyroharmonic. Significantly far from the gyroharmonic, MSBS lines dominate, while close to the gyroharmonic, SIBS lines strengthen while MSBS lines weaken. New possibilities for diagnostic information are discussed in light of these new observations.

  5. Guided-wave Brillouin scattering in air

    CERN Document Server

    Renninger, William H; Rakich, Peter T

    2016-01-01

    Here we identify a new form of optomechanical coupling in gas-filled hollow-core fibers. Stimulated forward Brillouin scattering is observed in air in the core of a photonic bandgap fiber. A single resonance is observed at 35 MHz, which corresponds to the first excited axial-radial acoustic mode in the air-filled core. The linewidth and coupling strengths are determined by the acoustic loss and electrostrictive coupling in air, respectively. A simple analytical model, refined by numerical simulations, is developed that accurately predicts the Brillouin coupling strength and frequency from the gas and fiber parameters. Since this form of Brillouin coupling depends strongly on both the acoustic and dispersive optical properties of the gas within the fiber, this new type of optomechanical interaction is highly tailorable. These results allow for forward Brillouin spectroscopy in dilute gases, could be useful for sensing and will present a power and noise limitation for certain applications.

  6. Guided acoustic and optical waves in silicon-on-insulator for Brillouin scattering and optomechanics

    CERN Document Server

    Sarabalis, Christopher J; Safavi-Naeini, Amir H

    2016-01-01

    We numerically study silicon waveguides on silica showing that it is possible to simultaneously guide optical and acoustic waves in the technologically important silicon on insulator (SOI) material system. Thin waveguides, or fins, exhibit geometrically softened mechanical modes at gigahertz frequencies with phase velocities below the Rayleigh velocity in glass, eliminating acoustic radiation losses. We propose slot waveguides on glass with telecom optical frequencies and strong radiation pressure forces resulting in Brillouin gains on the order of 500 and 50,000 1/(Wm) for backward and forward Brillouin scattering, respectively.

  7. Guided acoustic and optical waves in silicon-on-insulator for Brillouin scattering and optomechanics

    Science.gov (United States)

    Sarabalis, Christopher J.; Hill, Jeff T.; Safavi-Naeini, Amir H.

    2016-10-01

    We numerically study silicon waveguides on silica showing that it is possible to simultaneously guide optical and acoustic waves in the technologically important silicon on insulator (SOI) material system. Thin waveguides, or fins, exhibit geometrically softened mechanical modes at gigahertz frequencies with phase velocities below the Rayleigh velocity in glass, eliminating acoustic radiation losses. We propose slot waveguides on glass with telecom optical frequencies and strong radiation pressure forces resulting in Brillouin gains on the order of 500 and 50 000 W-1m-1 for backward and forward Brillouin scattering, respectively.

  8. Simulation of Stimulated Brillouin Scattering and Stimulated Raman Scattering In Shock Ignition

    CERN Document Server

    Hao, L; Liu, W D; Yan, R; Ren, C

    2016-01-01

    We study stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) in shock ignition by comparing fluid and PIC simulations. Under typical parameters for the OMEGA experiments [Theobald \\emph{et al}., Phys. Plasmas \\textbf{19}, 102706 (2012)], a series of 1D fluid simulations with laser intensities ranging between 2$\\times$10$^{15}$ and 2$\\times$10$^{16}$ W/cm$^2$ finds that SBS is the dominant instability, which increases significantly with the incident intensity. Strong pump depletion caused by SBS and SRS limits the transmitted intensity at the 0.17n$_c$ to be less than 3.5$\\times$10$^{15}$ W/cm$^2$. The PIC simulations show similar physics but with higher saturation levels for SBS and SRS convective modes and stronger pump depletion due to higher seed levels for the electromagnetic fields in PIC codes. Plasma flow profiles are found to be important in proper modeling of SBS and limiting its reflectivity in both the fluid and PIC simulations.

  9. Physical characterization of magmatic liquids. [Ultrasonic and Brillouin Scattering Studies of Natural and Synthetic Silicates and Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Manghnani, M.H.

    1992-06-05

    This report describes a research project that was conducted from August 15, 1985 to February 28, 1992. The project was based on the ultrasonic studies of natural and synthetic silicate melts, and the study of Brillouin scattering of synthetic silicates and oxides. Measurements of the compressional wave velocity and attenuation can be established using the ultrasonic methods. Temperature dependences of silicates can be established by the Brillouin scattering. (MB)

  10. Neutron Brillouin scattering in dense fluids

    Energy Technology Data Exchange (ETDEWEB)

    Verkerk, P. [Technische Univ. Delft (Netherlands); FINGO Collaboration

    1997-04-01

    Thermal neutron scattering is a typical microscopic probe for investigating dynamics and structure in condensed matter. In contrast, light (Brillouin) scattering with its three orders of magnitude larger wavelength is a typical macroscopic probe. In a series of experiments using the improved small-angle facility of IN5 a significant step forward is made towards reducing the gap between the two. For the first time the transition from the conventional single line in the neutron spectrum scattered by a fluid to the Rayleigh-Brillouin triplet known from light-scattering experiments is clearly and unambiguously observed in the raw neutron data without applying any corrections. Results of these experiments are presented. (author).

  11. Rayleigh-Brillouin Scattering in Binary Gas Mixtures

    CERN Document Server

    Gu, Ziyu; van de Water, Willem; Marques, Wilson

    2015-01-01

    Precise measurements are performed on spectral lineshapes of spontaneous Rayleigh-Brillouin scattering in mixtures of the noble gases Ar and Kr, with He. Admixture of a light He atomic fraction results in marked changes of the spectra, although in all experiments He is merely a spectator atom: it affects the relaxation of density fluctuations of the heavy constituent, but its contribution to the scattered light intensity is negligibly small. The results are compared to a theory for the spectral lineshape without adjustable parameters, yielding excellent agreement for the case of binary mono-atomic gases, signifying a step towards modeling and understanding of light scattering in more complex molecular media.

  12. The Measurement of Tropospheric Temperature Profiles using Rayleigh-Brillouin Scattering: Results from Laboratory and Atmospheric Studies

    Science.gov (United States)

    Witschas, Benjamin; Reitebuch, Oliver; Lemmerz, Christian; Gomez Kableka, Pau; Kondratyev, Sergey; Gu, Ziyu; Ubachs, Wim

    2016-06-01

    In this letter, we suggest a new method for measuring tropospheric temperature profiles using Rayleigh-Brillouin (RB) scattering. We report on laboratory RB scattering measurements in air, demonstrating that temperature can be retrieved from RB spectra with an absolute accuracy of better than 2 K. In addition, we show temperature profiles from 2 km to 15.3 km derived from RB spectra, measured with a high spectral resolution lidar during daytime. A comparison with radiosonde temperature measurements shows reasonable agreement. In cloud-free conditions, the temperature difference reaches up to 5 K within the boundary layer, and is smaller than 2.5 K above. The statistical error of the derived temperatures is between 0.15 K and 1.5 K.

  13. Tunable and reconfigurable single passband filter using stimulated Brillouin scattering and intensity modulation

    Science.gov (United States)

    Hu, Shuling; Xiao, Zeyu; Wang, Huanhuan

    2015-07-01

    A tunable and reconfigurable single passband microwave photonic filter based on stimulated Brillouin scattering (SBS) and intensity modulation is presented and theoretically analyzed. Three Brillouin pumps with equal intensity are generated by selecting appropriate bias voltages and modulation indices. Then a reconfigurable passband can be achieved by superposition of the three pumps. Simulation results demonstrate that the proposed filter has a 22-GHz continuous tuning range with a high out-of-band rejection ratio above 40 dB. The -3-dB bandwidth can be tuned from 12 to 95 MHz, and the flatness is less than 1.5 dB. This technique uses a low-frequency (0 to 35 MHz) modulation signal to realize passband reshaping, and has potential applications in communication and radar systems.

  14. Brillouin-scattering determination of the acoustic properties and their pressure dependence for three polymeric elastomers

    Science.gov (United States)

    Stevens, Lewis L.; Orler, E. Bruce; Dattelbaum, Dana M.; Ahart, Muhtar; Hemley, Russell J.

    2007-09-01

    The acoustic properties of three polymer elastomers, a cross-linked poly(dimethylsiloxane) (Sylgard® 184), a cross-linked terpolymer poly(ethylene-vinyl acetate-vinyl alcohol), and a segmented thermoplastic poly(ester urethane) copolymer (Estane® 5703), have been measured from ambient pressure to approximately 12GPa by using Brillouin scattering in high-pressure diamond anvil cells. The Brillouin-scattering technique is a powerful tool for aiding in the determination of equations of state for a variety of materials, but to date has not been applied to polymers at pressures exceeding a few kilobars. For the three elastomers, both transverse and longitudinal acoustic modes were observed, though the transverse modes were observed only at elevated pressures (>0.7GPa) in all cases. From the Brillouin frequency shifts, longitudinal and transverse sound speeds were calculated, as were the C11 and C12 elastic constants, bulk, shear, and Young's moduli, and Poisson's ratios, and their respective pressure dependencies. P-V isotherms were then constructed, and fit to several empirical/semiempirical equations of state to extract the isothermal bulk modulus and its pressure derivative for each material. Finally, the lack of shear waves observed for any polymer at ambient pressure, and the pressure dependency of their appearance is discussed with regard to instrumental and material considerations.

  15. High speed data encryption and decryption using stimulated Brillouin scattering effect in optical fiber

    Science.gov (United States)

    Yi, Lilin; Zhang, Tao; Hu, Weisheng

    2011-11-01

    A novel all-optical encryption/decryption method based on stimulated Brillouin scattering (SBS) effect in optical fiber is proposed for the first time. The operation principle is explained in detail and the encryption and decryption performance is experimentally evaluated. The encryption keys could be the SBS gain amplitude, bandwidth, central wavelength and spectral shape, which are configurable and flexibly controlled by the users. We experimentally demonstrate the SBS encryption/decryption process of a 10.86-Gb/s non-return-to-zero (NRZ) data by using both phase-modulated and current-dithered Brillouin pumps for proof-of-concept. Unlike the traditional optical encryption methods of chaotic communications and optical code-division-multiplexing access (OCDMA), the SBS based encryption/decryption technique can directly upgrade the current optical communication system to a secure communication system without changing the terminal transceivers, which is completely compatible with the current optical communication systems.

  16. Unified approach to cascaded stimulated Brillouin scattering and frequency-comb generation

    Science.gov (United States)

    Dong, Mark; Winful, Herbert G.

    2016-04-01

    We present a unified approach to cascaded stimulated Brillouin scattering and frequency-comb generation in which the multitude of interacting pump, Stokes, and anti-Stokes optical fields is described by a single forward wave and a single backward wave at a single carrier frequency. The envelopes of these two waves are modulated through coupling to a single acoustic oscillation and through four-wave mixing. Starting from a single pump field, we observe the emergence of a comb of frequencies as the intensity is increased. The set of three differential equations derived here is sufficient to describe the generation of any number of Brillouin sidebands in oscillator systems that would have required hundreds of coupled equations in the standard approach. We test this approach on some published experiments and find excellent agreement with the results.

  17. Simulations of Brillouin Scattering in Optical Fibers

    Science.gov (United States)

    Mungan, Carl; Petersen, Eliot; Huang, Shuochen; White, Jeffrey

    2013-03-01

    Brillouin scattering arises when a laser beam generates density variations in a medium via electrostriction. The density variations modulate the refractive index, resulting in a grating that Bragg scatters pump light into a Stokes beam. The Stokes wave is downshifted in frequency by the Doppler effect because the grating is moving at the speed of acoustic phonons. To conserve both energy and momentum, the Brillouin photons are backscattered. This back-reflected radiation is a major factor limiting the transmission of laser power in optical fibers for practical applications. It is mathematically described by a set of coupled partial differential equations. I will describe some of the known analytic solutions of these equations, as well as how to find numeric solutions using MATLAB. JTO grant 11-SA-0405

  18. Evidence of plasma fluctuations and their effect on the growth of stimulated Brillouin and stimulated Raman scattering in laser plasmas

    International Nuclear Information System (INIS)

    The reflectivity levels of stimulated Brillouin scattering (SBS) in recent large scale length laser plasma experiments is much lower than expected for conditions where the convective gain exponent is expected to be large. Long wavelength velocity fluctuations caused during the plasma formation process, or by parametric instabilities themselves, have been proposed as a mechanism to detune SBS in these experiments and reduce its gain. Evidence of large velocity fluctuation levels is found in the time-resolved SBS spectra from these experiments, and correlates with observed changes in the reflectivity of both SBS and stimulated Raman scattering (SRS). The authors present evidence of fluctuations which increase as the plasma density systematically increases, and discuss their effect on the growth of parametric instabilities

  19. Mechanical properties of low- and high-k dielectric thin films: A surface Brillouin light scattering study

    Science.gov (United States)

    Zizka, J.; King, S.; Every, A. G.; Sooryakumar, R.

    2016-04-01

    Surface Brillouin light scattering measurements are used to determine the elastic constants of nano-porous low-k SiOC:H (165 nm) and high-k HfO2 (25 nm) as well as BN:H (100 nm) films grown on Si substrates. In addition, the study investigates the mechanical properties of ultra-thin (25 nm) blanket TiN cap layers often used as hard masks for patterning, and their effects on the underlying low-k dielectrics that support a high level of interconnected porosity. Depending on the relative material properties of individual component layers, the acoustic modes manifest as confined, propagating, or damped resonances in the light scattering spectra, thereby enabling the mechanical properties of the ultra-thin films to be determined.

  20. Tailorable Stimulated Brillouin Scattering in Nanoscale Silicon Waveguides

    CERN Document Server

    Shin, Heedeuk; Jarecki, Robert; Cox, Jonathan A; Olsson, Roy H; Starbuck, Andrew; Wang, Zheng; Rakich, Peter T

    2013-01-01

    While nanoscale modal confinement radically enhances a variety of nonlinear light-matter interactions within silicon waveguides, traveling-wave stimulated Brillouin scattering nonlinearities have never been observed in silicon nanophotonics. Through a new class of hybrid photonic-phononic waveguides, we demonstrate tailorable traveling-wave forward stimulated Brillouin scattering in nanophotonic silicon waveguides for the first time, yielding 3000 times stronger forward SBS responses than any previous waveguide system. Simulations reveal that a coherent combination of electrostrictive forces and radiation pressures are responsible for greatly enhanced photon-phonon coupling at nano-scales. Highly tailorable Brillouin nonlinearities are produced by engineering the structure of a membrane-suspended waveguide to yield Brillouin resonances from 1 to 18 GHz through high quality-factor (>1000) phonon modes. Such wideband and tailorable stimulated Brillouin scattering in silicon photonics could enable practical real...

  1. Bandwidth reconfigurable microwave photonic filter based on stimulated Brillouin scattering

    Science.gov (United States)

    Xiao, Yongchuan; Wang, Xin; Zhang, Youdi; Dong, Wei; Zhang, Xindong; Liu, Caixia; Ruan, Shengping; Chen, Weiyou

    2015-01-01

    A bandwidth reconfigurable microwave photonic filter is proposed and numerically analyzed employing Brillouin gain spectrum narrowing and broadening. The stimulated Brillouin scattering (SBS) process is used to convert the phase modulation to intensity modulation to generate filter passband. Due to the fact that the passband is formed by mapping the Brillouin gain spectrum, bandwidth reconfiguration can be implemented by changing Brillouin gain linewidth. In this paper, both bandwidth reduction and increase are included in a single system and the details of gain spectrum narrowing and broadening are demonstrated. Theoretically, nearly 60% bandwidth reduction and hundreds times of bandwidth increase are achieved as compared to the case without gain spectrum process.

  2. Short-Pulse Amplification by Strongly-Coupled Brillouin Scattering

    CERN Document Server

    Edwards, Matthew R; Mikhailova, Julia M; Fisch, Nathaniel J

    2016-01-01

    We examine the feasibility of strongly-coupled stimulated Brillouin scattering as a mechanism for the plasma-based amplification of sub-picosecond pulses. In particular, we use fluid theory and particle-in-cell simulations to compare the relative advantages of Raman and Brillouin amplification over a broad range of achievable parameters.

  3. Rayleigh-Brillouin scattering of carbon dioxide

    CERN Document Server

    Gu, Ziyu; van de Water, Willem

    2014-01-01

    The spectral lineshape of spontaneous Rayleigh-Brillouin scattering in CO2 is studied in a range of pressures. The spectrum is influenced by the bulk viscosity, which is a relaxation phenomenon involving the internal degrees of freedom of the molecule. The associated relaxation rates can be compared to the frequency shift of the scattered light, which demands precise measurements of the spectral lineshape. We find the value of the bulk viscosity around 5.7 X 10^{-6} kg/(ms) for the range of pressures p= 2-4 bar and for conditions of room temperature.

  4. Dimensionality reduction and dynamical filtering: Stimulated Brillouin scattering in optical fibers.

    Science.gov (United States)

    Setra, Rafael G; Arroyo-Almanza, Diana A; Ni, Zetian; Murphy, Thomas E; Roy, Rajarshi

    2015-08-01

    Stimulated Brillouin scattering (SBS) is a noise-driven nonlinear interaction between acoustical and optical waves. In optical fibers, SBS can be observed at relatively low optical powers and can severely limit signal transmission. Although SBS is initiated by high dimensional noise, it also exhibits many of the hallmarks of a complex nonlinear dynamical system. We report here a comprehensive experimental and numerical study of the fluctuations in the reflected Stokes wave produced by SBS in optical fibers. Using time series analysis, we demonstrate a reduction of dimensionality and dynamical filtering of the Stokes wave. We begin with a careful comparison of the measured average transmitted and reflected intensities from below the SBS threshold to saturation of the transmitted power. Initially the power spectra and correlation functions of the time series of the reflected wave fluctuations at the SBS threshold and above are measured and simulated. Much greater dynamical insight is provided when we study the scaling behavior of the intensity fluctuations using Hurst exponents and detrended fluctuation analysis for time scales extending over six orders of magnitude. At the highest input powers, we notice the emergence of three distinct dynamical scaling regimes: persistent, Brownian, and antipersistent. Next, we explore the Hilbert phase fluctuations of the intensity time series and amplitude-phase coupling. Finally, time-delay embedding techniques reveal a gradual reduction in dimensionality of the spatiotemporal dynamics as the laser input is increased toward saturation of the transmitted power. Through all of these techniques, we find a transition from noisier to smoother dynamics with increasing input power. We find excellent agreement between our experimental measurements and simulations. PMID:26382472

  5. Cascaded forward Brillouin scattering to all Stokes orders

    CERN Document Server

    Wolff, Christian; Eggleton, Benjamin J; Steel, Michael J; Poulton, Christopher G

    2016-01-01

    Inelastic scattering processes such as Brillouin scattering can often function in cascaded regimes and this is likely to occur in certain integrated opto-acoustic devices. We develop a Hamiltonian formalism for cascaded Brillouin scattering valid for both quantum and classical regimes. By regarding Brillouin scattering as the interaction of a single acoustic envelope and a single optical envelope that covers all Stokes and anti-Stokes orders, we obtain a compact model that is well suited for numerical implementation, extension to include other optical nonlinearities or short pulses, and application in the quantum-optics domain. We then theoretically analyze intra-mode forward Brillouin scattering (FBS) for arbitrary waveguides with and without optical dispersion. In the absence of optical dispersion, we find an exact analytical solution. With a perturbative approach, we furthermore solve the case of weak optical dispersion. Our work leads to several key results on intra-mode FBS. For negligible dispersion, we...

  6. Stimulated Brillouin scattering in metamaterials

    Science.gov (United States)

    Smith, M. J. A.; Wolff, C.; Martijn de Sterke, C.; Lapine, M.; Kuhlmey, B. T.; Poulton, C. G.

    2016-10-01

    We compute the SBS gain for a metamaterial comprising a cubic lattice of dielectric spheres suspended in a background dielectric material. Theoretical methods are presented to calculate the optical, acoustic, and opto-acoustic parameters that describe the SBS properties of the material at long wavelengths. Using the electromagnetic and strain energy densities we accurately characterise the optical and acoustic properties of the metamaterial. From a combination of energy density methods and perturbation theory, we recover the appropriate terms of the photoelastic tensor for the metamaterial. We demonstrate that electrostriction is not necessarily the dominant mechanism in the enhancement and suppression of the SBS gain coefficient in a metamaterial, and that other parameters, such as the Brillouin linewidth, can dominate instead. Examples are presented that exhibit an order of magnitude enhancement in the SBS gain as well as perfect suppression.

  7. Stimulated Brillouin scattering in metamaterials

    CERN Document Server

    Smith, M J A; de Sterke, C Martijn; Wolff, C; Lapine, M; Poulton, C G

    2016-01-01

    We compute the SBS gain for a metamaterial comprising a cubic lattice of dielectric spheres suspended in a background dielectric material. Theoretical methods are presented to calculate the optical, acoustic, and opto-acoustic parameters that describe the SBS properties of the material at long wavelengths. Using the electromagnetic and strain energy densities we accurately characterise the optical and acoustic properties of the metamaterial. From a combination of energy density methods and perturbation theory, we recover the appropriate terms of the photoelastic tensor for the metamaterial. We demonstrate that electrostriction is not necessarily the dominant mechanism in the enhancement and suppression of the SBS gain coefficient in a metamaterial, and that other parameters, such as the Brillouin linewidth, can dominate instead. Examples are presented that exhibit an order of magnitude enhancement in the SBS gain as well as perfect suppression.

  8. Forward and backward intensity noises induced by stimulated Brillouin scattering in optical fiber

    Institute of Scientific and Technical Information of China (English)

    Wei Chen; Zhou Meng

    2012-01-01

    The characteristic of intensity noise is degraded when stimulated Brillouin scattering (SBS) occurs in the fiber transmission systems. We use the localized fluctuating model to study SBS and obtain the curves of intensity fluctuations versus the single-pass gain. Corresponding experiments are also conducted. For the forward light, the relative intensity noise (RIN) dramatically increases at first and gradually stabilizes when the input power S above the SBS threshold. For the backward light, the RIN increases dramatically with the input power near the threshold. As the input power continues to increase, the RIN decreases quickly at first and subsequently decreases slowly. This observation is attributed to the lower frequencies.%The characteristic of intensity noise is degraded when stimulated Brillouin scattering (SBS) occurs in the fiber transmission systems.We use the localized fluctuating model to study SBS and obtain the curves of intensity fluctuations versus the single-pass gain.Corresponding experiments are also conducted.For the forward light,the relative intensity noise (RIN) dramatically increases at first and gradually stabilizes when the input power is above the SBS threshold.For the backward light,the RIN increases dramatically with the input power near the threshold.As the input power continues to increase,the RIN decreases quickly at first and subsequently decreases slowly.This observation is attributed to the lower frequencies.

  9. Rayleigh-Brillouin scattering profiles of air at different temperatures and pressures

    CERN Document Server

    Gu, Ziyu; van de Water, Willem; Ubachs, Wim

    2013-01-01

    Rayleigh Brillouin (RB) scattering profiles for air have been recorded for the temperature range from 255 to 340 K and the pressure range from 640 to 3300 mbar, covering the conditions relevant for the Earth's atmosphere and for planned atmospheric light detection and ranging (LIDAR) missions. The measurements performed at a wavelength of 366.8 nm detect spontaneous RB scattering at a 90 degree scattering angle from a sensitive intracavity setup, delivering scattering profiles at a 1 percent rms noise level or better. The elusive transport coefficient, the bulk viscosity, is effectively derived by a comparing the measurements to the model, yielding an increased trend. The calculated (Tenti S6) line shapes are consistent with experimental data at the level of 2 percent, meeting the requirements for the future RB scattering LIDAR missions in the Earth's atmosphere. However, the systematic 2 percent deviation may imply that the model has a limit to describe the finest details of RB scattering in air. Finally, it...

  10. Spectroscopic properties of KGd(WO 4) 2 and KGd(WO 4) 2:Ho 3+ single crystals studied by Brillouin and Raman scattering methods

    Science.gov (United States)

    Kasprowicz, D.; Runka, T.; Szybowicz, M.; Drozdowski, M.; Majchrowski, A.; Michalski, E.; Żmija, J.

    2006-07-01

    KGd(WO 4) 2 single crystals, pure and doped with holmium ions Ho 3+ at 0.5 and 1% concentrations were investigated by Brillouin and Raman scattering methods. Polarized Raman spectra of KGd(WO 4) 2 and KGd(WO 4) 2:Ho 3+ single crystals have been measured at room temperature. The assignment of the Raman-active A g and B g modes have been performed. Brillouin spectra were collected for the acoustic phonons propagating in [100], [001], [101], [-101], [110], [-110], [011] and [0-11] directions in KGd(WO 4) 2 and KGd(WO 4) 2:Ho 3+ single crystals at room temperature. Obtained results have been discussed in terms of the influence of the doping concentration on the lattice dynamics and crystal structure.

  11. Stimulated Brillouin scattering mirror system, high power laser and laser peening method and system using same

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-04-24

    A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

  12. Stimulated Brillouin scattering gain bandwidth reduction and applications in microwave photonics and optical signal processing

    Science.gov (United States)

    Preussler, Stefan; Schneider, Thomas

    2016-03-01

    Stimulated Brillouin scattering (SBS) is one of the most dominant nonlinear effects in standard single-mode fibers and its unique spectral characteristics, especially the narrow bandwidth, enable many different applications. Most of the applications would benefit from a narrower bandwidth. Different methods for the bandwidth reduction of SBS in optical fibers are presented and discussed. A bandwidth reduction down to 17% of the natural gain can be achieved by the superposition of the gain with two losses or the utilization of a multistage system. Furthermore, applications in the field of microwave photonics and optical signal processing like high-resolution spectroscopy of communication signals, the storage of optical data packets as well as the processing of frequency combs including generation of millimeter waves and ideal sinc-shaped Nyquist pulses are presented.

  13. Dispersion and damping of multi-quantum well polaritons from resonant Brillouin scattering by folded acoustic modes

    OpenAIRE

    Jusserand, B.; Fainstein, A.; Ferreira, R.; Majrab, S.; Lemaitre, A.

    2011-01-01

    We report on confined exciton resonances of acoustic and folded acoustic phonon light scattering in a GaAs/AlAs multi-quantum-well. Significant variations of the line shifts and widths are observed across the resonance and quantitatively reproduced in terms of the polariton dispersion. This high resolution Brillouin study brings new unexpectedly detailed informations on the polariton dynamics in confined systems.

  14. Modeling of the Competition of Stimulated Raman and Brillouin Scattering in LULI Multiple Beam Experiments

    Science.gov (United States)

    Cohen, B. I.; Baldis, H. A.; Berger, R. L.; Williams, E. A.; Labaune, C.

    1999-11-01

    Multiple laser beam experiments with CH target foils at the LULI facility demonstrate anti-correlation of stimulated Brillouin and Raman backscatter (SBS and SRS).(C. Labaune, et al.), Phys. Plasmas 6, 2048 (1999). Detailed Thomson scattering diagnostics show that SBS precedes SRS, that secondary electron plasma waves can accompany SRS appropriate to the Langmuir Decay Instability (LDI), and that with multiple interaction beams the SBS signal in the primary laser beam is reduced while the SRS signal is enhanced and onsets earlier. Analysis and numerical calculations are presented that evaluate the influence of mode coupling (B. Cohen, et al.), Phys. Plasmas 5, 3402 (1998). of SBS and LDI ion waves and local pump depletion in laser hot spots. The modeling suggests that ponderomotive and thermal self-focusing should modify the probability distribution of intense speckles and enhance the local pump depletion and ion wave mode coupling.

  15. Brillouin light scattering study of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al and Co$_{2}$FeAl Heusler compounds

    OpenAIRE

    Gaier, O.; Hamrle, J.; Trudel, S; Parra, A. Conca; Hillebrands, B.; Arbelo, E.; Herbort, C.; Jourdan, M

    2008-01-01

    The thermal magnonic spectra of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al (CCFA) and Co$_2$FeAl were investigated using Brillouin light scattering spectroscopy (BLS). For CCFA, the exchange constant A (exchange stiffness D) is found to be 0.48 $\\mu$erg/cm (203 meV A$^2$), while for Co$_2$FeAl the corresponding values of 1.55 $\\mu$erg/cm (370 meV A$^2$) were found. The observed asymmetry in the BLS spectra between the Stokes and anti-Stokes frequencies was assigned to an interplay between the asymmetrica...

  16. Precise Determination of Brillouin Scattering Spectrum Using a Virtually Imaged Phase Array (VIPA) Spectrometer and Charge-Coupled Device (CCD) Camera.

    Science.gov (United States)

    Meng, Zhaokai; Yakovlev, Vladislav V

    2016-08-01

    Brillouin spectroscopy is an emerging tool for microscopic optical imaging as it allows noninvasive assessment of viscoelastic properties of materials. The use of atomic-molecular absorption cells as ultra-narrow notch filters allows acquisition of Brillouin spectra from turbid samples despite their strong elastic scattering. However, such systems alter the shapes of the Brillouin lines, making the precise determination of the Brillouin shift difficult. In this report, we propose a simple method for analyzing the Brillouin spectrum using a customized least-square fitting algorithm. The absorption spectrum induced by the atomic-molecular cell was taken into consideration. The capability of the method is confirmed by processing experimental spectroscopic data from the pure water at different temperatures. The accuracy of the measurements of ±1 MHz spectral line shift is experimentally demonstrated. PMID:27296309

  17. Brillouin scattering of light by spin waves in ferromagnetic nanorods

    International Nuclear Information System (INIS)

    We report the investigations of spin wave modes of arrays of Ni and Co nanorods using Brillouin light scattering. We have revealed the significant influence of spin wave modes along the nanorod axis in contrast to infinite magnetic nanowires. Unusual optical properties featuring an inverted Stokes/anti-Stokes asymmetry of the Brillouin scattering spectra have been observed. The spectrum of spin wave modes in the nanorod array has been calculated and compared with the experiment. Experimental observations are explained in terms of a combined numerical–analytical approach taking into account both the low aspect ratio of individual magnetic nanorods and dipolar magnetic coupling between the nanorods in the array. The optical studies of spin-wave modes in nanorod metamaterials with low aspect ratio nanorods have revealed new magnetic and magneto-optical properties compared to continuous magnetic films or infinite magnetic nanowires. Such magnetic artificial materials are important class of active metamaterials needed for prospective data storage and signal processing applications.

  18. Hydrophobic hydration of tert-butyl alcohol studied by Brillouin light and inelastic ultraviolet scattering

    Science.gov (United States)

    Lupi, L.; Comez, L.; Masciovecchio, C.; Morresi, A.; Paolantoni, M.; Sassi, P.; Scarponi, F.; Fioretto, D.

    2011-02-01

    The longitudinal viscosity of diluted water-tert-butyl alcohol solutions in the 10 GHz frequency region has been measured by means of Brillouin light scattering and inelastic ultraviolet scattering. The main advantage of our hypersonic investigation compared to more traditional ultrasonic measurements is that in the gigahertz frequency range slow relaxation processes involving the alcohol dynamics are completely unrelaxed, so that the measured viscosity mainly originates from the hydrogen bond restructuring of water. In contrast with previous determinations, we estimate an activation energy which is independent from the alcohol mole fraction up to X = 0.1, and comparable to that of bulk water. A simple two-component model is used to describe the steep increase of viscosity with increasing alcohol mole fraction, and a retardation factor 1.7 ± 0.2 is found between the relaxation times of hydration and bulk water. These findings endorse a dynamic scenario where the slowing down of hydration water is mainly due to a reduction of configurational entropy and does not involve an arrested, icelike, dynamics.

  19. Stimulated Raman-Brillouin scattering processes in magnetoactive semiconductor plasma

    International Nuclear Information System (INIS)

    A simple analytical treatment based on hydrodynamic model of plasma is developed to study both steady-state and transient stimulated Raman and Brillouin scattering processes (SRS and SBS) in centrosymmetric or weakly non centrosymmetric semiconductors. Gain constants, threshold-pump intensities, and optimum-pulse durations for the onset of Raman and Brillouin instabilities are estimated. Authors have also addressed themselves to the question of behaviour of the transient gain factors (Raman and Brillouin) as function of different physical parameters such as external magnetic field, pump pulse durations etc. The quantitative behaviour of transient gain factors is found to be in agreement with the experimental and other theoretical observations. The analysis explain satisfactorily the competition between stimulated Raman and Brillouin processes in the short and long pulse duration regimes. The highlight of present theory is that both SRS and SBS (steady-state as well as transient) can be studied in centrosymmetric or weakly non centrosymmetric dielectrics using simple classical treatment. (author)

  20. Determination of elastic, piezoelectric, and dielectric constants of an R: BaTiO3 single crystal by Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    He Xiao-Kang; Zeng Li-Bo; Wu Qiong-Shui; Zhang Li-Yan; Zhu Ke; Liu Yu-Long

    2012-01-01

    From the sound velocity measured using the Brillouin scattering technique,the elastic,piezoelectric,and dielectric constants of a high-quality monodomain tetragonal Rh:BaTiO3 single crystal are determined at room temperature.The elastic constants are in fairly good agreement with those of the BaTiO3 single crystal,measured previously by Brillouin scattering and the low-frequency equivalent circuit methods.However,their electromechanical properties are significantly different.Based on the sound propagation equations and these results,the directional dependence of the compressional modulus and the shear modulus of Rh:BaTiO3 in the (010) plane is investigated.Some properties of sound propagation and electromechanical coupling in the crystal are discussed.

  1. Incoherent and coherent beam combination for master oscillator/power amplifier system with stimulated Brillouin scattering mirror

    Institute of Scientific and Technical Information of China (English)

    Fu Shi-You; Tian Zhao-Shuo; Shi Xiao-Li; Sun Zheng-He

    2008-01-01

    In this paper,we studied incoherent and coherent beam combining for the master oscillator/power amplifier (MOPA) system with stimulated Brillouin scattering (SBS) mirror.Optic field intensity distributions in the near and fax field are numerically calculated for the two kinds of system.The results show that good beam quality in the far field could be obtained.It provides a theoretical basis for experimental research in the future.

  2. Modeling of the competition of stimulated Raman and Brillouin scatter in multiple beam experiments

    Science.gov (United States)

    Cohen, Bruce I.; Baldis, Hector A.; Berger, Richard L.; Estabrook, Kent G.; Williams, Edward A.; Labaune, Christine

    2001-02-01

    Multiple laser beam experiments with plastic target foils at the Laboratoire pour L'Utilisation des Lasers Intenses (LULI) facility [Baldis et al., Phys. Rev. Lett. 77, 2957 (1996)] demonstrated anticorrelation of stimulated Brillouin and Raman backscatter (SBS and SRS). Detailed Thomson scattering diagnostics showed that SBS always precedes SRS, that secondary electron plasma waves sometimes accompanied SRS appropriate to the Langmuir Decay Instability (LDI), and that, with multiple interaction laser beams, the SBS direct backscatter signal in the primary laser beam was reduced while the SRS backscatter signal was enhanced and occurred earlier in time. Analysis and numerical calculations are presented here that evaluate the influences on the competition of SBS and SRS, of local pump depletion in laser hot spots due to SBS, of mode coupling of SBS and LDI ion waves, and of optical mixing of secondary and primary laser beams. These influences can be significant. The calculations take into account simple models of the laser beam hot-spot intensity probability distributions and assess whether ponderomotive and thermal self-focusing are significant. Within the limits of the model, which omits several other potentially important nonlinearities, the calculations suggest the effectiveness of local pump depletion, ion wave mode coupling, and optical mixing in affecting the LULI observations.

  3. Coherent forward stimulated Brillouin scattering of a spatially incoherent laser beam in a plasma and its effect on beam spray

    OpenAIRE

    Grech, M.; Riazuelo, G.; Pesme, D.; S. Weber; Tikhonchuk, V. T.

    2008-01-01

    A statistical model for forward stimulated Brillouin scattering (FSBS) is developed for a spatially incoherent, monochromatic, laser beam propagating in a plasma. A threshold for the average power in a speckle is found, well below the self-focusing one, above which the laser beam spatial incoherence can not prevent the coherent growth of FSBS. Three-dimensional simulations confirm its existence and reveal the onset of beam spray above it. From these results, we propose a new figure of merit f...

  4. Disorder-driven nonequilibrium melting studied by electron diffraction, brillouin scattering, and molecular dynamics

    International Nuclear Information System (INIS)

    In the present paper, a brief overview of the electron diffraction, Brillouin scattering and molecular dynamics studies of radiation-induced amorphization of ordered intermetallic compounds is presented. In these studies, measured changes in the velocity of surface acoustic phonons, lattice constant, and the Bragg-Williams long-range order parameter induced by irradiation were compared with the results of computer simulations of defect-induced amorphization. The results indicate that progressive chemical disordering of the superlattice structure during irradiation is accompanied by an expansion of the lattice and a large change in sound velocity corresponding to a ∼ 50% decrease in the average shear modulus. The onset of amorphization occurs when the average shear modulus of the crystalline compound becomes equal to that of the amorphous phase. This elastic softening criterion for the onset of amorphization and the dependence of the average shear modulus on the long-range-order parameter are in excellent agreement with molecular dynamics simulations. Both the experimental observations and computer simulations confirm the predictions of the generalized Lindemann melting criterion which stipulates that thermodynamic melting of a defective crystal occurs when the sum of the dynamic and static mean-square atomic displacements reaches a critical value identical to that for melting of the defect-free crystal. In this broader view of melting, the crystal-to-glass transformation is a disorder-driven nonequilibrium melting process occurring at temperatures below the Kauzmann isentropic glass-transition temperature

  5. Photonic chip based tunable and reconfigurable narrowband microwave photonic filter using stimulated Brillouin scattering.

    Science.gov (United States)

    Byrnes, Adam; Pant, Ravi; Li, Enbang; Choi, Duk-Yong; Poulton, Christopher G; Fan, Shanhui; Madden, Steve; Luther-Davies, Barry; Eggleton, Benjamin J

    2012-08-13

    We report the first demonstration of a photonic chip based dynamically reconfigurable, widely tunable, narrow pass-band, high Q microwave photonic filter (MPF). We exploit stimulated Brillouin scattering (SBS) in a 6.5 cm long chalcogenide (As2S3) photonic chip to demonstrate a MPF that exhibited a high quality factor of ~520 and narrow bandwidth and was dynamically reconfigurable and widely tunable. It maintained a stable 3 dB bandwidth of 23 ± 2MHz and amplitude of 20 ± 2 dB over a large frequency tuning range of 2-12 GHz. By tailoring the pump spectrum, we reconfigured the 3 dB bandwidth of the MPF from ~20 MHz to ~40 MHz and tuned the shape factor from 3.5 to 2 resulting in a nearly flat-topped filter profile. This demonstration represents a significant advance in integrated microwave photonics with potential applications in on-chip microwave signal processing for RADAR and analogue communications. PMID:23038523

  6. Signal Processing for Fibre-optic Distributed Sensing Techniques Employing Brillouin Scattering

    Institute of Scientific and Technical Information of China (English)

    XIAO Shang-hui; LI Li

    2009-01-01

    As fibre optic distributed scattering sensing systems are providing innovative solutions for the monitoring of large structures, Brillouin-based distributed scattering sensing techniques represent a new physical approach for structures health monitoring, which seems extremely promising and is receiving most attentions. This paper comprehensively presents some methods of signal interrogation for fibre optic Brillouin-based distributed scattering sensing technology, especially establishes an accurate Pseudo-Voigt model of Brillouin gain spectrum and gives some results on spectrum analysis and data processing.

  7. Effect of collisions on amplification of laser beams by Brillouin scattering in plasmas

    OpenAIRE

    Humphrey, K. A.; Trines, R. M. G. M.; Fiuza, F.; Speirs, D. C.; Norreys, P.; Cairns, R. A.; Silva, L. O.; R. Bingham

    2013-01-01

    We report on particle in cell simulations of energy transfer between a laser pump beam and a counter-propagating seed beam using the Brillouin scattering process in uniform plasma including collisions. The results presented show that the ion acoustic waves excited through naturally occurring Brillouin scattering of the pump field are preferentially damped without affecting the driven Brillouin scattering process resulting from the beating of the pump and seed fields together. We find that col...

  8. Elasticity of Pyrope at High Pressures and Temperatures by Brillouin Scattering and X-ray Diffraction

    Science.gov (United States)

    Lu, C.; Mao, Z.; Lin, J.; Prakapenka, V.

    2011-12-01

    Iron-containing pyrope ((Fe,Mg)3Al2Si3O12)) is believed to be an abundant rock-forming mineral in the Earth's interior, ranging from the crust to the top of the lower mantle. Based on the pyrolite mineralogical model, pyrope accounts for 13% by volume in the upper mantle and 10% in the transition zone. Therefore, laboratory measurements on the elasticity of pyrope at relevant pressure and temperature conditions are critical in understanding the seismic images and in constraining the chemistry and mineralogy of the region. The elasticity of single-crystal pyrope has been studied up to 20 GPa at 300 K and up to 1100 K at 1 bar, yet it has never been investigated at simultaneous high pressure-temperature conditions. Thus, much of our knowledge of the upper mantle and transition zone seismic profiles largely relies on extrapolated experimental results or theoretical calculations. Here we have measured the single-crystal elasticity of garnet, ((Mg2.04Ca0.16Fe0.74)Al2.02(SiO4)3) up to 20 GPa and 750 K using combined Brillouin scattering and synchrontron X-ray diffraction in an externally-heated diamond anvil cell at GSECARS of the Advanced Photon Source, Argonne National Laboratory. We have derived full elastic constants (Cij) of the sample as a function of pressure and temperature at relevant conditions of the deep mantle. The temperature derivatives of the Cijs are similar to that at ambient pressure, indicating a minimal pressure effect. Together with the elasticity of other major mantle minerals, we have used a thermoelastic model to reconstruct the seismic velocity profile of the upper mantle and the transition zone and to reference the mineralogy of the regions.

  9. Distributed Temperature and Strain Discrimination with Stimulated Brillouin Scattering and Rayleigh Backscatter in an Optical Fiber

    Directory of Open Access Journals (Sweden)

    Xiaoyi Bao

    2013-01-01

    Full Text Available A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA with differential pulse-width pair technique, while the spectrum shift of the Rayleigh backscatter is measured using optical frequency-domain reflectometry (OFDR. These shifts are the functions of both temperature and strain, and can be used as two independent parameters for the discrimination of temperature and strain. A 92 m measurable range with the spatial resolution of 50 cm is demonstrated experimentally, and accuracies of ±1.2 °C in temperature and ±15 με in strain could be achieved.

  10. A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths

    CERN Document Server

    Gu, Ziyu; van Duijn, Eric-Jan; Ubachs, Wim; 10.1063/1.4721272

    2012-01-01

    A spectrometer for the measurement of spontaneous Rayleigh-Brillouin scattering line profiles at ultraviolet wavelengths from gas phase molecules has been developed, employing a high-power frequency-stabilized UV laser with narrow bandwidth (2 MHz). The UV light from a frequency-doubled titanium:sapphire laser is further amplified in an enhancement cavity, delivering a 5 Watt UV-beam propagating through the interaction region inside a scattering cell. The design of the RB-scattering cell allows for measurements at gas pressures in the range 0-4 bar and at stably controlled temperatures from -30 to 70 degree Celsius. A scannable Fabry-Perot analyzer with instrument resolution of 232 MHz probes the Rayleigh-Brillouin profiles. Measurements on N2 and SF6 gases demonstrate the high signal-to-noise ratio achievable with the instrument, at the 1% level at the peak amplitude of the scattering profile.

  11. Nonstationary stimulated Brillouin scattering in laser plasma

    International Nuclear Information System (INIS)

    Stimulated Brillouin scattering (SBS) is a known phenomenon observed in many laser plasma experiments. In spite of enormous amount of experimental and theoretical works there are some properties of SBS that have no ambiguous interpretation yet. Here we try to explain some characteristic features of SBS taking place in the high intensity laser plasma interaction. Here we compare numerical results with experimental data obtained with use of CO2 laser facility TIR-1. Experiments have been performed under the next parameters of the laser system: energy of up to 100 J, pulse length (FWHM) of 3 ns, contrast ratio larger than 107, wavelength of 10.591 mkm. The NaCl aspherical lens was used to focus the laser beam on the plane massive target. Intensity distribution in the focal plate had near Gaussian distribution with diameter (1/e) of 65 mkm, maximum intensity being 5.*1014 W/cm2. One of the most characteristic features of SBS in these experiments is its nonstationarity. (author) 4 refs., 3 figs

  12. An All-Optical Frequency Up/Down-Converter Utilizing Stimulated Brillouin Scattering In A Trf And Dcf For Rof Application

    Directory of Open Access Journals (Sweden)

    N. A. Awang

    2011-09-01

    Full Text Available A frequency up and down conversion is proposed based on stimulated Brillouin scattering (SBS for Radio-over-fiber (RoF system. Microwave frequency up conversion from 2GHz to 12.5GHz and microwave frequency down conversion from 12.5GHz to 1.8GHz with largest Intermediate Frequency (IF power of -32dBm is successfully demonstrated. The up conversion is based on the 1st Stokes of Brillouin fiber laser in Truewave reach fiber (TWF and the down conversion is based on 1st AntiStokes of Brillouin fiber laser in Dispersion compensating fiber (DCF.

  13. An All-Optical Frequency Up/Down-Converter Utilizing Stimulated Brillouin Scattering In A Trf And Dcf For Rof Application

    OpenAIRE

    N. A. Awang; H Ahmad; S. F. Norizan; M.Z. Zulkifli; Z.A. Ghani; S. W. Harun

    2011-01-01

    A frequency up and down conversion is proposed based on stimulated Brillouin scattering (SBS) for Radio-over-fiber (RoF) system. Microwave frequency up conversion from 2GHz to 12.5GHz and microwave frequency down conversion from 12.5GHz to 1.8GHz with largest Intermediate Frequency (IF) power of -32dBm is successfully demonstrated. The up conversion is based on the 1st Stokes of Brillouin fiber laser in Truewave reach fiber (TWF) and the down conversion is based on 1st AntiStokes of Brillouin...

  14. Design and analysis of single-mode tellurite photonic crystal fibers for stimulated Brillouin scattering based slow-light generation.

    Science.gov (United States)

    Jain, Varsha; Sharma, Shubham; Saini, Than Singh; Kumar, Ajeet; Sinha, Ravindra Kumar

    2016-09-01

    We theoretically examine two designs of single-mode (i) Er-doped tellurite and (ii) undoped tellurite photonic crystal fiber (PCF) for generation of slow light with tunable features based on stimulated Brillouin scattering. We obtained (i) Brillouin gain up to 91 dB and time delay of ∼145  ns at maximum allowable pump power of ∼775  mW in a 2 m Er-doped tellurite PCF and (ii) Brillouin gain up to ∼88  dB and time delay of ∼154  ns at maximum allowable pump power ∼21  mW in a 100 m undoped tellurite photonic crystal fiber. Simulated results clearly indicate that the doped tellurite PCF with Er enhances the maximum allowable pump power and comparable time delay can be obtained even with reduced photonic crystal fiber length. We believe that the carried out examination and simulation have potential impact on design and development of slow-light-based photonic devices applicable in telecommunication systems, enhancement of optical forces, and quantum computing. PMID:27607250

  15. Phase-locking in cascaded stimulated Brillouin scattering

    CERN Document Server

    Büttner, Thomas F S; Steel, M J; Hudson, Darren D; Eggleton, Benjamin J

    2015-01-01

    Cascaded stimulated Brillouin scattering (SBS) is a complex nonlinear optical process that results in the generation of several optical waves that are frequency shifted by an acoustic resonance frequency. Four-wave mixing (FWM) between these Brillouin shifted optical waves can create an equally spaced optical frequency comb with a stable spectral phase, i.e. a Brillouin frequency comb (BFC). Here, we investigate phase-locking of the spectral components of BFCs, considering FWM interactions arising from the Kerr-nonlinearity as well as from coupling by the acoustic field. Deriving for the first time the coupled-mode equations that include all relevant nonlinear interactions, we examine the contribution of the various nonlinear processes to phase-locking, and show that different regimes can be obtained that depend on the length scale on which the field amplitudes vary.

  16. Phase-locking in cascaded stimulated Brillouin scattering

    Science.gov (United States)

    Büttner, Thomas F. S.; Poulton, Christopher G.; Steel, M. J.; Hudson, Darren D.; Eggleton, Benjamin J.

    2016-02-01

    Cascaded stimulated Brillouin scattering is a complex nonlinear optical process that results in the generation of several optical waves that are frequency shifted by an acoustic resonance frequency. Four-wave mixing (FWM) between these Brillouin shifted optical waves can create an equally spaced optical frequency comb with a stable spectral phase, i.e. a Brillouin frequency comb (BFC). Here, we investigate phase-locking of the spectral components of BFCs, considering FWM interactions arising from the Kerr-nonlinearity as well as from coupling by the acoustic field. Deriving for the first time the coupled-mode equations that include all relevant nonlinear interactions, we examine the contribution of the various nonlinear processes to phase-locking, and show that different regimes can be obtained that depend on the length scale on which the field amplitudes vary.

  17. Brillouin light scattering study of Co2Cr0.6Fe0.4Al and Co2FeAl Heusler compounds

    International Nuclear Information System (INIS)

    The thermal magnonic spectra of Co2Cr0.6Fe0.4Al (CCFA) and Co2FeAl were investigated using Brillouin light scattering (BLS) spectroscopy. For CCFA, the exchange constant A (exchange stiffness D) is found to be 0.48 ± 0.04 μerg cm-1 (203 ± 16 meV A2), while for Co2FeAl the corresponding values of 1.55 ± 0.05 μerg cm-1 (370 ± 10 meV A2) were found. The observed asymmetry in the BLS spectra between the Stokes and anti-Stokes frequencies was assigned to an interplay between the asymmetrical profiles of hybridized Damon-Esbach and perpendicular standing spin-wave modes, combined with the optical sensitivity of the BLS signal to the upper side of the CCFA or Co2FeAl film.

  18. Dynamic stimulated Brillouin scattering analysis

    DEFF Research Database (Denmark)

    Djupsöbacka, A.; Jacobsen, Gunnar; Tromborg, Bjarne

    2000-01-01

    We present a new simple analysis - including the effect of spontaneous emission - of the (dynamic) influence of SBS on the detected receiver eye diagram. It applies in principle for general types of modulation formats such as the digital formats of ASK, FSK, and PSK. The analysis is formulated fo...

  19. Noise and dynamics in forward Brillouin interactions

    CERN Document Server

    Kharel, Prashanta; Renninger, William; Rakich, Peter

    2015-01-01

    In this paper, we explore the spatio-temporal dynamics of spontaneous and stimulated forward Brillouin scattering. This general treatment incorporates the optomechanical coupling produced by boundary-induced radiation pressures (boundary motion) and material-induced electrostrictive forces (photo-elastic effects), permitting straightforward application to a range of emerging micro- and nano-scale optomechanical systems. Through a self-consistent fully coupled nonlinear treatment, developed within a general Hamiltonian framework, we establish the connection between the power spectral density of spontaneously scattered light in forward Brillouin interactions and the nonlinear coupling strength. We show that, in sharp contrast to backward Brillouin scattering, noise-initiated stimulated forward Brillouin scattering is forbidden in the majority of experimental systems. In fact, the single-pass gain, which characterizes the threshold for energy transfer in back-scattering processes, is negative for a large class o...

  20. Extreme temperature sensing using brillouin scattering in optical fibers

    CERN Document Server

    Fellay, Alexandre

    Stimulated Brillouin scattering in silica-based optical fibers may be considered from two different and complementary standpoints. For a physicist, this interaction of light and pressure wave in a material, or equivalently in quantum theory terms between photons and phonons, gives some glimpses of the atomic structure of the solid and of its vibration modes. For an applied engineer, the same phenomenon may be put to good use as a sensing mechanism for distributed measurements, thanks to the dependence of the scattered light on external parameters such as the temperature, the pressure or the strain applied to the fiber. As far as temperature measurements are concerned, Brillouin-based distributed sensors have progressively gained wide recognition as efficient systems, even if their rather high cost still restricts the number of their applications. Yet they are generally used in a relatively narrow temperature range around the usual ambient temperature; in this domain, the frequency of the scattered light incre...

  1. Elastic properties of aspirin in its crystalline and glassy phases studied by micro-Brillouin scattering

    Science.gov (United States)

    Ko, Jae-Hyeon; Lee, Kwang-Sei; Ike, Yuji; Kojima, Seiji

    2008-11-01

    The acoustic waves propagating along the direction perpendicular to the (1 0 0) cleavage plane of aspirin crystal were investigated using micro-Brillouin spectroscopy from which C11, C55 and C66 were obtained. The temperature dependence of the longitudinal acoustic waves could be explained by normal anharmonic lattice models, while the transverse acoustic waves showed an abnormal increase in the hypersonic attenuation at low temperatures indicating their coupling to local remnant dynamics. The sound velocity as well as the attenuation of the longitudinal acoustic waves of glassy aspirin showed a substantial change at ˜235 K confirming a transition from glassy to supercooled liquid state in vitreous aspirin.

  2. Realistic model for the stimulated Brillouin scattering instability

    International Nuclear Information System (INIS)

    The purpose of this work is to present a new model describing the stimulated Brillouin scattering instability in an inhomogeneous plasma. This model, called the harmonic decomposition method is based on the decomposition of plasma characteristics like density and speed into their short and long wavelengths components. This model describes: the propagation of the incident and reflected laser wave, the evolution of the sound wave and the hydrodynamic evolution of the plasma on a large scale. The first chapter recalls theoretical concepts concerning the stimulated Brillouin scattering, the filamentation and auto-focusing and introduces the harmonic decomposition method. The second chapter deals with the validation of this method through a comparison with an exact hydrodynamics model. The third chapter presents the interpretation of laser-plasma experiments with this new method. The fourth chapter presents different ways of improving the description by taking into account kinetics effects or a better decomposition of the sound wave. (A.C.)

  3. Noise and dynamics in forward Brillouin interactions

    Science.gov (United States)

    Kharel, P.; Behunin, R. O.; Renninger, W. H.; Rakich, P. T.

    2016-06-01

    In this paper, we explore the spatiotemporal dynamics of spontaneous and stimulated forward Brillouin scattering. This general treatment incorporates the optomechanical coupling produced by boundary-induced radiation pressures (boundary motion) and material-induced electrostrictive forces (photoelastic effects), permitting straightforward application to a range of emerging micro- and nanoscale optomechanical systems. Through a self-consistent fully coupled nonlinear treatment, developed within a general Hamiltonian framework, we establish the connection between the power spectral density of spontaneously scattered light in forward Brillouin interactions and the nonlinear coupling strength. We show that, in sharp contrast to backward Brillouin scattering, noise-initiated stimulated forward Brillouin scattering is forbidden in the majority of experimental systems. In fact, the single-pass gain, which characterizes the threshold for energy transfer in back-scattering processes, is negative for a large class of forward Brillouin devices. Beyond this frequent experimental case, we explore mechanisms for dispersive symmetry breaking that lead to amplification and dynamics reminiscent of backward Brillouin scattering.

  4. Stimulated Brillouin Scatter in a Magnetized Ionospheric Plasma

    International Nuclear Information System (INIS)

    High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (fCI) or an electrostatic ion cyclotron (EIC) wave just above fCI can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.

  5. Stimulated Brillouin scatter in a magnetized ionospheric plasma.

    Science.gov (United States)

    Bernhardt, P A; Selcher, C A; Lehmberg, R H; Rodriguez, S P; Thomason, J F; Groves, K M; McCarrick, M J; Frazer, G J

    2010-04-23

    High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f(CI)) or an electrostatic ion cyclotron (EIC) wave just above f(CI) can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency. PMID:20482059

  6. Transformation optics simulation method for stimulated Brillouin scattering

    CERN Document Server

    Zecca, Roberto; Smith, David R; Larouche, Stéphane

    2016-01-01

    We develop a novel approach to enable the full-wave simulation of stimulated Brillouin scattering and related phenomena in a frequency-domain, finite-element environment. The method uses transformation optics techniques to implement a time-harmonic coordinate transform that reconciles the different frames of reference used by electromagnetic and mechanical finite-element solvers. We show how this strategy can be successfully applied to bulk and guided systems, comparing the results with the predictions of established theory.

  7. Thermally induced amorphous to crystalline transformation of argon ion bombarded GaAs studied with surface Brillouin and Raman scattering

    Science.gov (United States)

    Jakata, K.; Wamwangi, D. M.; Sumanya, C.; Mathe, B. A.; Erasmus, R. M.; Naidoo, S. R.; Comins, J. D.

    2012-09-01

    Surface Brillouin scattering (SBS) and Raman spectroscopy have been used to investigate the recrystallisation of an amorphous layer of GaAs created on single crystal (0 0 1) GaAs by ion bombardment with 100 keV argon ions with a fluence of 5 × 1016 ions/cm2 at a temperature of ˜65 °C. Samples were isochronally annealed and the light scattering measurements were performed after each annealing step. The SBS studies confirm structural changes resulting in continuous stiffening of the layer beginning above 200 °C and finally attaining a maximum value above 500 °C. The Raman studies show evidence of full recrystallisation above 500 °C, with the appearance of both LO and TO peaks indicating that the reformed layer is polycrystalline.

  8. Stimulated Brillouin scattering in a two-level system

    Science.gov (United States)

    Postan, A.; Rai, Jagdish; Bowden, Charles M.

    1992-03-01

    Resonances in the interaction of a saturable two-level system with stimulated Brillouin scattering are discussed. These resonances appear due to the coupling between the two-level system and the resonant acoustic waves that are excited in the host substance by a coherent electromagnetic field of two mutually detuned, counterpropagating laser beams. Results for sodium vapor mixed with nitrogen buffer gas are presented.

  9. Stimulated Brillouin scattering enhancement in silicon inverse opal waveguides

    OpenAIRE

    Smith, M. J. A.; Wolff, C; Sterke, C. Martijn de; Lapine, M.; Kuhlmey, B. T.; Poulton, C. G.

    2016-01-01

    Silicon is an ideal material for on-chip applications, however its poor acoustic properties limit its performance for important optoacoustic applications, particularly for Stimulated Brillouin Scattering (SBS). We theoretically show that silicon inverse opals exhibit a strongly improved acoustic performance that enhances the bulk SBS gain coefficient by more than two orders of magnitude. We also design a waveguide that incorporates silicon inverse opals and which has SBS gain values that are ...

  10. Dynamic Microwave Photonic Filter Using Separate Carrier Tuning Based on Stimulated Brillouin Scattering in Fibers

    OpenAIRE

    Sancho J.; Chin S.; Sagues M.; Loayssa A.; Lloret J.; Gasulla I.; Sales S.; Thevenaz L.; Capmany J.

    2010-01-01

    Dynamic reconfiguration of a microwave photonic filter by tuning its basic delay based on stimulated Brillouin scattering-induced slow light and optical phase shift of the optical carrier is experimentally implemented. The measurements confirm that the free spectral range of the filter changes when a Brillouin pump is applied. These results demonstrate the potential of the separate carrier technique in microwave photonics applications.

  11. Effect of collisions on amplification of laser beams by Brillouin scattering in plasmas

    Science.gov (United States)

    Humphrey, K. A.; Trines, R. M. G. M.; Fiuza, F.; Speirs, D. C.; Norreys, P.; Cairns, R. A.; Silva, L. O.; Bingham, R.

    2013-10-01

    We report on particle in cell simulations of energy transfer between a laser pump beam and a counter-propagating seed beam using the Brillouin scattering process in uniform plasma including collisions. The results presented show that the ion acoustic waves excited through naturally occurring Brillouin scattering of the pump field are preferentially damped without affecting the driven Brillouin scattering process resulting from the beating of the pump and seed fields together. We find that collisions, including the effects of Landau damping, allow for a more efficient transfer of energy between the laser beams, and a significant reduction in the amount of seed pre-pulse produced.

  12. Effect of collisions on amplification of laser beams by Brillouin scattering in plasmas

    International Nuclear Information System (INIS)

    We report on particle in cell simulations of energy transfer between a laser pump beam and a counter-propagating seed beam using the Brillouin scattering process in uniform plasma including collisions. The results presented show that the ion acoustic waves excited through naturally occurring Brillouin scattering of the pump field are preferentially damped without affecting the driven Brillouin scattering process resulting from the beating of the pump and seed fields together. We find that collisions, including the effects of Landau damping, allow for a more efficient transfer of energy between the laser beams, and a significant reduction in the amount of seed pre-pulse produced

  13. A New Approach to Cascaded Stimulated Brillouin Scattering

    CERN Document Server

    Dong, Mark

    2015-01-01

    We present a novel approach to cascaded stimulated Brillouin scattering and frequency comb generation in which the multitude of interacting pump, Stokes, and anti-Stokes optical fields are described by a single forward wave and a single backward wave at a single carrier frequency. The envelopes of these two waves are modulated through coupling to a single acoustic oscillation and through four-wave mixing. Starting from a single pump field, we observe the emergence of a comb of frequencies as the intensity is increased. The set of three differential equations derived here are sufficient to describe the generation of any number of Brillouin sidebands in oscillator systems that would have required hundreds of coupled equations in the standard approach. We test the new approach on some published experiments and find excellent agreement with the results.

  14. Dual Raman-Brillouin Microscope for Chemical and Mechanical Characterization and Imaging.

    Science.gov (United States)

    Traverso, Andrew J; Thompson, Jonathan V; Steelman, Zachary A; Meng, Zhaokai; Scully, Marlan O; Yakovlev, Vladislav V

    2015-08-01

    We present a unique confocal microscope capable of measuring the Raman and Brillouin spectra simultaneously from a single spatial location. Raman and Brillouin scattering offer complementary information about a material's chemical and mechanical structure, respectively, and concurrent monitoring of both of these spectra would set a new standard for material characterization. We achieve this by applying recent innovations in Brillouin spectroscopy that reduce the necessary acquisition times to durations comparable to conventional Raman spectroscopy while attaining a high level of spectral accuracy. To demonstrate the potential of the system, we map the Raman and Brillouin spectra of a molded poly(ethylene glycol) diacrylate (PEGDA) hydrogel sample in cyclohexane to create two-dimensional images with high contrast at microscale resolutions. This powerful tool has the potential for very diverse analytical applications in basic science, industry, and medicine.

  15. High temperatures and high pressures Brillouin scattering studies of liquid H(2)O+CO(2) mixtures.

    Science.gov (United States)

    Qin, Junfeng; Li, Min; Li, Jun; Chen, Rongyan; Duan, Zhenhao; Zhou, Qiang; Li, Fangfei; Cui, Qiliang

    2010-10-21

    The Brillouin scattering spectroscopy studies have been conducted in a diamond anvil cell for a liquid mixtures composed of 95 mol % H(2)O and 5 mol % CO(2) under high temperatures and pressures. The sound velocity, refractive index, density, and adiabatic bulk modulus of the H(2)O+CO(2) mixtures were determined under pressures up to the freezing point at 293, 453, and 575 K. It is found from the experiment that sound velocities of the liquid mixture are substantially lower than those of pure water at 575 K, but not at lower temperatures. We presented an empirical relation of the density in terms of pressure and temperature. Our results show that liquid H(2)O+CO(2) mixtures are more compressible than water obtained from an existing equation of state of at 453 and 575 K. PMID:20969409

  16. Theory of magnetic surface anisotropy and exchange effects in the Brillouin scattering of light by magnetostatic spin waves (invited)

    Science.gov (United States)

    Rado, G. T.; Hicken, R. J.

    1988-04-01

    A new theory of the Brillouin shift in the inelastic scattering of light by magnetostatic spin waves is presented. Contrary to previous work, the present calculations do include exchange effects and treat the magnetic surface anisotropy constants Ks and Kss directly rather than via the stratagem of effective volume anisotropies. The experimental data for {110} Fe on W are explained about as well by the present theory as by previous work. A detailed analysis reveals the previously unnoticed fact that the signs of Ks and Kss for (1¯10) Fe on W are opposite to those for (1¯10) Fe on GaAs. Some new spin-wave modes arising from exchange are predicted and shown to occur outside the frequency range which has been investigated experimentally. A quantitative explanation is proposed for the occasional applicability of a theory based on effective volume anisotropies and zero exchange.

  17. Cascaded gain fibers for increasing output power and the stimulated Brillouin scattering threshold of narrow linewidth fiber Raman amplifiers.

    Science.gov (United States)

    Nagel, J A; Temyanko, V; Dobler, J T; Likhachev, M E; Bubnov, M M; Dianov, E M; Peyghambarian, N

    2016-05-20

    We show both experimentally and theoretically a method to increase the stimulated Brillouin scattering (SBS) threshold and output power of narrow linewidth fiber Raman amplifiers. This method employs two or more fibers with varying concentrations of the Raman gain material dopant such as GeO2 or P2O5 in silicate-based glasses. These fibers are then cascaded to form an amplifier gain stage, disrupting the buildup of SBS that normally occurs in single continuous fibers. The numerical model shown is applicable to arbitrary amplifier systems for gain stage optimization and increased power scaling. We give experimental results for phosphosilicate fibers that agree well with simulation predictions that support the numerical model used. PMID:27411133

  18. The elastic constants and related properties of the epsilon polymorph of the energetic material CL-20 determined by Brillouin scattering

    Science.gov (United States)

    Haycraft, James J.

    2009-12-01

    The acoustic phonons of the epsilon polymorph of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.05,9.03,11] dodecane (ɛ-CL-20) have been studied using Brillouin scattering spectroscopy. Analysis of the acoustic phonon velocities allowed determination of the complete stiffness tensor for this energetic material. The results are compared to a theoretical determination of the ɛ-CL-20 elastic constants, bulk moduli, and shear moduli. The observed ordering of elastic constants, C22>C33>C11, is noted to be different from other nitramine energetic materials. Finally, the elasticity of ɛ-CL-20 is compared to recently published reports on cyclotrimethylene trinitramine's (RDX) elasticity and the beta polymorph of cyclotetramethylene tetranitramine's (β-HMX) elasticity.

  19. True Time Delay on tunable Microwave Photonic Filter based on Stimulated Brillouin Scattering in fibers

    OpenAIRE

    Sancho J.; Chin S.; Sagues M.; Loayssa A.; Lloret J.; Gasulla I.; Sales S.; Thevenaz L.; Capmany J.

    2010-01-01

    A dynamically reconfigurable Microwave Photonic Filter based on True Time Delay generated by Stimulated Brillouin Scattering in optical fibers and separate phase shift of the optical carrier has been experimentally demonstrated, resulting in a flexible tunable Free Spectral Range.

  20. Self-Advanced Propagation of Light Pulse in an Optical Fiber Based on Brillouin Scattering

    OpenAIRE

    Chin, Sanghoon; Gonzalez-Herraez, Miguel; Thévenaz, Luc

    2007-01-01

    We propose a novel method to realize self-induced fast light and signal advancement with no distinct pump source in optical fibers, based on stimulated Brillouin scattering. This scheme will be helpful for real application systems.

  1. Magnetostatic wave device characterization by Brillouin light scattering

    Science.gov (United States)

    Patton, Carl E.; Srinivasan, Gopalan

    1989-02-01

    This final report summarizes the important results of the Brillouin light scattering investigations of magnetic excitations in magnetostatic wave (MSW) devices which were carried out under the RADC contract. The key accomplishments were the observation and characterization of surface waves, forward volume waves, backward volume waves, parametric spin waves, and a new type of evanescent surface wave in yttrium iron garnet film MSW devices. The propagation characteristics for surface wave in Fe, Co-Cr, and Ni-Fe films were also examined, in order to investigate the possible use of such films in MSW devices. Details on technical publications and participating personnel during this contract period are also provided.

  2. Stimulated Brillouin processes in crystals and glasses

    International Nuclear Information System (INIS)

    The basic physics and material properties needed to describe and predict the Brillouin gain for a variety of materials have been investigated. Lawrence Livermore National Laboratory (LLNL) has identified transverse stimulated Brillouin scattering (SBS) as an important limiting mechanism in high power laser fusion systems. At sufficiently high laser intensities, SBS drives acoustic vibrations that can damage optical components. SRI has performed measurements and developed the corresponding theory for stimulated Brillouin gain spectroscopy in anisotropic crystals. Absolute Brillouin steady-state gain coefficients, linewidths, and frequency shifts have been determined at 532 nm for a number of optical materials of interest to LLNL. This knowledge can be used to select optical materials and devise suppression schemes that will allow much higher laser fluences to be used in laser fusion

  3. Stimulated Brillouin scattering enhancement in silicon inverse opal waveguides

    CERN Document Server

    Smith, M J A; de Sterke, C Martijn; Lapine, M; Kuhlmey, B T; Poulton, C G

    2016-01-01

    Silicon is an ideal material for on-chip applications, however its poor acoustic properties limit its performance for important optoacoustic applications, particularly for Stimulated Brillouin Scattering (SBS). We theoretically show that silicon inverse opals exhibit a strongly improved acoustic performance that enhances the bulk SBS gain coefficient by more than two orders of magnitude. We also design a waveguide that incorporates silicon inverse opals and which has SBS gain values that are comparable with chalcogenide glass waveguides. This research opens new directions for opto-acoustic applications in on-chip material systems.

  4. Two-dimensional studies of stimulated Brillouin scattering, filamentation, and self-focusing instabilities of laser light in plasmas

    International Nuclear Information System (INIS)

    The parametric interaction of an intense laser beam with ion plasma modes in a two-dimensional Cartesian geometry has been studied for the first time by avoiding the paraxial optics approximation. This model allows investigation of the competition between forward, sideward, and backward stimulated Brillouin scattering (SBS) along with filamentation and self-focusing instabilities. It is shown that the SBS saturation level, the angular distribution of transmitted and scattered light, and their temporal dependence are governed mainly by two control parameters: the backward SBS gain coefficient G, and the ratio αsf of the incident beam power to its critical value for the onset of self-focusing. In the case of large values of G approx-gt 15, backward SBS dominates and prevents both self-focusing and forward SBS. For smaller values of G, the interaction exhibits a complex oscillatory behavior, which corresponds to the competition between backward and forward SBS for αsf approx-lt 1, and involves also self-focusing for higher beam intensities

  5. Stimulated Brillouin and Raman scattering from a randomized laser beam in large inhomogeneous collisional plasmas. I. Experiment

    Science.gov (United States)

    Fuchs, J.; Labaune, C.; Depierreux, S.; Tikhonchuk, V. T.; Baldis, H. A.

    2000-11-01

    Experiments have been conducted at the LULI (Laboratoire pour l'Utilisation des Lasers Intenses) multibeam laser facility to study in detail stimulated Brillouin (SBS) and Raman (SRS) scattering from an intense (mean average intensity up to 1014W/cm2) long (600 ps full width at half-maximum) laser beam interacting with thin exploded plastic foils. The plasmas are well characterized and the vacuum laser intensity distribution is well known due to using either random phase plates or polarization smoothing. Direct and simultaneous Thomson scattering measurements of the associated plasma waves allow us to obtain detailed information about the SBS and SRS temporal evolution and spatial localization. These data are being used to benchmark a statistical model of SBS and SRS from self-focused speckles. The results of this comparison will be presented in a companion paper. The analysis shows that both SBS and SRS are originated from self-focused speckles and reveals that plasma heating has an important effect on speckle self-focusing.

  6. Resonance Raman scattering and excitonic spectra in TlInS{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zalamai, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, 5 Academy Street, 2028 Chisinau, Republic of Moldova (Moldova, Republic of); Stamov, I.G. [T.G. Shevchenko State University of Pridnestrovie, 25 Oktyabrya Street 107, 3300 Tiraspol, Republic of Moldova (Moldova, Republic of); Syrbu, N.N., E-mail: sirbunn@yahoo.com [Technical University of Moldova, 168 Stefan cel Mare Avenue, 2004 Chisinau, Republic of Moldova (Moldova, Republic of); Ursaki, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, 5 Academy Street, 2028 Chisinau, Republic of Moldova (Moldova, Republic of); Dorogan, V. [Technical University of Moldova, 168 Stefan cel Mare Avenue, 2004 Chisinau, Republic of Moldova (Moldova, Republic of)

    2015-04-15

    The excitons ground and excited states for E∥a and E∥b polarizations in absorption and reflection spectra of TlInS{sub 2} crystals were detected. The fundamental parameters of excitons and bands were determined at k=0. The resonance Raman spectra were investigated in the region of excitons transitions. The resonance Raman scattering spectra with participation of optical phonons that are active at the center of Brillouin zone were identified. The Raman scattering in Y(YX)Z and Y(ZX)Z geometries at 10 K with excitation by He–Ne laser was researched. Energies of phonons with A{sub g} and B{sub g} symmetries were determined. It was shown that the number of modes at 10 K was two times lower than expected according to theoretical calculations. - Highlights: • The resonance Raman scattering in geometry Y(YX)Z and Y(ZX)Z at 10 K was investigated. • Energies of phonons with A{sub g} and B{sub g} symmetries were determined. • The experimental and theoretical calculations completely conform if crystals are described by symmetry group D{sub 4h}{sup 15}. • The main parameters of excitons and bands were determined. • The model of electron transitions in k=0 was suggested.

  7. True-time delay line with separate carrier tuning using dual-parallel MZM and stimulated Brillouin scattering-induced slow light.

    Science.gov (United States)

    Li, Wei; Zhu, Ning Hua; Wang, Li Xian; Wang, Jia Sheng; Liu, Jian Guo; Liu, Yu; Qi, Xiao Qiong; Xie, Liang; Chen, Wei; Wang, Xin; Han, Wei

    2011-06-20

    We experimentally demonstrate a novel tunable true-time delay line with separate carrier tuning using dual-parallel Mach-Zehnder modulator and stimulated Brillouin scattering-induced slow light. The phase of the optical carrier can be continuously and precisely controlled by simply adjusting the dc bias of the dual-parallel Mach-Zehnder modulator. In addition, both the slow light and single-sideband modulation can be simultaneously achieved in the stimulated Brillouin scattering process with three types of configuration. Finally, the true-time delay technique is clearly verified by a two-tap incoherent microwave photonic filter as the free spectral range of the filter is changed. PMID:21716468

  8. Threshold level and gain of forward stimulated Brillouin scattering in a forward pumped s-band discrete DCF fibers Raman amplifier

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-feng; ZHANG Zai-xuan; DAI Bi-zhi; LI Chen-xia; INSOO S.KIM

    2006-01-01

    Amplification effect of forward stimulated Brillouin scattering (SBS) lines on the forward pumped s-band discrete DCF fiber Raman amplifier (FRA) has been studied.Pump threshold power of the forward first order Stokes SBS (FSB1- ),second order Stokes SBS (FSB2-) and third order SBS (FSB3-) in the forward pumped FRA are 1.5 mW,1.4 mW and 1.7 mW,respectively.The Stokes SBS lines are amplified by FRA and fiber Brillouin amplifier (FBA) at the same time.Gain of amplification is given as GA=GR·GB,where GR is Raman gain and GB is Brillouin gain.Saturation gain of FSB1-,FSB2- and FSB3- are about 52 dB,65 dB and 65 dB,respectively.The saturation Raman gain of 10 km DCF forward FRA is about 14 dB,so Brillouin gain of FSB1-,FSB2- and FSB3- are about 38 dB,51 dB and 51 dB,respectively.The forward cascaded SBS lines have been observed.

  9. Initiation and Saturation of Backward Stimulated Raman and Brillouin Scatter in Single Speckles: Influence of Scattered-Light Seeds and Collisional Heating

    Science.gov (United States)

    Yin, L.; Albright, B. J.; Rose, H. A.; Bowers, K. J.; Bergen, B.; Finnegan, S. M.

    2009-11-01

    A suite of 2D and 3D PIC simulations of backward stimulated Raman and Brillouin scattering (SRS and SBS) in ICF hohlraum and Trident plasma have been performed on the heterogeneous multi-core supercomputer, Roadrunner. These calculations reveal that the physics governing the nonlinear saturation of SRS in 3D is consistent with that of prior 2D studies [L. Yin, et al. Phys. Rev. Lett., 99, 265004, 2007], but with important differences arising from enhanced diffraction and side loss in 3D compared with 2D. In addition to wavefront bowing of electron plasma waves (EPW), we find that EPW self-focusing also exhibits loss of angular coherence by formation of a filament necklace, a process not available in 2D. These processes in higher dimensions increase the side-loss rate of trapped electrons, increase wave damping, decrease source coherence for backscattered light, and fundamentally limit how much backscatter can occur from a laser speckle. The SRS onset threshold is lower if initiated by SRS seeds compared with the onset threshold if SRS is initiated by thermal electron density fluctuations alone. Furthermore, we show that the presence or absence of SBS may be sensitively determined by collisional heating and transverse electron temperature variations.

  10. Coherent Rayleigh-Brillouin scattering as a flow diagnostic technique

    Energy Technology Data Exchange (ETDEWEB)

    Graul, J. S.; Lilly, T. C. [Department of Mechanical and Aerospace Engineering, University of Colorado Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918 (United States)

    2014-12-09

    Broadband coherent Rayleigh-Brillouin scattering (CRBS) was used to measure translational gas temperatures for nitrogen at the ambient pressure of 0.8 atm using a purpose-built Fabry-Perot etalon spectrometer. Temperatures derived from the CRBS spectral analysis were compared with experimentally-measured temperatures, and were found to be, on average, within 2% of the experimentally-measured value. Axial flow velocities from a double jet at a pressure ratio of 0.38 were also measured by looking at the Doppler shift of the CRBS line shape. With recent developments in chirped laser technology and the capacity of CRBS to simultaneously provide thermodynamic and bulk flow information, the CRBS line shape acquisition and analysis technique presented here may allow for future time-resolved, characterization of aerospace flows.

  11. Study of a dynamical plasma response in laser filamentation induced in silica glasses in presence of stimulated Brillouin scattering and in KDP crystals

    International Nuclear Information System (INIS)

    This thesis deals with the role of an inertial plasma response produced by laser pulses in self-focusing regime. This phenomenon is coupled with Brillouin nonlinearities for nanosecond pulses in silica glasses and excites various ionization channels for femtosecond pulses. We start by deriving the propagation equations accounting for filamentation due to optical Kerr effect and stimulated Brillouin scattering in the presence of a dynamical plasma response. Then, we present numerical results on the nonlinear propagation of large-scaled laser beams. These results validate the anti-Brillouin system adopted on the MegaJoule laser (LMJ). Next, we present numerical and theoretical results on filamentation of nanosecond light pulses operating in the ultraviolet and infrared range in fused silica. Emphasis is put on the action of a dynamical plasma response. For a single wave, we develop a variational analysis which reproduces global propagation features for a quasistationary balance between self-focusing and plasma defocusing. However, such a quasistationary balance breaks up through modulational instabilities induced by plasma feedback on the pump wave. We show that phase modulations suppress both stimulated Brillouin scattering and plasma instabilities. Finally, we study numerically the nonlinear propagation of femtosecond pulses in fused silica and KDP. First, we show that the presence of defects involving less photons for exciting electrons from the valence band to the conduction band promotes higher filamentation intensity levels. Secondly, we compare the filamentation dynamics in silica and KDP crystal. The ionization model for KDP crystals takes into account the presence of defects and the electron-hole dynamics. We show that the propagation dynamics in silica and KDP are almost identical at equivalent ratios of input power over the critical power for self-focusing. (author)

  12. Bunching of temporal cavity solitons via forward Brillouin scattering

    CERN Document Server

    Erkintalo, Miro; Jang, Jae K; Coen, Stéphane; Murdoch, Stuart G

    2015-01-01

    We report on the experimental observation of bunching dynamics with temporal cavity solitons in a continuously-driven passive fibre resonator. Specifically, we excite a large number of ultrafast cavity solitons with random temporal separations, and observe in real time how the initially random sequence self-organizes into regularly-spaced aggregates. To explain our experimental observations, we develop a simple theoretical model that allows long-range acoustically-induced interactions between a large number of temporal cavity solitons to be simulated. Significantly, results from our simulations are in excellent agreement with our experimental observations, strongly suggesting that the soliton bunching dynamics arise from forward Brillouin scattering. In addition to confirming prior theoretical analyses and unveiling a new cavity soliton self-organization phenomenon, our findings elucidate the manner in which sound interacts with large ensembles of ultrafast pulses of light.

  13. Bayesian approach to the analysis of neutron Brillouin scattering data on liquid metals.

    Science.gov (United States)

    De Francesco, A; Guarini, E; Bafile, U; Formisano, F; Scaccia, L

    2016-08-01

    When the dynamics of liquids and disordered systems at mesoscopic level is investigated by means of inelastic scattering (e.g., neutron or x ray), spectra are often characterized by a poor definition of the excitation lines and spectroscopic features in general and one important issue is to establish how many of these lines need to be included in the modeling function and to estimate their parameters. Furthermore, when strongly damped excitations are present, commonly used and widespread fitting algorithms are particularly affected by the choice of initial values of the parameters. An inadequate choice may lead to an inefficient exploration of the parameter space, resulting in the algorithm getting stuck in a local minimum. In this paper, we present a Bayesian approach to the analysis of neutron Brillouin scattering data in which the number of excitation lines is treated as unknown and estimated along with the other model parameters. We propose a joint estimation procedure based on a reversible-jump Markov chain Monte Carlo algorithm, which efficiently explores the parameter space, producing a probabilistic measure to quantify the uncertainty on the number of excitation lines as well as reliable parameter estimates. The method proposed could turn out of great importance in extracting physical information from experimental data, especially when the detection of spectral features is complicated not only because of the properties of the sample, but also because of the limited instrumental resolution and count statistics. The approach is tested on generated data set and then applied to real experimental spectra of neutron Brillouin scattering from a liquid metal, previously analyzed in a more traditional way. PMID:27627410

  14. Bayesian approach to the analysis of neutron Brillouin scattering data on liquid metals

    Science.gov (United States)

    De Francesco, A.; Guarini, E.; Bafile, U.; Formisano, F.; Scaccia, L.

    2016-08-01

    When the dynamics of liquids and disordered systems at mesoscopic level is investigated by means of inelastic scattering (e.g., neutron or x ray), spectra are often characterized by a poor definition of the excitation lines and spectroscopic features in general and one important issue is to establish how many of these lines need to be included in the modeling function and to estimate their parameters. Furthermore, when strongly damped excitations are present, commonly used and widespread fitting algorithms are particularly affected by the choice of initial values of the parameters. An inadequate choice may lead to an inefficient exploration of the parameter space, resulting in the algorithm getting stuck in a local minimum. In this paper, we present a Bayesian approach to the analysis of neutron Brillouin scattering data in which the number of excitation lines is treated as unknown and estimated along with the other model parameters. We propose a joint estimation procedure based on a reversible-jump Markov chain Monte Carlo algorithm, which efficiently explores the parameter space, producing a probabilistic measure to quantify the uncertainty on the number of excitation lines as well as reliable parameter estimates. The method proposed could turn out of great importance in extracting physical information from experimental data, especially when the detection of spectral features is complicated not only because of the properties of the sample, but also because of the limited instrumental resolution and count statistics. The approach is tested on generated data set and then applied to real experimental spectra of neutron Brillouin scattering from a liquid metal, previously analyzed in a more traditional way.

  15. Widely tunable linear-cavity multiwavelength fiber laser with distributed Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    M. Ajiya; M. H. Al-Mansoori; M. A. Mahdi

    2011-01-01

    We demonstrate a multiple wavelength Brillouin/erbium fiber laser in a linear cavity configuration. The laser cavity is made up of a fiber loop mirror on one end of the resonator and a virtual mirror generated from the distributed stimulated Brillouin scattering effect on the other end. Due to the weak reflectivity provided by the virtual mirror, self-lasing cavity modes are completely suppressed from the laser cavity. At Brillouin pump and 1480-nm pump powers of 2 and 130 mW, respectively, 11 channels of the demonstrated laser with an average total power of 7.13 dBm can freely be tuned over a span of 37-nm wavelength from 1530 to 1567 nm.%@@ We demonstrate a multiple wavelength Brillouin/erbium fiber laser in a linear cavity configuration.The laser cavity is made up of a fiber loop mirror on one end of the resonator and a virtual mirror generated from the distributed stimulated Brillouin scattering effect on the other end.Due to the weak reflectivity provided by the virtual mirror, self-lasing cavity modes are completely suppressed from the laser cavity.At Brillouin pump and 1480-nm pump powers of 2 and 130 mW, respectively, 11 channels of the demonstrated laser with an average total power of 7.13 dBm can freely be tuned over a span of 37-nm wavelength from 1530 to 1567 nm.

  16. Tunable narrowband microwave photonic filter created by stimulated Brillouin scattering from a silicon nanowire.

    Science.gov (United States)

    Casas-Bedoya, Alvaro; Morrison, Blair; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J

    2015-09-01

    We demonstrate the first, to the best of our knowledge, functional signal processing device based on stimulated Brillouin scattering in a silicon nanowire. We use only 1 dB of on-chip stimulated Brillouin scattering gain to create an RF photonic notch filter with 48 dB of suppression, 98 MHz linewidth, and 6 GHz frequency tuning. This device has potential applications in on-chip microwave signal processing and establishes the foundation for the first CMOS-compatible high-performance RF photonic filter. PMID:26368735

  17. Comparative analysis of characteristic electron energy loss spectra and inelastic scattering cross-section spectra of Fe

    Science.gov (United States)

    Parshin, A. S.; Igumenov, A. Yu.; Mikhlin, Yu. L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2016-05-01

    The inelastic electron scattering cross section spectra of Fe have been calculated based on experimental spectra of characteristic reflection electron energy loss as dependences of the product of the inelastic mean free path by the differential inelastic electron scattering cross section on the electron energy loss. It has been shown that the inelastic electron scattering cross-section spectra have certain advantages over the electron energy loss spectra in the analysis of the interaction of electrons with substance. The peaks of energy loss in the spectra of characteristic electron energy loss and inelastic electron scattering cross sections have been determined from the integral and differential spectra. It has been shown that the energy of the bulk plasmon is practically independent of the energy of primary electrons in the characteristic electron energy loss spectra and monotonically increases with increasing energy of primary electrons in the inelastic electron scattering cross-section spectra. The variation in the maximum energy of the inelastic electron scattering cross-section spectra is caused by the redistribution of intensities over the peaks of losses due to various excitations. The inelastic electron scattering cross-section spectra have been analyzed using the decomposition of the spectra into peaks of the energy loss. This method has been used for the quantitative estimation of the contributions from different energy loss processes to the inelastic electron scattering cross-section spectra of Fe and for the determination of the nature of the energy loss peaks.

  18. Nonlinear phase shifts of modulated light waves with slow and superluminal group delay in stimulated Brillouin scattering.

    Science.gov (United States)

    Arditi, Tal; Granot, Er'el; Sternklar, Shmuel

    2007-09-15

    Brillouin amplification with counterpropagating modulated pump and Stokes light leads to nonlinear modulation-phase shifts of the interacting intensity waves. This is due to a partial transformation of the nonmodulated light component at the input into modulated light at the output as a result of a mixing process with the counterpropagating modulated component of the pump and results in an advance or delay of the input modulation. This occurs for interactions over less than half of a modulation wavelength. Milliwatts of power in a kilometer of standard single-mode fiber give significant tunability of the modulation phase.

  19. Investigation of nonlinear processes associated with stimulated Brillouin scattering in an underdense and extended plasma

    International Nuclear Information System (INIS)

    In our experiment, the plasma was performed by means of a Z-pinch. Although a plasma near or above the critical density could have been produced, our experiment was deliberately restricted to underdense plasma as a) our interest was to investigate similar situations as encountered in the large extended coronal region of laser-pellet interaction which may endanger the prospects of laser fusion, b) it is readily accessible to various diagnostic methods, and, c) there is sufficient experimental data and theory availabe for comparison. After a brief introduction of the subject, the theory of laser-induced parametric instabilities, as well as various saturation mechanisms are discussed in the second chapter. The third Chapter contains the experimental details of the complete CO2 laser system, the Z-pinch, and the laser plasma interaction experiment. Experimental results are reported in the next Chapter and are analyzed in the light of predictions discussed in the second Chapter. A comparison of our results with other experiments is made in Chapter 5, and the discrepancies are explained on the basis of a simple model. The last Chapter sums up the entire work. For a better understanding of the subject, the physics of the laser has been given in Appendix. (orig./HT)

  20. High-pressure Brillouin scattering in a simple molecular system

    CERN Document Server

    Shimizu, H

    2002-01-01

    Recent developments in high-pressure in situ Brillouin spectroscopy of a simple molecular system are reviewed by demonstrating experimental and analytical methods for the study of acoustic velocities in any direction, adiabatic elastic constants, and elastic anisotropy. Detailed applications to solid argon (Ar) are presented, at pressures up to 70 GPa in a diamond anvil cell, using recently developed approaches that combine the method of in situ Brillouin spectroscopy, for a single crystal of Ar up to 4 GPa, and the envelope method applied to both longitudinal acoustic and transverse acoustic modes, for recrystallized Ar between 4 and 70 GPa.

  1. Performance of the distributed Brillouin sensor: Benefits and penalties due to pump depletion

    Science.gov (United States)

    Ravet, Fabien

    Disaster prevention in civil infrastructures requires the use of techniques that allow temperature and strain measurements in real time over lengths of a few meters to tens of kilometres. The distributed Brillouin sensor (DBS) technique has the advantage to combine all these characteristics. The sensing mechanism of the DBS involves the interaction of two counter-propagating lightwaves, the Stokes and the pump, in an optical fibre. Spatial information is obtained through time domain analysis. The sensing data are recorded from the measurement of the pump depletion. We explore the benefits and the drawbacks of this approach and show that there is a power range for which the sensing performances are optima. To achieve that goal, Brillouin fibre generator (BFG) and amplifier (BFA) were studied leading to the derivation of a threshold definition for the BFA, which is the configuration of the DBS. Within that context, numerical and analytical models describing the stimulated Brillouin scattering (SBS) interaction are introduced and validated experimentally. Even if pump depletion is carefully controlled, the Brillouin spectrum shape, and hence the sensor performance, still depend on the sensing parameters such as power, pulse and fibre characteristics. We use a signal processing method grounded in the physics of Brillouin scattering. An analytical approximation, valid for the optimum sensing region, reconstructs the Brillouin spectrum distribution from input sensing parameters and measured data. These data are obtained with a spectrum analysis methodology, based on three original tools: the Rayleigh equivalent criterion, the lengthstress diagram, and the spectrum form factors. This methodology has been successfully used on experimental spectra. The DBS and the signal processing approach were then used to monitor the structural changes in steel pipes and in a composite column, all subjected to heavy loads. The DBS measured the strain distribution of those structures

  2. Modeling of stimulated Brillouin scattering in expanding plasmas

    Science.gov (United States)

    Hüller, S.; Masson-Laborde, P. E.; Pesme, D.; Labaune, C.; Bandulet, H.

    2008-05-01

    Numerical simulations of mm-size expanding plasmas have been performed in comparison with recent experiments at the LULI facility. The features of Stimulated Brillouin Scattering (SBS) are studied for an intense mono-speckle laser beam in continuation of previous work on optically smoothed laser beams. Very good agreement between the theoretical-numerical modeling and the experimental results is found, in particular concerning the SBS activity in the plasma and the backscatter level. The results underline the importance of nonlocal transport effects affecting the onset of self-focusing for temperatures below 1keV. The simulations with the monospeckle beam allow to identify the resonant filament instability [1] and the subsequent loss of coherence of the laser beam as the reason of the observed low-level backscatter levels measured in the experiments. To achieve reliable numerical modeling, a good characterisation of the plasma profiles and the timing with respect to the laser pulse shape, prior to simulations, proves to be extremely important.

  3. Modeling of stimulated Brillouin scattering in expanding plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hueller, S; Masson-Laborde, P E; Pesme, D [Centre de Physique Theorique, CNRS UMR7644, ecole Polytechnique, Palaiseau (France); Labaune, C; Bandulet, H [LULI, CNRS UMR7605, ecole Polytechnique, Palaiseau (France)], E-mail: hueller@cpht.polytechnique.fr

    2008-05-15

    Numerical simulations of mm-size expanding plasmas have been performed in comparison with recent experiments at the LULI facility. The features of Stimulated Brillouin Scattering (SBS) are studied for an intense mono-speckle laser beam in continuation of previous work on optically smoothed laser beams. Very good agreement between the theoretical-numerical modeling and the experimental results is found, in particular concerning the SBS activity in the plasma and the backscatter level. The results underline the importance of nonlocal transport effects affecting the onset of self-focusing for temperatures below 1keV. The simulations with the monospeckle beam allow to identify the resonant filament instability and the subsequent loss of coherence of the laser beam as the reason of the observed low-level backscatter levels measured in the experiments. To achieve reliable numerical modeling, a good characterisation of the plasma profiles and the timing with respect to the laser pulse shape, prior to simulations, proves to be extremely important.

  4. A simple model of suppressing stimulated Brillouin scattering in optical fiber with frequency-modulated laser

    International Nuclear Information System (INIS)

    A simple model is developed to study the mechanism of stimulated Brillouin scattering (SBS) suppression with frequency-modulated laser in optical fiber. By taking into account the laser frequency distribution along the fiber induced by frequency modulation, the average effective Brillouin gain is calculated to determine the SBS threshold. Experimental results show agreement with the numerical analysis. The application for SBS suppression in interferometric fiber sensing system is also discussed in this paper. The results show that the maximum input power can be increased effectively by frequency modulation method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  5. Stimulated Brillouin scattering during electron gyro-harmonic heating at EISCAT

    OpenAIRE

    Fu, H. Y.; Scales, W. A.; Bernhardt, P. A.; S. J. Briczinski; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.; J. M. Ruohoniemi

    2015-01-01

    Published version. Source at http://doi.org/10.5194/angeo-33-983-2015. Observations of secondary radiation, stimulated electromagnetic emission (SEE), produced during ionospheric modification experiments using ground-based, high-power, high-frequency (HF) radio waves are considered. The High Frequency Active Auroral Research Program (HAARP) facility is capable of generating narrowband SEE in the form of stimulated Brillouin scatter (SBS) and stimulated ion Bernstein scatter (SIBS) in the S...

  6. Wide-range wavevector selectivity of magnon gases in Brillouin light scattering spectroscopy

    OpenAIRE

    Sandweg, C. W.; Jungfleisch, M. B.; Vasyuchka, V I; Serga, A. A.; Clausen, P.; Schultheiss, H.; Hillebrands, B.; Kreisel, A.(University of Colorado, 80309, Boulder, Colorado, USA); Kopietz, P.

    2010-01-01

    Brillouin light scattering spectroscopy is a powerful technique for the study of fast magnetization dynamics with both frequency- and wavevector resolution. Here, we report on a distinct improvement of this spectroscopic technique towards two-dimensional wide-range wavevector selectivity in a backward scattering geometry. Spin-wave wavevectors oriented perpendicular to the bias magnetic field are investigated by tilting the sample within the magnet gap. Wavevectors which are oriented parallel...

  7. Stimulated Brillouin scattering during electron gyro-harmonic heating at EISCAT

    Science.gov (United States)

    Fu, H. Y.; Scales, W. A.; Bernhardt, P. A.; Briczinski, S. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.; Ruohoniemi, J. M.

    2015-08-01

    Observations of secondary radiation, stimulated electromagnetic emission (SEE), produced during ionospheric modification experiments using ground-based, high-power, high-frequency (HF) radio waves are considered. The High Frequency Active Auroral Research Program (HAARP) facility is capable of generating narrowband SEE in the form of stimulated Brillouin scatter (SBS) and stimulated ion Bernstein scatter (SIBS) in the SEE spectrum. Such narrowband SEE spectral lines have not been reported using the European Incoherent Scatter (EISCAT) heater facility before. This work reports the first EISCAT results of narrowband SEE spectra and compares them to SEE previously observed at HAARP during electron gyro-harmonic heating. An analysis of experimental SEE data shows observations of emission lines within 100 Hz of the pump frequency, interpreted as SBS, during the 2012 July EISCAT campaign. Experimental results indicate that SBS strengthens as the pump frequency approaches the third electron gyro-harmonic. Also, for different heater antenna beam angles, the CUTLASS radar backscatter induced by HF radio pumping is suppressed near electron gyro-harmonics, whereas electron temperature enhancement weakens as measured by EISCAT/UHF radar. The main features of these new narrowband EISCAT observations are generally consistent with previous SBS measurements at HAARP.

  8. Metamaterial control of stimulated Brillouin scattering

    CERN Document Server

    Smith, M J A; de Sterke, C Martijn; Wolff, C; Lapine, M; Poulton, C G

    2016-01-01

    Using full opto-acoustic numerical simulations, we demonstrate enhancement and suppression of the SBS gain coefficient in a metamaterial comprising a subwavelength cubic array of dielectric spheres suspended in a dielectric background material. We develop a general theoretical framework and present several numerical examples for technologically important material combinations. For As$_2$S$_3$ spheres suspended in silicon, we achieve an enhancement of more than one order of magnitude in the SBS gain coefficient compared to pure silicon, and for GaAs spheres in silicon, perfect suppression of SBS is obtained. The gain coefficient for As$_2$S$_3$ glass can also be strongly suppressed by introducing a suspension of amorphous silica spheres. Effective photonic and acoustic parameters are shown to depend in a complex way on the filling fraction, and each have varying influence on the effective gain coefficient of the metamaterial. For the studied combinations of materials, electrostriction is the dominant effect be...

  9. An ultrawide tunable range single passband microwave photonic filter based on stimulated Brillouin scattering.

    Science.gov (United States)

    Xiao, Yongchuan; Guo, Jing; Wu, Kui; Qu, Pengfei; Qi, Huajuan; Liu, Caixia; Ruan, Shengping; Chen, Weiyou; Dong, Wei

    2013-02-11

    A single passband microwave photonic filter with ultrawide tunable range based on stimulated Brillouin scattering is theoretically analyzed. Combining the gain and loss spectrums, tuning range with 44GHz is obtained without crosstalk by introducing two pumps. Adding more pumps, Tuning range multiplying with the multiplication factor equaling to the total quantity of pump can be achieved, which has potential application in microwave and millimeter wave wireless communication systems.

  10. Tunable narrowband microwave photonic filter created by stimulated Brillouin scattering from a silicon nanowire

    Science.gov (United States)

    Casas-Bedoya, Alvaro; Morrison, Blair; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J.

    2015-09-01

    We demonstrate the first functional signal processing device based on stimulated Brillouin scattering in a silicon nanowire. We use only 1 dB of on-chip SBS gain to create an RF photonic notch filter with 48 dB of suppression, 98 MHz linewidth, and 6 GHz frequency tuning. This device has potential applications in on-chip microwave signal processing and establishes the foundation for the first CMOS-compatible high performance RF photonic filter.

  11. An ultrawide tunable range single passband microwave photonic filter based on stimulated Brillouin scattering.

    Science.gov (United States)

    Xiao, Yongchuan; Guo, Jing; Wu, Kui; Qu, Pengfei; Qi, Huajuan; Liu, Caixia; Ruan, Shengping; Chen, Weiyou; Dong, Wei

    2013-02-11

    A single passband microwave photonic filter with ultrawide tunable range based on stimulated Brillouin scattering is theoretically analyzed. Combining the gain and loss spectrums, tuning range with 44GHz is obtained without crosstalk by introducing two pumps. Adding more pumps, Tuning range multiplying with the multiplication factor equaling to the total quantity of pump can be achieved, which has potential application in microwave and millimeter wave wireless communication systems. PMID:23481728

  12. Tunable narrowband microwave photonic filter created by stimulated Brillouin scattering from a Silicon nanowire

    CERN Document Server

    Casas-Bedoya, Alvaro; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J

    2015-01-01

    We demonstrate the first functional signal processing device based on stimulated Brillouin scattering in a silicon nanowire. We use only 1 dB of on-chip SBS gain to create an RF photonic notch filter with 48 dB of suppression, 98 MHz linewidth, and 6 GHz frequency tuning. This device has potential applications in on-chip microwave signal processing and establishes the foundation for the first CMOS-compatible high performance RF photonic filter.

  13. Amplification of stimulated Brillouin scattering of two collinear pulsed laser beams with orthogonal polarizations.

    Science.gov (United States)

    Shi, Jinwei; Chen, Xudong; Ouyang, Min; Liu, Juan; Liu, Dahe

    2009-06-10

    A polarization-controlling device was developed based on the fact that there can be a time delay between the seeder and the pumping beams during the amplification of a stimulated Brillouin scattering signal. The device causes two coaxially transmitted pulsed beams with orthogonal polarizations to have the same polarization in order to implement amplification by the pumping effect. An experiment showed that good pumping amplification can be achieved by using this technique. PMID:19516374

  14. Brillouin scattering study of the ferroelectric phase transition in tris-sarcosine calcium chloride

    Science.gov (United States)

    Hikita, Tomoyuki; Schnackenberg, Paul; Schmidt, V. Hugo

    1985-01-01

    Brillouin spectra from longitudinal phonons in ferroelectric tris-sarcosine calcium chloride propagating along [100], [010], and [001] have been measured as functions of temperature. Large anomalies were found in the Brillouin shift and linewidth in the [100] and [001] phonons. These anomalies are interpreted as arising from the linear coupling of the polarization and the phonons. From the temperature where the linewidth is maximum, the relaxation time of the polarization fluctuations is estimated to be τ=3.1×10-12/(Tc-T) sec, where Tc is the ferroelectric transition temperature. We also observed anomalies in Brillouin shift and linewidth of the [010] phonons which propagate along the ferroelectric b axis. These anomalies are interpreted as coming from electro- strictive coupling. The energy-relaxation time was estimated to be τE=2.5×10-10/(T-Tc) sec in the paraelectric phase and τE=1.0×10-9/(Tc-T) sec in the ferroelectric phase, by comparing our Brillouin results with those of the ultrasonic measurements.

  15. Direct detection of magnetostatic wave excitations in magnetostatic wave device structures by Brillouin light scattering

    Science.gov (United States)

    Srinivasan, G.; Patton, C. E.

    1985-10-01

    The technique of Brillouin light scattering has been used to detect magnetostatic wave (MSW) excitations in MSW microwave device structures. The present results are for a signal-to-noise enhancer consisting of a microstrip transmission line in contact with a yttrium iron garnet film with the applied magnetic field parallel to the microstrip line. At low input microwave power levels, the MSW spectra at 4 GHz consisted of surface excitations with wave numbers from about 80 to 470/cm, with the propagation direction perpendicular to the microstrip line. At high power levels, parametric half-frequency MSW excitations were observed, accompanied by a decrease in the scattering of the surface MSW excitations at the pump frequency.

  16. Brillouin light scattering study of Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al and Co{sub 2}FeAl Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gaier, O; Hamrle, J; Trudel, S; Conca Parra, A; Hillebrands, B [Fachbereich Physik and Forschungszentrum OPTIMAS, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 56, D-67663 Kaiserslautern (Germany); Arbelo, E; Herbort, C; Jourdan, M, E-mail: gaier@physik.uni-kl.d [Institut fuer Physik, Johannes-Gutenberg-Universitaet Mainz, Staudinger Weg 7, D-55099 Mainz (Germany)

    2009-04-21

    The thermal magnonic spectra of Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al (CCFA) and Co{sub 2}FeAl were investigated using Brillouin light scattering (BLS) spectroscopy. For CCFA, the exchange constant A (exchange stiffness D) is found to be 0.48 {+-} 0.04 {mu}erg cm{sup -1} (203 {+-} 16 meV A{sup 2}), while for Co{sub 2}FeAl the corresponding values of 1.55 {+-} 0.05 {mu}erg cm{sup -1} (370 {+-} 10 meV A{sup 2}) were found. The observed asymmetry in the BLS spectra between the Stokes and anti-Stokes frequencies was assigned to an interplay between the asymmetrical profiles of hybridized Damon-Esbach and perpendicular standing spin-wave modes, combined with the optical sensitivity of the BLS signal to the upper side of the CCFA or Co{sub 2}FeAl film.

  17. Stimulated Brillouin scattering of an electromagnetic wave in weakly magnetized plasma with variably charged dust particles

    Indian Academy of Sciences (India)

    Sourabh Bal; M Bose

    2009-10-01

    We have investigated analytically the stimulated Brillouin scattering (SBS) of an electromagnetic wave in non-dissipative weakly magnetized plasma in the presence of dust particles with variable charge.

  18. Development of low-temperature and high-pressure Brillouin scattering spectroscopy and its application to the solid I form of hydrogen sulphide

    CERN Document Server

    Murase, S; Sasaki, S; Kume, T; Shimizu, H

    2002-01-01

    A new experimental system has been developed for low-temperature and high-pressure Brillouin scattering measurements. The new system allows us to investigate the elastic properties of samples in a diamond anvil cell (DAC) down to liquid N sub 2 temperature (approx 80 K). In contrast to the case in our conventional technique, the optics in the system can be rotated for measuring the direction dependence of acoustic velocities of the samples in the DAC fixed in the cryostat. The new experimental technique was applied to the solid I form of hydrogen sulphide (H sub 2 S). As a result, three ratios of elastic constants to density were successfully determined at P = 3.70 GPa, T = 240 K: C sub 1 sub 1 /rho = 16.4, C sub 1 sub 2 /rho = 12.4, C sub 4 sub 4 /rho = 7.57 x 10 sup 6 m sup 2 s sup - sup 2. These values are almost the same as those obtained at room temperature.

  19. Current trends in laser fusion driver and beam combination laser systems using stimulated Brillouin scattering phase conjugate mirrors for a fusion driver

    International Nuclear Information System (INIS)

    Laser facilities in the world have been developing flash-lamp-pumped ultrahigh-energy solid-state lasers for fusion research and high-repetition diode-pumped solid-state lasers to act as commercial fusion drivers. A commercial laser fusion driver requires a high-energy beam with a total energy of several megajoules per pulse in several nanoseconds with a ∼10-Hz repetition rate. However, current laser technologies have limitations in raising the beam energy when operating with a high repetition rate, which is necessary for a commercial fusion driver to function properly. The beam combination laser system, which that uses stimulated Brillouin scattering phase conjugate mirrors, is a promising candidate for a fusion driver because it can obtain both a high energy and a high repetition rate with separate amplifications. For the realization of the beam combination laser system, a self-phase control technique was proposed for the coherent beam combined output, and its principle was demonstrated experimentally.

  20. Experimental investigation of the stimulated Brillouin scattering growth and saturation at 526 and 351 nm for direct drive and shock ignition

    Energy Technology Data Exchange (ETDEWEB)

    Depierreux, S.; Loiseau, P.; Tassin, V.; Masson-Laborde, P.-E.; Goyon, C. [CEA DAM DIF, F-91297 Arpajon (France); Michel, D. T.; Yahia, V. [CEA DAM DIF, F-91297 Arpajon (France); LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Stenz, C. [CELIA, Universite Bordeaux 1, 351 cours de la Liberation, 33405 Talence cedex (France); Labaune, C. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France)

    2012-01-15

    We have designed experiments to study the effect of the laser wavelength (0.527 versus 0.351 {mu}m) on the coupling efficiency in plasma conditions relevant to compression and shock ignition (SI) schemes in different intensity regimes. A difficult issue was to produce interaction conditions that are equivalent for the two wavelengths. This was obtained by using plasma preformed from a solid target with a plasma-preforming beam at the same wavelength as the interaction beam. This produced an almost exponential density profile from vacuum to the critical density of the interaction beam in which all interaction mechanisms are taken into account. The growth and saturation of stimulated Brillouin scattering (SBS) have been measured at the two wavelengths, in backward as well as in near-backward directions. We have found that the SBS intensity threshold is {approx}1.5 times higher at 3{omega} than at 2{omega} in agreement with the I{lambda} dependence of the SBS gain. The SBS behaviour is very well reproduced by the linear calculations of the postprocessor PIRANAH, giving us confidence that we have a good control of the relevance of the experimental conditions for the study of the laser wavelength effect on laser-plasma coupling. When SBS reaches the saturation regime, same levels of reflectivity are measured at 2 and 3{omega}. Numerical simulations were performed with the paraxial code HERA to study the contribution of the fluid mechanisms in the saturation of SBS, showing that pump depletion and interplay with filamentation are likely to be the most important processes in SBS saturation for these conditions. This scenario also applies to the SBS of shock ignition high-intensity beams.

  1. Investigation of stimulated Brillouin scattering for broadband KrF laser

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Hui; Lǘ Zhi-Wei; Lin Dian-Yang; Wang Chao; Zhao Xiao-Yan; Tang Xiu-Zhang; Zhang Hai-Feng; Shan Yu-Sheng

    2004-01-01

    Stimulated Brillouin scattering (SBS) numerical mode for broadband multimode KrF laser pump with optical breakdown has been built up in this paper. The basic premises of the model are that KrF spectrum is composed of a number of lines and SBS arises from these lines with coupling to some extent. The broadband SBS threshold strongly depends on pump bandwidth. SBS and optical breakdown occur nearly simultaneously when broadband SBS and breakdown have the same threshold. The decrease of saturation reflectivity for broadband pump radiation is explained with this model. Experimental results agree well with the model.

  2. Stimulated Brillouin Scattering Damage of Large-Aperture Fused Silica Grating

    Institute of Scientific and Technical Information of China (English)

    HAN Wei; ZHENG Wan-Guo; HUANG Wan-Qing; LI Ke-Yu; WANG Fang; FENG Bin; JIA Huai-Ting; LI Fu-Quan; XIANG Yong; JING Feng

    2010-01-01

    @@ Laser induced damage experiment fs carried out on a large aperture laser facility.Severe damage is observed on a large-aperture fused silica grating which presents dense craters on the front surface and six cracks alternatively located at the front and the rear surface.The bizarre fact about the damage on the grating is that,unlike other optics,the damage craters are almost on the front surface.According to observation,damage phenomenon is due to the stimulated Brillouin scattering(SBS)effect occurring in the grating,which includes the transverse SBS,the back SBS and the zigzag SBS.

  3. Direct observation of the saturation of stimulated Brillouin scattering by ion-trapping induced frequency shifts

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, C; Price, D; Meezan, N; Gregori, G; Divol, L; Froula, D H; Glenzer, S H; Offenberger, A A; Ao, T; Smith, C A

    2004-02-25

    We report the first measurement of the saturation of stimulated Brillouin scattering (SBS) by an ion-trapping induced frequency shift, which was achieved by directly measuring the amplitude and absolute frequency of SBS-driven ion-acoustic waves (IAW). A frequency shift of up to 30% and a simultaneous saturation of driven IAW and SBS reflectivity was observed. The scaling of the frequency shift with the IAW amplitude compares well with theoretical calculations. We have further measured fast 30 ps oscillations of the SBS-driven IAW amplitude induced by the frequency shift.

  4. Dual-band bandpass tunable microwave photonic filter based on stimulated Brillouin scattering

    Science.gov (United States)

    Li, Jia-qi; Xiao, Yong-chuan; Dong, Wei; Zhang, Xin-dong

    2016-07-01

    A dual-band bandpass microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is theoretically analyzed and experimentally demonstrated. Two separated tunable laser sources (TLSs) are employed to generate two passbands by implementing phase modulation to amplitude modulation conversion by using SBS induced sideband amplification. The center frequencies of both passbands can be independently tuned ranging from 1 GHz to 19 GHz. High resolution with 3 dB bandwidth less than 30 MHz and large out-of-band rejection about 40 dB under 25 mW optical pump power are achieved.

  5. Tunable microwave notch filter created by stimulated Brillouin scattering in a silicon chip

    Science.gov (United States)

    Casas-Bedoya, A.; Morrison, Blair; Pagani, Mattia; Marpaung, David; Eggleton, Benjamin J.

    2015-12-01

    We show the first functional signal processing device based on forward stimulated Brillouin scattering from a silicon nanowire. We harness 1dB of SBS gain to create a high performance, energy efficient microwave photonic notch filter. The filter possess 48dB of suppression, 98 MHz linewidth, and is tunable within a 6 GHz bandwidth. This demonstration represents a significant advance in integrated microwave photonics with potential applications in on-chip microwave signal processing and establish the foundation towards the first CMOS-compatible high performance RF photonic filter.

  6. Triple-resonant Brillouin light scattering in magneto-optical cavities

    CERN Document Server

    Haigh, J A; Ramsay, A J; Ferguson, A J

    2016-01-01

    An enhancement in Brillouin light scattering of optical photons with magnons is demonstrated in magneto-optical whispering gallery mode resonators tuned to a triple resonance point. This occurs when both the input and output optical modes are resonant with those of the whispering gallery resonator, with a separation given by the ferromagnetic resonance (FMR) frequency. The identification and excitation of specific optical modes allows us to gain a clear understanding of the mode-matching conditions. A selection rule due to wavevector matching leads to an intrinsic single-sideband excitation. Strong suppression of one sideband is essential for one-to-one frequency mapping in coherent optical-to-microwave conversion.

  7. Elastic properties of boron carbide films via surface acoustic waves measured by Brillouin light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Salas, E.; Jimenez-Villacorta, F.; Jimenez Rioboo, R.J.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Sanchez-Marcos, J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Munoz-Martin, A.; Prieto, J.E.; Joco, V. [Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2013-03-15

    Surface acoustic wave (SAW) velocity has been determined by high resolution Brillouin light scattering to study the mechano-elastic properties of boron carbide films prepared by radio frequency (RF) sputtering. The comparison of experimentally observed elastic behaviour with simulations made by considering film composition obtained from elastic recoil detection analysis-time of flight (ERDA-ToF) spectroscopy allows establishing that elastic properties are determined by that of crystalline boron carbide with a lessening of the SAW velocity values due to surface oxidation. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Spectroscopic properties of KGd(WO 4) 2: (Er, Yb) single crystals studied by Brillouin scattering method

    Science.gov (United States)

    Kasprowicz, D.; Drozdowski, M.; Majchrowski, A.; Michalski, E.

    2007-09-01

    The study of KGW: (Er, Yb) was performed for the acoustic phonons [1 0 0], [0 0 1], [-1 0 1], [1 0 1], [1 1 0] and [0 1 1]. In some Brillouin spectra obtained at room temperature we observed additional modes connected with mixed polarization modes propagating as quasi-longitudinal or quasi-transverse phonons which is characteristic for low symmetry crystals. Moreover, it has been revealed, that the value of Brillouin shift and integral intensity of the longitudinal phonon [1 0 1] propagating in KGW: (Er, Yb) show the anomaly at about 175 K.

  9. Spectrum parameter estimation in Brillouin scattering distributed temperature sensor based on cuckoo search algorithm combined with the improved differential evolution algorithm

    Science.gov (United States)

    Zhang, Yanjun; Yu, Chunjuan; Fu, Xinghu; Liu, Wenzhe; Bi, Weihong

    2015-12-01

    In the distributed optical fiber sensing system based on Brillouin scattering, strain and temperature are the main measuring parameters which can be obtained by analyzing the Brillouin center frequency shift. The novel algorithm which combines the cuckoo search algorithm (CS) with the improved differential evolution (IDE) algorithm is proposed for the Brillouin scattering parameter estimation. The CS-IDE algorithm is compared with CS algorithm and analyzed in different situation. The results show that both the CS and CS-IDE algorithm have very good convergence. The analysis reveals that the CS-IDE algorithm can extract the scattering spectrum features with different linear weight ratio, linewidth combination and SNR. Moreover, the BOTDR temperature measuring system based on electron optical frequency shift is set up to verify the effectiveness of the CS-IDE algorithm. Experimental results show that there is a good linear relationship between the Brillouin center frequency shift and temperature changes.

  10. Multi-parameter sensor based on stimulated Brillouin scattering in inverse-parabolic graded-index fiber.

    Science.gov (United States)

    Xu, Yanping; Ren, Meiqi; Lu, Yang; Lu, Ping; Lu, Ping; Bao, Xiaoyi; Wang, Lixian; Messaddeq, Younès; LaRochelle, Sophie

    2016-03-15

    We propose a unique multi-parameter optical fiber sensor based on intramodal stimulated Brillouin scattering of higher-order acoustic modes in inverse-parabolic graded-index fiber (IPGIF) without a mode converter. Both optical modes and acoustic modes guided in the IPGIF are characterized and demonstrated theoretically and experimentally. Simulation analysis shows that the multi-peak feature in the Brillouin gain spectrum of the IPGIF is attributed to the couplings between the guided optical mode and the higher-order acoustic modes. Thanks to the distinct acoustic properties of the peaks induced by the sharp refractive index profile of the IPGIF, the different temperature and strain dependences of the first three Brillouin peaks enable the discrimination of the temperature and strain at an accuracy of 0.85°C and 17.4 με. PMID:26977653

  11. Multi-parameter sensor based on stimulated Brillouin scattering in inverse-parabolic graded-index fiber.

    Science.gov (United States)

    Xu, Yanping; Ren, Meiqi; Lu, Yang; Lu, Ping; Lu, Ping; Bao, Xiaoyi; Wang, Lixian; Messaddeq, Younès; LaRochelle, Sophie

    2016-03-15

    We propose a unique multi-parameter optical fiber sensor based on intramodal stimulated Brillouin scattering of higher-order acoustic modes in inverse-parabolic graded-index fiber (IPGIF) without a mode converter. Both optical modes and acoustic modes guided in the IPGIF are characterized and demonstrated theoretically and experimentally. Simulation analysis shows that the multi-peak feature in the Brillouin gain spectrum of the IPGIF is attributed to the couplings between the guided optical mode and the higher-order acoustic modes. Thanks to the distinct acoustic properties of the peaks induced by the sharp refractive index profile of the IPGIF, the different temperature and strain dependences of the first three Brillouin peaks enable the discrimination of the temperature and strain at an accuracy of 0.85°C and 17.4 με.

  12. Numerical study of all-optical slow-light delays via stimulated Brillouin scattering in an optical fiber

    Science.gov (United States)

    Zhu, Zhaoming; Gauthier, Daniel J.; Okawachi, Yoshitomo; Sharping, Jay E.; Gaeta, Alexander L.; Boyd, Robert W.; Willner, Alan E.

    2005-11-01

    We study numerically all-optical slow-light delays in room-temperature single-mode optical fibers induced by stimulated Brillouin scattering. We consider the propagation of a pulse through a cw-pumped Brillouin fiber amplifier, where the carrier frequency of the pulse is tuned near the Stokes resonance. Pulse delay and broadening of the Stokes pulse are studied in the small-signal and gain-saturation regimes. Pulse delay is shown to be limited by saturation of the Brillouin amplifier. In the small-signal regime, both time delay and pulse broadening increase with increasing gain. In the gain-saturation regime, both time delay and broadening decrease with increasing gain, and the pulse even achieves advancement. Time delay of more than one pulse-width is observed with modest pulse distortion, and over one pulse-width advancement can be obtained with larger pulse distortion in the gain-saturation regime.

  13. Design of small core tellurite photonic crystal fiber for slow-light-based application using stimulated Brillouin scattering

    Science.gov (United States)

    Cherif, Rim; Salem, Amine Ben; Saini, Than Singh; Kumar, Ajeet; Sinha, Ravindra K.; Zghal, Mourad

    2015-07-01

    Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crystal fibers (PCF) are rigorously studied. We propose a design of tellurite PCF that is used for slow-light-based applications. We developed a two-dimensional finite element mode solver to numerically study the acoustic and optical properties of complex refractive index profiles including tellurite PCF. Our results include the calculation of Brillouin gain spectrum, Brillouin gain coefficient (gB) and Brillouin frequency shift by taking into account the contribution of the higher-order acoustic modes. Several simulations were run by varying the air-filling ratio of various PCF structures to enhance the SBS. The real scanning electron microscope image of a small core of highly nonlinear tellurite fiber is considered. Optimized results show a frequency shift of 8.43 GHz and a Brillouin gain of 9.48×10-11 m/W with a time delay between 21 and 140 ns. Such fibers have drawn much interest because of their capacity for increasing and tailoring the SBS gain.

  14. Attometer resolution spectral analysis based on polarization pulling assisted Brillouin scattering merged with heterodyne detection.

    Science.gov (United States)

    Preussler, Stefan; Schneider, Thomas

    2015-10-01

    Spectral analysis is essential for measuring and monitoring advanced optical communication systems and the characterization of active and passive devices like amplifiers, filters and especially frequency combs. Conventional devices have a limited resolution or tuning range. Therefore, the true spectral shape of the signal remains hidden. In this work, a small part of the signal under test is preselected with help of the polarization pulling effect of stimulated Brillouin scattering where all unwanted spectral components are suppressed. Subsequently, this part is analyzed more deeply through heterodyne detection. Thereby, the local oscillator is generated from a narrow linewidth fiber laser which acts also as pump wave for Brillouin scattering. By scanning the pump wave together with the local oscillator through the signal spectrum, the whole signal is measured. The method is tunable over a broad wavelength range, is not affected by unwanted mixing products and utilizes a conventional narrow bandwidth photo diode. First proof of concept experiments show the measurement of the power spectral density function with a resolution in the attometer or lower kilohertz range at 1550 nm. PMID:26480198

  15. Single laser pulse compression via strongly coupled stimulated Brillouin scattering in plasma

    Science.gov (United States)

    Peng, H.; Wu, Z. H.; Zuo, Y. L.; Zhang, Z. M.; Zhou, K. N.; Su, J. Q.

    2016-07-01

    Laser amplification in plasma, including stimulated Raman scattering amplification and strongly coupled stimulated Brillouin scattering (sc-SBS) amplification, is very promising to generate ultrahigh-power and ultrashort laser pulses. But both are quite complex in experiments: at least three different laser pulses must be prepared; temporal delay and spatial overlap of these three pulses are difficult. We propose a single pulse compression scheme based on sc-SBS in plasma. Only one moderately long laser is applied, the front part of which ionizes the gas to produced plasma, and gets reflected by a plasma mirror at the end of the gas channel. The reflected front quickly depletes the remaining part of the laser by sc-SBS in the self-similar regime. The output laser is much stronger and shorter. This scheme is at first considered theoretically, then validated by using 1D PIC simulations.

  16. High-extinction VIPA-based Brillouin spectroscopy of turbid biological media

    CERN Document Server

    Fiore, Antonio; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

    2016-01-01

    Brillouin microscopy has recently emerged as powerful technique to characterize the mechanical properties of biological tissue, cell and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we developed a spectrometer composed of a two VIPA stages and a multi-pass Fabry-Perot interferometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 microns deep within chicken muscle tissue.

  17. High-extinction virtually imaged phased array-based Brillouin spectroscopy of turbid biological media

    Science.gov (United States)

    Fiore, Antonio; Zhang, Jitao; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

    2016-05-01

    Brillouin microscopy has recently emerged as a powerful technique to characterize the mechanical properties of biological tissue, cell, and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we combined a multi-pass Fabry-Perot interferometer with a two-stage virtually imaged phased array spectrometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 μm deep within chicken muscle tissue.

  18. 16-Moment Approximation for Ion Velocity Distribution and its Application in Calculations of Incoherent Scatter Spectra

    Institute of Scientific and Technical Information of China (English)

    XUE Kun; GUO Lixin; WV Jian; XU Bin; FANG Chaofeng

    2009-01-01

    A sixteen moment approximation based on a bi-Maxwellian that contains the stress tensor and the heat flow vector is applied to describe the ion velocity distribution which influences the incoherent scatter spectra. A discussion is made about the effects on the incoherent scatter spectra caused by different values of the normalized perpendicular drift velocity D, aspect angle φ between the magnetic field and the line-of-sight direction, and the ratio α of the ion-neutral collision to ion cyclotron frequency. Numerical results show that the shifting and asymmetry of incoherent scatter spectra appear parallel to E × B and E as the normalized perpendicular drift velocity D increases due to the ion drift velocity, the stress tensor and the heat flow vector respectively. However, the spectrum is always typically double-humped Maxwellian parallel to B. The ion velocity distribution is more distorted from the Maxwellian as the aspect angle φ increases from 0° to 90°, and consequently the incoherent scatter spectra is no longer typically double-humped Maxwellian. As α increases, the ion velocity distribution becomes Maxwellian and the incoherent scatter spectra become typically double-humped Maxwellian even with a large value of the normalized perpendicular drift velocity D. It is reasonable to use the sixteen-moment approximation to describe the non-Maxwellian plasma characterized by the large temperature anisotropy.

  19. Study on two-cell stimulated Brillouin scattering system with mixture medium

    Institute of Scientific and Technical Information of China (English)

    HASI Wuliji; L(U) ZhiWei; LI Qiang; BA DeXin; HE WeiMing

    2007-01-01

    In this paper, a method of choosing mixture medium in two-cell stimulated Brillouin scattering (SBS) system to improve the system performance is proposed. The Brillouin frequency shift (BFS) of mixture medium varies with the mixing ratio and thus the difference of the BFS between the two cells can be eliminated. The two-cell SBS system with acetone (C3H6O) in its generator cell and mixture liquid of CCl4/C2Cl4 in its amplifier cell is investigated. The C3H6O has a high optical break- down threshold and the mixture liquid of CCl4/C2Cl4 has a small absorption coefficient and the same BFS as that of C3H6O when the volume fraction of CCl4 is 4%. Compared with two-cell SBS system with the same liquid (C2Cl4) or different liquid (C3H6O and C2Cl4) in generator and amplifier cell, the SBS system with mixture liquid (CCl4/C2Cl4) in amplifier cell and C3H6O in generator cell improves the power-load, energy reflectivity (ER), phase conjugation (PC) fidelity and ER stability.

  20. Picosecond ultrasonics in single cells: Interface step motion for thin animal cells and Brillouin scattering for thick vegetal cells

    Science.gov (United States)

    Ducousso, M.; Dehoux, T.; Audoin, B.; Zouani, O.; Chollet, C.; Durrieu, M. C.

    2011-01-01

    The measurement of the mechanical properties of single biological cells using a picosecond laser-ultrasonic method is proposed. A pump-probe set-up based on ultrafast laser (100 fs pulses) is used to generate and detect acoustic frequencies in the GHz range in a cell on a metallic substrate. The time resolution is about 1 ps and the laser focusing allows a 1 μm lateral resolution. We carry out experiments in both animal and vegetal cells. A semi-analytical simulation model of the physical phenomena involved in experiments is presented. The coupled heat and stress equations are solved including a thermal boundary resistance at the cell/substrate interface and strong acoustic absorption. The optical detection resulting from the interaction between the acoustic wave and the laser light is also modelled. Simulations allow the analysis of experimental signals in both vegetal and animal cells. The results support the potentialities of the non-invasive technique for bioengineering and medical applications.

  1. Nondestructive Inspection by Using Scattering and Spectra in Terahertz Waves

    Science.gov (United States)

    Shibuya, Takayuki; Yamashita, Masahiro; Ogawa, Yuichi; Otani, Chiko; Kawase, Kodo; Inoue, Hiroyuki; Kanamori, Tatsuyuki

    In this paper, we show that the nondestructive detection of chemicals hidden in envelopes can be achieved using terahertz waves in a simple two-step procedure: First, scattering of the terahertz waves is an indicator of the presence of powders in the envelope; second, the identification of the chemicals is done by spectral fingerprinting. In addition, we examined the possibility of measurement by diffuse reflection.

  2. Bandwidth-tunable narrowband rectangular optical filter based on stimulated Brillouin scattering in optical fiber.

    Science.gov (United States)

    Wei, Wei; Yi, Lilin; Jaouën, Yves; Hu, Weisheng

    2014-09-22

    We propose a rectangular optical filter based on stimulated Brillouin scattering (SBS) in optical fiber with bandwidth tuning from 50 MHz to 4 GHz at less than 15-MHz resolution. The rectangular shape of the filter is precisely achieved utilizing digital feedback control of the comb-like pump spectral lines. The passband ripple is suppressed to ~1 dB by mitigating the nonlinearity influences of the comb-like pump lines generated in electrical and optical components and fibers. Moreover a fiber with a single Brillouin peak is employed to further reduce the in-band ripple and the out-of-band SBS gain at the same time. Finally, we analyze the noise performance of the filter at different bandwidth cases and demonstrate the system performance of the proposed filter with 2.1-GHz bandwidth and 19-dB gain by amplifying a 2-GHz orthogonal frequency-division-multiplexing (OFDM) signal with quadrature-phase-shift-keying (QPSK) and 16-quadrature-amplitude-modulation (16-QAM) on each subscriber.

  3. Second-order Scattering and Frequency Doubling Scattering Spectra of Thallium(III)-Methotrexate System and Its Analytical Application

    Institute of Scientific and Technical Information of China (English)

    XI Cun-Xian; LIU Zhong-Fang; HU Xiao-Li; LIU Shao-Pu; DUAN Hui

    2008-01-01

    In pH 4.9 Britton-Robinson buffer solution,methotrexate (MTX) reacted with thallium(III) to form a 3:1 che late.This resulted in great enhancement of second-order scattering (SOS) spectra and frequency doubling scattering (FDS) spectra and appearance of new SOS and FDS spectra.Their maximum wavelengths were located at 520 and 390 nm,respectively.The increments of scattering intensities (ΔI) were directly proportional to the concentrations of MTX in the ranges of 0.022--2.0 μg·mL-1 (SOS method) and 0.008--2.5μg·mL-1 (FDS method).The methods exhibited high sensitivities.The detection limits for MTX were 7.4 ng·mL-1 (SOS method) and 2.3 ng.mL-1 (FDS method),respectively.The optimum conditions of the reaction,the influencing factors and the effects of coexisting substances were investigated.A highly sensitive,simple and fast method for the determination of MTX has been developed.The method can be applied satisfactorily to the determination of MTX in human serum samples.In this work,the charge distribution of MTX was calculated by a CNDO quantum chemistry method.In addition,the reaction mechanism was discussed.

  4. Method for pulse control in a laser including a stimulated brillouin scattering mirror system

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-10-23

    A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

  5. Highly precise distributed Brillouin scattering sensor for structural health monitoring of optical ground wire cable

    Science.gov (United States)

    Zou, Lufan; Ravet, Fabien; Bao, Xiaoyi; Chen, Liang

    2004-07-01

    A distributed Brillouin scattering sensor with high special precision has been developed for the measurement of small damages/cracks of 1.5 cm. The out-layer damaged regions in an optical ground wire (OPGW) cable have been identified successfully by measuring the strain distributions every 5 cm using this technology. The stress increased to 127 kN which corresponds to more than 7500 micro-strain in the fibers. The locations of structural indentations comprising repaired and undamaged regions are found and distinguished using their corresponding strain data. The elongation of repaired region increases with time on 127 kN. These results are quantified in terms of the fiber orientation, stress, and behavior relative to undamaged sections.

  6. Brillouin Light Scattering study of patterned TiN/SiOC:H/Si structures

    Science.gov (United States)

    Zizka, Jonathan; King, Sean; Antonelli, Andy; Sooryakumar, R.

    2015-03-01

    In order to improve device performance of interconnects, the microelectronics industry utilizes low-k dielectric technology in place of traditional SiO2. Furthermore, titanium nitride (TiN) is being widely used as a hard mask to pattern low k materials such as SiOC:H into desired architectures with acoustic excitations and to measure their mode dispersions for incident light with wave-vector components parallel or perpendicular to the TiN wires. The results of measurements performed on samples with a range of wire dimensions (width/depth) will be presented that include the dependence of the Brillouin peak intensities on the incident and scattered light polarization as well as a model of the mode profiles.

  7. The damage of the optical components induced by the stimulated Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    Ge Zi-Ming; Lü Zhi-Wei; Cai Jun-Wei; Ao Shu-Yan; Luo You-Hua

    2006-01-01

    A theory of excitation of ultrasonic waves in the stimulated Brillouin scattering (SBS) process is presented in this paper. By using several reasonable approximations, a numerical calculation of the transient longitudinal SBS shows that large amplitude of acoustic waves can be built up by the nanosecond pulse of high-power laser, which may result in the damage of optical glasses. The maximal density change and the maximal acoustic wave intensity in optical glasses of 5 cm in thickness are calculated by using different parameters of the high-energy laser, such as the intensity, the pulse width, and the wave length. The damage threshold of the optical glasses is about 80 GW/cm2 when using a 1064 nm laser. The dynamic mechanism of SBS is the electrostriction effect of the components coupling with the high-power laser.

  8. Angle-resolved spin wave band diagrams of square antidot lattices studied by Brillouin light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G.; Tacchi, S. [Istituto Officina dei Materiali del Consiglio Nazionale delle Ricerche (IOM-CNR), Sede di Perugia, c/o Dipartimento di Fisica e Geologia, Via A. Pascoli, I-06123 Perugia (Italy); Montoncello, F.; Giovannini, L. [Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via G. Saragat 1, I-44122 Ferrara (Italy); Madami, M.; Carlotti, G. [Dipartimento di Fisica e Geologia, Università di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Ding, J.; Adeyeye, A. O. [Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-06-29

    The Brillouin light scattering technique has been exploited to study the angle-resolved spin wave band diagrams of squared Permalloy antidot lattice. Frequency dispersion of spin waves has been measured for a set of fixed wave vector magnitudes, while varying the wave vector in-plane orientation with respect to the applied magnetic field. The magnonic band gap between the two most dispersive modes exhibits a minimum value at an angular position, which exclusively depends on the product between the selected wave vector magnitude and the lattice constant of the array. The experimental data are in very good agreement with predictions obtained by dynamical matrix method calculations. The presented results are relevant for magnonic devices where the antidot lattice, acting as a diffraction grating, is exploited to achieve multidirectional spin wave emission.

  9. Depolarized guided acoustic wave Brillouin scattering in hollow-core photonic crystal fibers

    CERN Document Server

    Zhong, Wenjia Elser née; Elser, Dominique; Heim, Bettina; Marquardt, Christoph; Leuchs, Gerd

    2015-01-01

    By performing quantum-noise-limited optical heterodyne detection, we observe polarization noise in light after propagation through a hollow-core photonic crystal fiber (PCF). We compare the noise spectrum to the one of a standard fiber and find an increase of noise even though the light is mainly transmitted in air in a hollow-core PCF. Combined with our simulation of the acoustic vibrational modes in the hollow-core PCF, we are offering an explanation for the polarization noise with a variation of guided acoustic wave Brillouin scattering (GAWBS). Here, instead of modulating the strain in the fiber core as in a solid core fiber, the acoustic vibrations in hollow-core PCF influence the effective refractive index by modulating the geometry of the photonic crystal structure. This induces polarization noise in the light guided by the photonic crystal structure.

  10. The Photochemical Study of HSA and BSA with Resonance Light-Scattering and Fluorescence Spectra

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The resonance light-scattering (RLS) of human serum albumin (HSA) and bovine serum albumin (BSA) is reported for the first time, and applied to study photochemical reaction of HSA and BSA. The fact of photocrosslinking self-association effect in HSA and BSA solutions is identified by the enhancement of RLS. The fluorescence quenching at about 350 nm and 700 nm proves that tryptophan (Trp) residues are one of the photochemical activity sites in HSA and BSA molecules. The Rayleigh scattering (RS) spectra of HSA and BSA that were neglected in fluorescence spectra before are found at about 296 nm, 592 nm and 888 nm for the first time, and are of adventageous to studying the aggregation of HSA or BSA. The possible photochemical reaction mechanism is also proposed.

  11. Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

    Institute of Scientific and Technical Information of China (English)

    DONG Wu-qin; JIA Zhen-hong

    2008-01-01

    The relation between the power of the Brillouin signal and the swain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Brillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of thep arameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.

  12. Determination of the electron temperature in the modified ionosphere over HAARP using the HF pumped Stimulated Brillouin Scatter (SBS) emission lines

    OpenAIRE

    Bernhardt, P. A.; C. A. Selcher; Lehmberg, R. H.; Rodriguez, S; Thomason, J.; M. McCarrick; Frazer, G.

    2009-01-01

    An ordinary mode electromagnetic wave can decay into an ion acoustic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The first detection of this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. Subsequent experiments have provided additional verification of this process and quantitative interpretation of the scattered wave frequency offsets to yield m...

  13. A Brillouin scattering study of La0.77Ca0.23MnO3 across the metal-insulator transition

    International Nuclear Information System (INIS)

    Temperature-dependent Brillouin scattering studies have been carried out on La0.77Ca0.23MnO3 across the paramagnetic insulator-ferromagnetic metal (I-M) transition (TC ∼ 230 K). The spectra show modes corresponding to a surface Rayleigh wave (SRW) and a high velocity pseudo-surface wave (HVPSAW) along with bulk acoustic waves (B1 and B2). The Brillouin shifts associated with the SRW and HVPSAW increase, whereas the B1 and B2 frequencies decrease, below TC. The temperature dependence of the SRW and HVPSAW modes is related to the increase in the elastic constant C11 across the I-M transition. The decrease in frequency across the I-M transition of the bulk modes is understood to be due to enhanced self-energy corrections as a result of increased magnon-phonon interaction across the I-M transition. Correspondingly, these modes show a large increase in the full width at half maximum (FWHM) as the temperature decreases. We also observe a central peak whose width is maximum at TC

  14. Single Brillouin frequency shifted S-band multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier in ring cavity

    Science.gov (United States)

    Reshak, A. H.; Hambali, N. A. M. Ahmad; Shahimin, M. M.; Wahid, M. H. A.; Anwar, Nur Elina; Alahmed, Zeyad A.; Chyský, J.

    2016-10-01

    This paper is focusing on simulation and analyzing of S-band multi-wavelength Brillouin-Raman fiber laser performance utilizing fiber Bragg grating and Raman amplifier in ring cavity. Raman amplifier-average power model is employed for signal amplification. This laser system is operates in S-band wavelength region due to vast demanding on transmitting the information. Multi-wavelength fiber lasers based on hybrid Brillouin-Raman gain configuration supported by Raman scattering effect have attracted significant research interest due to its ability to produced multi-wavelength signals from a single light source. In multi-wavelength Brillouin-Raman fiber, single mode fiber is utilized as the nonlinear gain medium. From output results, 90% output coupling ratio has ability to provide the maximum average output power of 43 dBm at Brillouin pump power of 20 dBm and Raman pump power of 14 dBm. Furthermore, multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier is capable of generated 7 Brillouin Stokes signals at 1480 nm, 1510 nm and 1530 nm.

  15. CONTROL OF LASER RADIATION PARAMETERS: Stimulated-Brillouin-scattering compression of pulses from an Nd : YAG laser with a short cavity and measurement of the nonradiative relaxation time of the lower active level

    Science.gov (United States)

    Buzelis, R.; Dementjev, Aleksandr S.; Kosenko, E. K.; Murauskas, E.

    1995-06-01

    A short (~11 cm) cavity of an Nd : YAG laser was Q-switched by LiF : \\mathrm F^-_2 and GSGG : Cr3+ : Cr4+ : Nd3+ crystals. This resulted in stable generation of short (~2.5 ns) pulses with energies in excess of 6 mJ. Pulses with ~300 and ~150 mJ energies for the first and second harmonics, respectively, and of ~100 ps duration were obtained at the output of a stimulated-Brillouin-scattering compressor and a three-pass Nd : YAG amplifier. A study of the gain recovery after passage of a short saturating pulse through the active element yielded the upper limit (1 ns) of the nonradiative relaxation time of the 4I11/2 lower active level of the neodymium ion.

  16. Brillouin light scattering on MSW excitations in device structures (invited) (abstract)

    Science.gov (United States)

    Patton, Carl E.

    1987-04-01

    Magnetostatic wave (MSW) propagation in planar magnetic samples has formed the physical basis for most of the MSW device structures which have been developed in recent years. The properties of these waves, however, were accessible only by indirect means, usually in the form of the final device operating characteristics. With the technique of Brillouin light scattering (BLS), it is now possible to measure the dispersion properties and energy flow profiles of MSW excitations in situ in actual device configurations. The technique requires an incident low-power laser beam focused on the surface of the magnetic layer, some collection optics to sample the scattered light, and a sensitive, high-contrast Fabry-Perot interferometer for frequency analysis. In simple terms, one needs simply to ``bounce'' a laser beam off the active magnetic layer in the device in order to probe directly the excitations which make the device work. The technique is noninvasive and independent of any device function which the MSW signals serve. The BLS technique should prove to be a powerful diagnostic tool in the developing technology of MSW devices. The technique is broadband, and is capable of device diagnostics from the low GHz range up to frequencies in the THz regime.

  17. Study on the interaction between diphenhydramine and erythrosin by absorption, fluorescence and resonance Rayleigh scattering spectra

    Institute of Scientific and Technical Information of China (English)

    TANG XiaoLing; LIU ZhongFang; LIU ShaoPu; HU XiaoLi

    2007-01-01

    In pH 4.5 Britton-Robinson (BR) buffer solution, erythrosin (ET) can react with diphenhydramine (DP) to form a 1:1 ion-association complex, which not only results in the change of the absorption spectra, but also results in the great enhancement of resonance Rayleigh scattering (RRS) and the quenching of fluorescence. Furthermore, a new RRS spectrum will appear, and the maximum RRS wavelength was located at about 580 nm.In this work, the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reaction and the properties of an analytical chemistry were investigated. A sensitive, simple and new method for the determination of DP by using erythrosin as a probe has been developed. The detection limits for DP were 0.0020 μg/mL for RRS method, 0.088 μg/mL for absorption method and 0.094 μg/mL for fluorophotometry. There was a linear relationship between the absorbance, RRS and fluorescence intensities and the drug concentration in the range of 0.0067-2.0, 0.29-6.4 and 0.31-3.2 μg/mL, respectively. The effects of the interaction of diphenhydramine and erythrosin on the absorption, fluorescence and resonance Rayleigh scattering spectra were discussed. In light polarization experiment, the polarization of RRS at maximum wavelength was measured to be P = 0.9779, and it revealed that the RRS spectrum of DP-ET complex consists mostly of resonance scattering and few resonance fluorescence. In this study, enthalpy of formation and mean polarizability were calculated by AM1 quantum chemistry method. In addition, the reaction mechanism and the reasons for the enhancement of scattering spectra and the energy transfer between absorption, fluorescence and RRS were discussed.

  18. Brillouin Optomechanics in Coupled Silicon Microcavities

    CERN Document Server

    Espinel, Yovanny A V; Luiz, Gustavo O; Alegre, Thiago P M; Wiederhecker, Gustavo S

    2016-01-01

    The simultaneous control of optical and mechanical waves has enabled a range of fundamental and technological breakthroughs, from the demonstration of ultra-stable frequency reference devices to the exploration of the quantum-classical boundaries in laser-cooling experiments. More recently, such an opto-mechanical interaction has been observed in integrated nano-waveguides and microcavities in the Brillouin regime, where short-wavelength mechanical modes scatters light at several GHz. Here we engineer coupled optical microcavities spectra to enable a low threshold excitation of mechanical travelling-wave modes through backward stimulated Brillouin scattering. Exploring the backward scattering we propose microcavity designs supporting super high frequency modes ($\\sim25$ GHz) an large optomechanical coupling rates ($g_0/2\\pi \\sim 50$ kHz).

  19. Stable and tunable self-seeded multiwavelength Brillouin-erbium fiber laser with higher OSNR

    Science.gov (United States)

    Zou, Hui; Yang, Ruilan; Shen, Xiao; Wei, Wei

    2016-07-01

    A stable and tunable self-seeded multiwavelength Brillouin-erbium fiber laser (BEFL) is designed and demonstrated based on a Single-Mode-Multimode-Single-Mode (SMS) fiber filter. The SMS filter is fabricated by splicing a 15 cm long multimode fiber between two single mode fibers. The self-excited Brillouin pump is internally achieved by cascaded stimulated Brillouin scattering (SBS) in the single mode fiber. By applying axial strain (from 0 to 466.7 μɛ) to the SMS filter with the same step of 66.7 μɛ , the multiwavelength of the output laser is tuned from 1553.58 to 1559.79 nm correspondingly, and the tunable range is 6.21 nm. The generation of up to 16 Brillouin Stokes wavelengths with 30 dB optical signal to noise ratio (OSNR) are obtained.

  20. Classical ferroelectriclike behavior of highly ordered Pb (S c1 /2N b1 /2)O3 studied by dielectric and Brillouin scattering spectroscopy

    Science.gov (United States)

    Sivasubramanian, V.; Subramanian, V.; Kojima, S.

    2016-02-01

    The ferroelectric phase transition behavior in the highly ordered Pb (S c1 /2N b1 /2) O3 has been investigated by the dielectric and Brillouin spectroscopy. The dielectric permittivity ɛr exhibits a sharp maximum without any frequency dispersion at its Curie temperature Tc. In the temperature range far above Tc, it was noted that the dielectric permittivity exhibits a noticeable deviation from the Curie-Weiss law below the characteristic intermediate temperature T*=500 K , which is common to most of the Pb-based oxide perovskite relaxors. Upon cooling, the frequency of the longitudinal acoustic phonon mode exhibits a remarkable softening towards Tc. The relaxation time of the order parameter calculated using the Landau-Khalatnikov approach was determined to be more than one order of magnitude lower than that of the disordered Pb (S c1 /2N b1 /2)O3 and is very close to that observed in the paraelectric phase of the classical ferroelectric, BaTi O3 . The observed dielectric and relaxation features are qualitatively discussed in terms of the difference in the strength of the random electric fields.

  1. Micro-focused Brillouin light scattering: imaging spin waves at the nanoscale

    Directory of Open Access Journals (Sweden)

    Thomas eSebastian

    2015-06-01

    Full Text Available Spin waves constitute an important part of research in the field of magnetization dynamics. Spin waves are the elementary excitations of the spin system in a magnetically ordered material state and magnons are their quasi particles. In the following article, we will discuss the optical method of Brillouin light scattering (BLS spectroscopy which is a now a well established tool for the characterization of spin waves. BLS is the inelastic scattering of light from spin waves and confers several benefits: the ability to map the spin wave intensity distribution with spatial resolution and high sensitivity as well as the potential to simultaneously measure the frequency and the wave vector and, therefore, the dispersion properties.For several decades, the field of spin waves gained huge interest by the scientific community due to its relevance regarding fundamental issues of spindynamics in the field of solid states physics. The ongoing research in recent years has put emphasis on the high potential of spin waves regarding information technology. In the emerging field of textit{magnonics}, several concepts for a spin-wave based logic have been proposed and realized. Opposed to charge-based schemes in conventional electronics and spintronics, magnons are charge-free currents of angular momentum, and, therefore, less subject to scattering processes that lead to heating and dissipation. This fact is highlighted by the possibility to utilize spin waves as information carriers in electrically insulating materials. These developments have propelled the quest for ways and mechanisms to guide and manipulate spin-wave transport. In particular, a lot of effort is put into the miniaturization of spin-wave waveguides and the excitation of spin waves in structures with sub-micrometer dimensions.For the further development of potential spin-wave-based devices, the ability to directly observe spin-wave propagation with spatial resolution is crucial. As an optical

  2. Experimental Studies of the Stimulated Brillouin Scattering Instability in the Saturated Regime

    Energy Technology Data Exchange (ETDEWEB)

    Froula, D

    2002-10-29

    An experimental study of the stimulated Brillouin scattering (SBS) instability has investigated the effects of velocity gradients and kinetic effects on the saturation of ion-acoustic waves in a plasma. For intensities less than I < 1.5 x 10{sup 15} W cm{sup -2}, the SBS instability is moderated primarily by velocity gradients, and for intensities above this threshold, nonlinear trapping is invoked to saturate the instability. We report direct evidence of detuning of SBS by a velocity gradient which was achieved by directly measuring the frequency shift of the SBS driven acoustic wave relative to the local resonant acoustic frequency. Furthermore, a novel use of Thomson scattering has allowed us to gather direct evidence of kinetic effects associated with the SBS process. Specifically, a measured two-fold increase of the ion temperature has been linked with laser beam excitation of ion-acoustic waves to large amplitudes by the SBS instability. Ion-acoustic waves were excited to large amplitude with a 2{omega} 1.2-ns long interaction beam with intensities up to 5 x 10{sup 15} W cm{sup -2}. The local frequency, amplitude, and spatial range of these waves were measured with a 3{omega} 200ps Thomson-scattering probe beam. These detailed and accurate measurements in well-characterized plasma conditions allow for the first time a direct test of non-linear models of the saturation of SBS. The measured two-fold increase of the ion temperature and its correlation with SBS reactivity measurements is the first quantitative evidence of hot ions created by ion trapping in laser plasmas.

  3. Investigation on the effect of beam divergence angle upon output waveform based on stimulated Brillouin scattering optical limiting

    Institute of Scientific and Technical Information of China (English)

    Hasi Wu-Li-Ji; Lu Huan-Huan; Gong Sheng; Fu Mei-Ling; Lin Zhi-Wei; Lin Dian-Yang; He Wei-Ming

    2009-01-01

    This paper investigates the effect of beam divergence angle on output waveform based on stimulated Brillouin scattering optical limiting. Output waveforms in the case of different pump divergence angles are numerically simulated,and validated in a Nd:YAG seed-injected laser system. The results indicate that a small pump divergence angle can lead to good interaction between pump and Stokes, and a platform can be easily realized in the transmitted waveform.In contrast, a peak followed by the platform appears when the divergence angle becomes large.

  4. Determination of elastic stiffness coefficients of lead zirconate single crystals in the cubic phase by Brillouin light scattering

    International Nuclear Information System (INIS)

    The temperature dependence of the three independent elastic constants of antiferroelectric lead zirconate single crystals was determined in the cubic, paraelectric phase by Brillouin light scattering spectroscopy. Two longitudinal elastic moduli of C11 and (C11 + C12+2 C44)/2 showed softening upon cooling toward the phase transition temperature, indicating the coupling of the acoustic waves to the polarization fluctuations of the precursor polar clusters. Among the two transverse acoustic modes, C44 was almost constant while (C11-C12)/2 showed a noticeable softening in the paraelectric phase. This was attributed to the acoustic instability of lead zirconate toward the orthorhombic ground state

  5. Coherent Tiled 4 Beam Combination by Phase Controlled Stimulated Brillouin Scattering Phase Conjugation Mirrors toward the Practical Laser Fusion Driver

    International Nuclear Information System (INIS)

    Full text: The coherent beam combination using the phase controlled stimulated Brillouin scattering phase conjugate mirrors (SBS-PCMs) is one of the promising techniques for the practical laser fusion drivers. Its ability has been demonstrated experimentally through this work. The phase fluctuations of the titled beams are less than 1/25 wavelength even when the amplifiers are inserted and operated in the beam combining system, which means that this new technique can be applied to combine the currently available lasers such as 100 J/ns/10 Hz for a real laser driver module whose output energy is greater than 5 kJ/ns/10 Hz. (author)

  6. Phase-locked stimulated Brillouin scattering seeded by a transient acoustic wave excited through an optical interference field

    International Nuclear Information System (INIS)

    A mathematical description of an experimentally-verified scheme leading to a phase-locked stimulated Brillouin scattering (SBS) is presented. It is shown that this phase-locking of the SBS process may have its origin in a transient acoustic standing wave initiated by an arising optical interference field, eventually leading to a stationary density modulation of the medium. An appropriate solution was obtained by solving the acoustic wave-equation with electrostriction as a driving force. As a consequence of the damping term being included in this equation, the acoustic standing wave becomes gradually attenuated and, contrary to the undamped solution published earlier, thus constitutes a truly transient phenomenon.

  7. Mode conversion based on forward stimulated Brillouin scattering in a hybrid phononic-photonic waveguide.

    Science.gov (United States)

    Chen, Guodong; Zhang, Ruiwen; Sun, Junqiang; Xie, Heng; Gao, Ya; Feng, Danqi; Xiong, Huang

    2014-12-29

    We propose a scheme for on-chip all optical mode conversion based on forward stimulated Brillouin scattering in a hybrid phononic-photonic waveguide. To describe the mode conversion the theoretical model of the FSBS is established by taking into account the radiation pressure and the electrostriction force simultaneously. The numerical simulation is carried out for the mode conversion from the fundamental mode E11x to the higher-order mode E21x. The results indicate that the mode conversion efficiency is affected by the waveguide length and the input pump light power, and the highest efficiency can reach upto 88% by considering the influence of optical and acoustic absorption losses in the hybrid waveguide. Additionally, the conversion bandwidth with approximate 12.5 THz can be achieved in 1550nm communication band. This mode converter on-chip is a promising device in the integrated optical systems, which can effectively increase the capacity of silicon data busses for on-chip optical interconnections. PMID:25607172

  8. A Monte Carlo study of the energy spectra and transmission characteristics of scattered radiation from x-ray computed tomography

    International Nuclear Information System (INIS)

    Existing data used to calculate the barrier transmission of scattered radiation from computed tomography (CT) are based on primary beam CT energy spectra. This study uses the EGSnrc Monte Carlo system and Epp user code to determine the energy spectra of CT scatter from four different primary CT beams passing through an ICRP 110 male reference phantom. Each scatter spectrum was used as a broad-beam x-ray source in transmission simulations through seventeen thicknesses of lead (0.00–3.50 mm). A fit of transmission data to lead thickness was performed to obtain α, β and γ parameters for each spectrum. The mean energy of the scatter spectra were up to 12.3 keV lower than that of the primary spectrum. For 120 kVp scatter beams the transmission through lead was at least 50% less than predicted by existing data for thicknesses of 1.5 mm and greater; at least 30% less transmission was seen for 140 kVp scatter beams. This work has shown that the mean energy and half-value layer of CT scatter spectra are lower than those of the corresponding primary beam. The transmission of CT scatter radiation through lead is lower than that calculated with currently available data. Using the data from this work will result in less lead shielding being required for CT scanner installations. (paper)

  9. First E- and D-region incoherent scatter spectra observed over Jicamarca

    Directory of Open Access Journals (Sweden)

    J. L. Chau

    2006-07-01

    Full Text Available We present here the first Jicamarca observations of incoherent scatter radar (ISR spectra detected from E- and D-region altitudes. In the past such observations have not been possible at Jicamarca due a combined effect of strong equatorial electrojet (EEJ clutter and hardware limitations in the receiving system. The observations presented here were made during weak EEJ conditions (i.e., almost zero zonal electric field using an improved digital receiving system with a wide dynamic range and a high data throughput.

    The observed ISR spectra from E- and D-region altitudes are, as expected, narrow and get even narrower with decreasing altitude due to increasing ion-neutral collision frequencies. Therefore, it was possible to obtain accurate spectral measurements using a pulse-to-pulse data analysis. At lower altitudes in the D-region where signal correlation times are relatively long we used coherent integration to improve the signal-to-noise ratio of the collected data samples. The spectral estimates were fitted using a standard incoherent scatter (IS spectral model between 87 and 120 km, and a Lorentzian function below 110 km. Our preliminary estimates of temperature and ion-neutral collisions frequencies above 87 km are in good agreement with the MSISE-90 model. Below 87 km, the measured spectral widths are larger than expected, causing an overestimation of the temperatures, most likely due to spectral distortions caused by atmospheric turbulence.

  10. Transition from hydrodynamic to fast sound in a He-Ne mixture a neutron Brillouin scattering experiment

    CERN Document Server

    Bafile, U; Barocchi, F; Sampoli, M

    2002-01-01

    The presence of a fast-sound mode in the microscopic dynamics of the rare-gas mixture He-Ne, predicted by theoretical studies and molecular-dynamics simulations, was demonstrated by an inelastic neutron scattering experiment. In order to study the transition between the fast and the normal acoustic modes in the hydrodynamic regime, k values lower by about one order of magnitude than in the usual experiments have to be probed. We describe here the results of the first neutron Brillouin scattering experiment performed with this purpose on the same system already investigated at larger k. The results of both experiments, together with those of a new molecular-dynamics simulation, provide a complete and consistent description, still missing so far, of the onset of fast-sound propagation in a binary mixture. (orig.)

  11. Monitoring the distributed impact wave on a concrete slab due to the traffic based on polarization dependence on stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    For the first time to our knowledge, distributed impact waves due to the highway traffic on concrete slabs reinforced with FRP bars are monitored in real time using stimulated Brillouin scattering. The impact wave is caused by the traffic passing on the highway pavement at high speed (>100 km h−1), which induced pressure on the concrete slabs, and in turn created a local birefringence change, leading to variation of the local state of polarization change (SOP). The pump and probe waves of the stimulated Brillouin scattering 'see' the SOP change and react with a decrease of the Brillouin gain or loss signal, when the pump and probe waves have the same input polarization state. The frequency difference between the pump and probe waves are locked at the static-strain-related Brillouin frequency. Optical fiber was embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montréal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz. A spatial resolution of 2 m was used over a sensing length of 300 m

  12. Effect of large effective area fiber length on the performance of forward-backward scattering combination multiwavelength Brillouin-Raman fiber laser

    International Nuclear Information System (INIS)

    In this paper we experimentally demonstrate the effect of large effective area fiber length on the performance of a multiwavelength Brillouin–Raman fiber laser in which the forward and backward generated Stokes lines due to Brillouin scattering are combined together through a 3 dB coupler. Thus, the demonstrated laser is dubbed a forward–backward scattering combination multiwavelength Brillouin–Raman fiber laser (FBSC-MBRFL). This laser system utilizes a large effective area fiber and a dispersion compensating fiber that act as Brillouin and Raman gain media, respectively. It is demonstrated that by employing forward pumping schemes, the demonstrated laser system is capable of generating a good flat amplitude Brillouin Stokes line with an average optical to noise ratio of 17 dB along the spectral spans. However, the backward pumping scheme is able to produced high bandwidth spans. At the optimal large effective area fiber length of 50 km, a Raman pump power of 1100 mW at Brillouin pump wavelengths of 1550 mm and 1560 nm is identified to produce the maximum bandwidth with values of approximately 28.45 nm and 24.08 nm, respectively. (paper)

  13. Investigation of ionospheric stimulated Brillouin scatter generated at pump frequencies near electron gyroharmonics

    Science.gov (United States)

    Mahmoudian, A.; Scales, W. A.; Bernhardt, P. A.; Fu, H.; Briczinski, S. J.; McCarrick, M. J.

    2013-11-01

    Stimulated Electromagnetic Emissions (SEEs), secondary electromagnetic waves excited by high power electromagnetic waves transmitted into the ionosphere, produced by the Magnetized Stimulated Brillouin Scatter (MSBS) process are investigated. Data from four recent research campaigns at the High Frequency Active Auroral Research Program (HAARP) facility is presented in this work. These experiments have provided additional quantitative interpretation of the SEE spectrum produced by MSBS to yield diagnostic measurements of the electron temperature and ion composition in the heated ionosphere. SEE spectral emission lines corresponding to ion acoustic (IA) and electrostatic ion cyclotron (EIC) mode excitation were observed with a shift in frequency up to a few tens of Hz from the pump frequency for heating near the third harmonic of the electron gyrofrequency 3fce. The threshold of each emission line has been measured by changing the pump wave power. The excitation threshold of IA and EIC emission lines originating at the reflection and upper hybrid altitudes is measured for various beam angles relative to the magnetic field. Variation of strength of MSBS emission lines with pump frequency relative to 3fce and 4fce is also studied. A full wave solution has been used to estimate the amplitude of the electric field at the interaction altitude. The estimated instability threshold using the theoretical model is compared with the threshold of MSBS lines in the experiment and possible diagnostic information for the background ionospheric plasma is discussed. Simultaneous formation of artificial field-aligned irregularities (FAIs) and suppression of the MSBS process is investigated. This technique can be used to estimate the growth time of artificial FAIs which may result in determination of plasma waves and physical process involved in the formation of FAIs.

  14. Diagnostic techniques for photonic materials based on Raman and Brillouin spectroscopies

    Institute of Scientific and Technical Information of China (English)

    M. Mattarelli; M. Ferrari; Y. Jestin; G. Nunzi Conti; S. Pelli; G.C. Righini; S.Caponi; A. Chiappini; M. Montagna; E. Moser; F. Rossi; C.Tosello; C. Armellini; A. Chiasera

    2007-01-01

    The elastic and vibrational properties of a material, bulk or planar waveguide, are studied by Brillouin and Raman spectroscopy to follow the process of nanocrystals growth in glass-ceramics. The nanoparticles cause the appearance, in the low frequency Raman spectrum, of characteristic peaks, whose position depends on the size of the crystals. At the same time, sharp crystal peaks, due to optical phonons, appear in the Raman spectra, allowing the determination of the nucleated phase, and a frequency shift of the Brillouin peaks is observed.

  15. Low energy nuclear scattering and sub-threshold spectra from a multi-channel algebraic scattering theory

    OpenAIRE

    Amos, K.; Fraser, P.; Karataglidis, S.; van der Knijff, D.; Svenne, J. P.; Canton, L.; Pisent, G.

    2005-01-01

    A multi-channel algebraic scattering theory, to find solutions of coupled-channel scattering problems with interactions determined by collective models, has been structured to ensure that the Pauli principle is not violated. Positive (scattering) and negative (sub-threshold) solutions can be found to predict both the compound nucleus sub-threshold spectrum and all resonances due to coupled channel effects that occur on a smooth energy varying background.

  16. Characterization of Brillouin fiber generator and amplifier for optimized working condition of distributed sensors

    Science.gov (United States)

    Ravet, Fabien; Bao, Xiaoyi; Snoddy, Jeff; Li, Yun; Chen, Liang

    2009-06-01

    The Brillouin fiber amplifier (BFA) has been used in Brillouin optical time and frequency domain analyzer based sensors. For BFA based distributed sensor the optimized working condition is to have the highest Brillouin gain, i.e., highest SNR, which avoids high pump depletion induced gain saturation. We have found that the optimum working condition for distributed sensor system is associated with the stimulated Brillouin scattering (SBS) threshold for BFA, which can be experimentally determined with Stokes power inflexion and/or Stokes spectrum linewidth minimum methods. This threshold depends on both pump and probe power instead of just the pump power as in Brillouin fiber generator (BFG), as well as on sensing length as confirmed by our experimental results and theoretical simulation. This was achieved by introducing the concept of absorption coefficient of the sensing medium defined as the ratio of the total output power to the total input power. We find that the medium absorption is minimized when input Stokes power is an order of magnitude lower than BFA threshold. This minimum is a signature of the balance between maximum Stokes gain and pump depletion which is also the reason why Stokes spectrum linewidth goes through a minimum.

  17. Self-focusing induced reduction of Stimulated Brillouin Scattering for the case of monospeckle laser beams interacting with a plasma

    Science.gov (United States)

    Masson-Laborde, Paul-Edouard; Hueller, Stefan; Pesme, Denis; Loiseau, Pascal; Labaune, Christine; Bandulet, Heidi

    2008-11-01

    The mechanism explaining the low level of Stimulated Brillouin Scattering observed in laser-plasma experiments with monospeckle laser beams, carried out at the LULI facility, is studied by means of numerical simulations. For the regime where the beam power is well above the self-focusing critical power, simulations carried out with the codes Harmony2D and HERA-ILP (in 2D and 3D geometry respectively), show time-averaged reflectivities of the order of only a few percent. Because of self-focusing and the filament resonant instability, SBS takes only place in self-focused hot spots located in the low-density front part of the plasma. The shortened hot spot sizes and the steepened flow-profile dramatically reduce SBS. This scenario may also applies to the most intense laser hot spots in a spatially smoothed laser beam.

  18. Micromagnetic study of CoPt-SiO2 granular films by spin-wave Brillouin scattering

    International Nuclear Information System (INIS)

    A spin-wave Brillouin scattering study of a CoPt-SiO2 granular magnetic recording medium was made. This film contains ferromagnetic CoPt particles in a SiO2 matrix, and has an extremely low medium noise property due to little exchange coupling between magnetic grains. Spin waves of both the propagating surface mode and standing wave mode were found to be excited in granular magnetic films with various microstructures. A possible origin of the spin wave is a magnetostatic coupling between regularly ordered CoPt grains, as reported for artificially patterned magnetic thin films. This result shows two promising features of the CoPt-SiO2 granular film for high density recording medium: It is an ordered media obtained in a self-organizing manner, and it is less influenced by the thermal fluctuation effect, which is a serious problem for current high density magnetic recording. (c) 2000 American Institute of Physics

  19. Size-dependent magnetization dynamics in individual Ni80Fe20 disk using micro-focused Brillouin Light Scattering spectroscopy

    Science.gov (United States)

    Shimon, G.; Adeyeye, A. O.

    2015-09-01

    A direct and systematic investigation of the magnetization dynamics in individual circular Ni80Fe20 disk of diameter (D) in the range from 300 nm to 1 μm measured using micro-focused Brillouin Light Scattering (μ-BLS) spectroscopy is presented. At high field, when the disks are in a single domain state, the resonance frequency of the uniform center mode is observed to reduce with reducing disk's diameter. For D = 300 nm, additional edge and end-domains resonant modes are observed due to size effects. At low field, when the disks are in a vortex state, a systematic increase of resonant frequency of magnetostatic modes in a vortex state with the square root of the disks' aspect ratio (thickness divided by radius) is observed. Such dependence diminishes for disks with larger aspect ratio due to an increasing exchange energy contribution. Micromagnetic simulations are in excellent agreement with the experiments.

  20. Brillouin light scattering study of transverse mode coupling in confined yttrium iron garnet/barium strontium titanate multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Bublikov, K. V.; Grishin, S. V.; Sheshukova, S. E.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

    2015-11-28

    Using the space-resolved Brillouin light scattering spectroscopy we study the transformation of dynamic magnetization patterns in a bilayer multiferroic structure. We show that in the comparison with a single yttrium iron garnet (YIG) film magnetization distribution is transformed in the bilayer structure due to the coupling of waves propagating both in an YIG film (magnetic layer) and in a barium strontium titanate slab (ferroelectric layer). We present a simple electrodynamic model using the numerical finite element method to show the transformation of eigenmode spectrum of confined multiferroic. In particular, we demonstrate that the control over the dynamic magnetization and the transformation of spatial profiles of transverse modes in magnetic film of the bilayer structure can be performed by the tuning of the wavevectors of transverse modes. The studied confined multiferroic stripe can be utilized for fabrication of integrated dual tunable functional devices for magnonic applications.

  1. Single-crystal Brillouin spectroscopy with CO{sub 2} laser heating and variable q

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jin S.; Bass, Jay D. [Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Zhu, Gaohua [Materials Research Department, Toyota Research Institute of North America, Ann Arbor, Michigan 48105 (United States)

    2015-06-15

    We describe a Brillouin spectroscopy system integrated with CO{sub 2} laser-heating and Raman spectroscopic capabilities. Temperature is determined by measurements of the grey-body thermal radiation emitted by the hot sample, with the system response calibrated relative to a standard tungsten ribbon lamp. High-pressure laser-heating Brillouin scattering measurements of acoustic velocities on liquid water and ice compressed in a diamond-anvil cell were performed at temperatures up to 2500 ± 150 K at high pressure. Single-crystal laser-heating Brillouin measurements were made on the (111) plane of San Carlos olivine at ∼13 GPa, 1300 ± 200 K. The pressure as measured by ruby fluorescence is shown to be within ±0.5 GPa of the pressure on the olivine sample during laser heating when KCl and KBr are used as pressure-transmitting media. In addition, the system is designed for continuously variable scattering angles from forward scattering (near 0° scattering angle) up to near back scattering (∼141°). This novel setup allows us to probe a wide range of wave vectors q for investigation of phonon dispersion on, for example, crystals with large unit cells (on the scale of hundreds of nm)

  2. Single-crystal Brillouin spectroscopy with CO2 laser heating and variable q

    Science.gov (United States)

    Zhang, Jin S.; Bass, Jay D.; Zhu, Gaohua

    2015-06-01

    We describe a Brillouin spectroscopy system integrated with CO2 laser-heating and Raman spectroscopic capabilities. Temperature is determined by measurements of the grey-body thermal radiation emitted by the hot sample, with the system response calibrated relative to a standard tungsten ribbon lamp. High-pressure laser-heating Brillouin scattering measurements of acoustic velocities on liquid water and ice compressed in a diamond-anvil cell were performed at temperatures up to 2500 ± 150 K at high pressure. Single-crystal laser-heating Brillouin measurements were made on the (111) plane of San Carlos olivine at ˜13 GPa, 1300 ± 200 K. The pressure as measured by ruby fluorescence is shown to be within ±0.5 GPa of the pressure on the olivine sample during laser heating when KCl and KBr are used as pressure-transmitting media. In addition, the system is designed for continuously variable scattering angles from forward scattering (near 0° scattering angle) up to near back scattering (˜141°). This novel setup allows us to probe a wide range of wave vectors q for investigation of phonon dispersion on, for example, crystals with large unit cells (on the scale of hundreds of nm).

  3. Pushing the limit of the distributed Brillouin sensors for the sensing length and the spatial resolution

    Science.gov (United States)

    Bao, Xiaoyi; Liang, Hao; Dong, Yongkang; Li, Wenhai; Li, Yun; Chen, Liang

    2010-04-01

    Long distance sensing based on Brillouin scattering with centimeter spatial resolution, and yet high strain or temperature resolution requires the optimization of the optical and electronic system. In optical domain the limiting factors include gain saturation of the Stokes signal and pump depletion induced the Brillouin spectrum distortion, and thus a low gain is desired that requires low pump power, which sets a limit in the signal to noise ratio (SNR). The detection system must have high gain and narrow bandwidth to reduce electronic noise. The coded pulse offers the best solution as a low power solution of long distance sensing based on BOTDA to improve the signal to noise ratio (SNR), comparing two most common used formats: non-return-to-zero (NRZ) and return-to-zero (RZ), RZ coded pulses offer minimum distortion in the spatial resolution and the Brillouin spectrum, because the signal in RZ format returns to zero in very bit, while in NRZ coded pulse the signal returns to zero after continuous "1"s, which brings the higher gain and lower bandwidth comparing that in RZ coded pulse for BOTDA system. Hence NRZ coded pulse BOTDA would introduce spatial broadening and lower the spatial resolution. With minimum distortion of RZ signal we can use differential Brillouin gain to realize DPP-BOTDA technique for sub-meter spatial resolution. The minimum coded pulse width must be larger than the acoustic wave relaxation time to avoid the distorted Brillouin gain spectrum. Using LEAF fiber we achieved 50km sensing length and 50cm spatial resolution with the strain resolution of 8μɛ which is equivalent to 0.7MHz Brillouin frequency shift, this is the 1st sub-meter spatial resolution for 50km sensing length combined with high strain resolution.

  4. Study on Frequency Doubling Scattering and Second—Order Scattering Spectra of Heparin—Methylene Blue System

    Institute of Scientific and Technical Information of China (English)

    刘绍璞; 罗红群; 李念兵; 刘忠芳

    2003-01-01

    Binding of heparin with methylene blue(MB) in pH5.7 Britton-Robinson buffer can result in a significant enhancement of frequency doubling scattering (FDS) and second-order scattering (SOS).Their maximum scattering wavelengths(λmax) appear at 350nm for FDS and 700nm for SOS,respectively.The optimum conditions of the reaction,the influencing factors and the relationship between the two scattering intensities and the concentration of heparin have been investigated.The new methods for the determination of trace amounts of heparin bassed on the FDS and SOS methods have been developed,which exhibit high sensitivities.The detection limits of heparin are 4.36ng/mL for the FDS method and 3.55ng/mL for the SOS method,respectively.Both of the methods have fairly godd selectivity and ware applied to the determination of heparin in sodium heparinate injection samples with satisfactory results.Moreover,the relative mechamisms have also been discussed.

  5. Determination of the electron temperature in the modified ionosphere over HAARP using the HF pumped Stimulated Brillouin Scatter (SBS emission lines

    Directory of Open Access Journals (Sweden)

    P. A. Bernhardt

    2009-12-01

    Full Text Available An ordinary mode electromagnetic wave can decay into an ion acoustic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS. The first detection of this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009 using the HAARP transmitter in Alaska. Subsequent experiments have provided additional verification of this process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere. Using the SBS technique, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave may also be produced by the generalized SBS processes. Based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values.

  6. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)

    2014-08-15

    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  7. Stimulated Brillouin scattering phase-locking using a transient acoustic standing wave excited through an optical interference field

    International Nuclear Information System (INIS)

    Complete text of publication follows. Analytical description of an experimentally verified scheme leading to a phase-locked stimulated Brillouin scattering (SBS), used in a laser beam combination systems, is presented. The essential condition for the phase-locking effect for SBS is the fixation of the starting position and time of the acoustic Brillouin wave. It is shown that the starting position fixation of this acoustic wave may have its origin in a transient acoustic standing wave initiated by an arising optical interference field produced by the back-seeding concave mirror. This interference field leads to a stationary density modulation of the medium. However, the way to the formation of this density modulation leads via the acoustic standing wave. An appropriate solution, in the form of the standing wave, was obtained from solving the acoustic wave-equation using the electrostriction as a driving force. As a consequence of the damping term included in this equation the acoustic standing wave becomes gradually attenuated and contrary to the undamped solution published earlier, thus constitutes a truly transient phenomenon. Using a mathematical formalism similar to that which is used for the SBS description in the case of a random phase, the coupled equations describing the phase-locked SBS were derived. Contrary to the case without the back-seeding mirror, where the wave chosen from the thermal noise background subsequently plays the role of a trigger of the stimulated process, in this case it is replaced by the transient standing wave produced as a consequence of the presence of an optical interference field arisen in the focal region of the back-seeding concave mirror.

  8. Brillouin Cooling in a Linear Waveguide

    CERN Document Server

    Chen, Yin-Chung; Bahl, Gaurav

    2016-01-01

    Brillouin scattering is rarely considered as a mechanism that can cause cooling of a material due to the thermodynamic dominance of Stokes scattering in most practical systems. However, it has been shown in experiments on resonators that net phonon annihilation through anti-Stokes Brillouin scattering can be enabled by means of a suitable set of optical and acoustic states. The cooling of traveling phonons in a linear waveguide, on the other hand, could lead to the exciting future prospect of manipulating unidirectional heat fluxes and even the nonreciprocal transport of quantum information via phonons. In this work, we present the first analysis of the conditions under which Brillouin cooling may be achieved in a linear waveguide. We analyze the three-wave mixing interaction between the optical and acoustic modes that participate in forward Brillouin scattering, and reveal the key regimes of operation for the process. Our calculations indicate that measurable cooling may occur in state-of-the-art systems whe...

  9. Effect of the magnetic field on coexisting stimulated Raman and Brillouin backscattering of an extraordinary mode

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, Ashish, E-mail: ashishvyas.optics@gmail.com; Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, R. P., E-mail: rpsharma@ces.iitd.ernet.in [Centre for Energy Studies, IIT Delhi, Delhi 110016 (India)

    2016-01-15

    This paper presents a model to study the interplay between the stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in the presence of background magnetic field. This formalism is applicable to laser produced plasma as well as to heating mechanism in toroidal system by an extraordinary electromagnetic wave. In the former case, the magnetic field is self-generated, while in the latter case (toroidal plasmas) magnetic field is applied externally. The behavior of one scattering process is explicitly dependent on the coexisting scattering process as well as on the magnetic field. Explicit expressions for the back-reflectivity of scattered beams (SRS and SBS) are presented. It has been demonstrated that due to the magnetic field and coexistence of the scattering processes (SRS and SBS) the back-reflectivity gets modified significantly. Results are also compared with the three wave interaction case (isolated SRS or SBS case)

  10. Real-time detection and characterization of individual flowing airborne biological particles: fluorescence spectra and elastic scattering measurements

    Science.gov (United States)

    Pan, Yongle; Holler, Stephen; Chang, Richard K.; Hill, Steven C.; Pinnick, Ronald G.; Niles, Stanley; Bottiger, Jerold R.; Bronk, Burt V.

    1999-11-01

    Real-time methods which is reagentless and could detect and partially characterize bioaerosols are of current interest. We present a technique for real-time measurement of UV-excited fluorescence spectra and two-dimensional angular optical scattering (TAOS) from individual flowing biological aerosol particles. The fluorescence spectra have been observed from more than 20 samples including Bacillus subtilis, Escherichia coli, Erwinia herbicola, allergens, dust, and smoke. The S/N and resolution of the spectra are sufficient for observing small lineshape differences among the same type of bioaerosol prepared under different conditions. The additional information from TAOS regarding particle size, shape, and granularity has the potential of aiding in distinguishing bacterial aerosols from other aerosols, such as diesel and cigarette smoke.

  11. A wavelength-dispersive instrument for characterizing fluorescence and scattering spectra of individual aerosol particles on a substrate

    Science.gov (United States)

    Huffman, Donald R.; Swanson, Benjamin E.; Huffman, J. Alex

    2016-08-01

    We describe a novel, low-cost instrument to acquire both elastic and inelastic (fluorescent) scattering spectra from individual supermicron-size particles in a multi-particle collection on a microscope slide. The principle of the device is based on a slitless spectroscope that is often employed in astronomy to determine the spectra of individual stars in a star cluster but had not been applied to atmospheric particles. Under excitation, most commonly by either a 405 nm diode laser or a UV light-emitting diode (LED), fluorescence emission spectra of many individual particles can be determined simultaneously. The instrument can also acquire elastic scattering spectra from particles illuminated by a white-light source. The technique also provides the ability to detect and rapidly estimate the number fraction of fluorescent particles that could contaminate a collection of non-fluorescent material, even without analyzing full spectra. Advantages and disadvantages of using black-and-white cameras compared to color cameras are given. The primary motivation for this work has been to develop an inexpensive technique to characterize fluorescent biological aerosol particles, especially particles such as pollen and mold spores that can cause allergies. An example of an iPhone-enabled device is also shown as a means for collecting data on biological aerosols at lower cost or by utilizing citizen scientists for expanded data collection.

  12. Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Saleh, Khaldoun; Martinenghi, Romain; Beugnot, Jean-Charles; Sylvestre, Thibaut; Chembo, Yanne K

    2015-01-01

    We report the observation of stimulated Brillouin scattering and lasing at 1550~nm in barium fluoride (BaF$_2$) crystal. Brillouin lasing was achieved with ultra-high quality ($Q$) factor monolithic whispering gallery mode (WGM) mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from $8.2$ GHz up to $49$ GHz have been generated through cascaded Brillouin lasing. BaF$_2$ resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

  13. Study on the interaction between fluoroquinolones and erythrosine by absorption, fluorescence and resonance Rayleigh scattering spectra and their application

    Science.gov (United States)

    Wang, Jian; Liu, Zhongfang; Liu, Jiangtao; Liu, Shaopu; Shen, Wei

    2008-03-01

    In pH 4.4-4.5 Britton-Robinson (BR) buffer solution, fluoroquinolone antibiotics (FLQs) including ciprofloxacin (CIP), norfloxacin (NOR), levofloxacin (LEV) and lomefloxacin (LOM) could react with erythrosine (Ery) to form 1:1 ion-association complexes, which not only resulted in the changes of the absorption spectra and the quenching of fluorescence, but also resulted in the great enhancement of resonance Rayleigh scattering (RRS). These offered some indications of the determination of fluoroquinolone antibiotics by spectrophotometric, fluorescence and resonance Rayleigh scattering methods. The detection limits for fluoroquinolone antibiotics were in the range of 0.097-0.265 μg/mL for absorption methods, 0.022-0.100 μg/mL for fluorophotometry and 0.014-0.027 μg/mL for RRS method, respectively. Among them, the RRS method had the highest sensitivity. In this work, the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reactions and the properties of the analytical chemistry were investigated. The methods have been successfully applied to determination of some fluoroquinolone antibiotics in human urine samples and tablets. Taking CIP-Ery system as an example, the charge distribution, the enthalpy of formation and the mean polarizability were calculated by density function theory (DFT) method. In addition, the reasons for the enhancement of scattering spectra were discussed.

  14. Experimental analysis on the rapid measurement of a high precision Brillouin scattering spectrum in water using a Fabry-Pérot etalon

    Science.gov (United States)

    Zhou, Bo; Fan, Qiming; Ma, Yong; Yao, Yuan; Li, Hao; Huang, Jun; Liang, Kun

    2016-05-01

    The Brillouin lidar system with a Fabry-Pérot (F-P) etalon has been widely used in remote sensing to study ocean characteristics such as temperature, sound speed, etc. In this system, the measurement error stemming from the spectral broadening of an F-P etalon was typically neglected in applications where high measurement accuracy was not essential. In this paper, an integration method on radius and a convolution method on frequency are proposed to remove the broadening effect and improve the measurement accuracy, respectively. Experiments of underwater Brillouin scattering show that both fitting methods effectively reduce the measurement error due to the transmission function of an F-P etalon. A temperature accuracy of 0.1 °C and a salinity accuracy of 0.5‰ were achieved. Moreover, with the convolution method, the computational cost was reduced to 3 s, which enables rapid measurement of Brillouin shift and linewidth and makes the on-line remote sensing applications possible.

  15. Envelope broadening and scattering attenuation of a scalar wavelet in random media having power-law spectra

    Science.gov (United States)

    Sato, Haruo

    2016-01-01

    Peak delay and envelope broadening of an S-wavelet with travel distance increasing are seen in short-period seismograms of small earthquakes. Those phenomena are results of scattering by random velocity inhomogeneities in the earth medium. As shown in sonic well-log data we may suppose that random velocity fluctuation has power-law spectra even in the seismic spectral range. As a simple mathematical model, we study how the envelope of a scalar wavelet varies in von Kármán-type random media, which have power-law spectra at large wavenumbers. Since the centre wavenumber of a wavelet is a unique scale in the power-law spectral range, using it as a reference, we divide the random media into the low-wavenumber spectral (long-scale) component and the high-wavenumber spectral (short-scale) component. For the wave propagation through the long-scale component of random media, we may apply the parabolic approximation to the wave equation. Using the Markov approximation, which is a stochastic extension of the phase screen method, we directly synthesize the energy density, which is the mean-square (MS) envelope of a wavelet in a given frequency band. The envelope duration increases according to the second power of travel distance. There is an additional factor, the wandering effect which increases the envelope duration according to the traveltime fluctuation. Wide angle scattering caused by the short-scale component of random media attenuates wave amplitude with travel distance increasing. We use the total scattering coefficient of the short-scale component as a measure of scattering attenuation per distance, which is well described by the Born approximation. Multiplying the exponential scattering attenuation factor by the MS envelope derived by the Markov approximation, we can synthesize the MS envelope reflecting all the spectral components of random media. When the random medium power spectra have a steep role-off at large wavenumbers, the envelope broadening is small and

  16. An experimental investigation of stimulated Brillouin scattering in laser-produced plasmas relevant to inertial confinement fusion

    International Nuclear Information System (INIS)

    Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS impedes controlled fusion since it can scatter much or all of the incident laser light, resulting in poor drive symmetry and inefficient laser-plasma coupling. It is widely believed that SBS becomes convectively unstable--that is, it grows as it traverses the plasma. Though it has yet to be definitively tested, convective theory is often invoked to explain experimental observations, even when one or more of the theory's assumptions are violated. In contrast, the experiments reported here not only obeyed the assumptions of the theory, but were also conducted in plasmas with peak densities well below quarter-critical density. This prevented other competing or coexisting phenomena from occurring, thereby providing clearly interpretable results. These are the first SBS experiments that were designed to be both a clear test of linear convective theory and pertinent to controlled fusion research. A crucial part of this series of experiments was the development of a new instrument, the Multiple Angle Time Resolving Spectrometer (MATRS). MATRS has the unique capability of both spectrally and temporally resolving absolute levels of scattered light at many angles simultaneously, and is the first of its kind used in laser-plasma experiments. A detailed comparison of the theoretical predictions and the experimental observations is made

  17. Study on the interaction between diphenhydramine and erythrosin by absorption,fluorescence and resonance Rayleigh scattering spectra

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In pH 4.5 Britton-Robinson(BR)buffer solution,erythrosin(ET)can react with diphenhydramine(DP)to form a 1:1 ion-association complex,which not only results in the change of the absorption spectra,but also results in the great enhancement of resonance Rayleigh scattering(RRS)and the quenching of fluorescence.Furthermore,a new RRS spectrum will appear,and the maximum RRS wavelength was located at about 580 nm.In this work,the spectral characteristics of the absorption,fluorescence and RRS,the optimum conditions of the reaction and the properties of an analytical chemistry were inves- tigated.A sensitive,simple and new method for the determination of DP by using erythrosin as a probe has been developed.The detection limits for DP were 0.0020μg/mL for RRS method,0.088μg/mL for absorption method and 0.094μg/mL for fluorophotometry.There was a linear relationship between the absorbance,RRS and fluorescence intensities and the drug concentration in the range of 0.0067-2.0, 0.29-6.4 and 0.31-3.2μg/mL,respectively.The effects of the interaction of diphenhydramine and erythrosin on the absorption,fluorescence and resonance Rayleigh scattering spectra were discussed. In light polarization experiment,the polarization of RRS at maximum wavelength was measured to be P =0.9779,and it revealed that the RRS spectrum of DP-ET complex consists mostly of resonance scat- tering and few resonance fluorescence.In this study,enthalpy of formation and mean polarizability were calculated by AM1 quantum chemistry method.In addition,the reaction mechanism and the rea- sons for the enhancement of scattering spectra and the energy transfer between absorption,fluores- cence and RRS were discussed.

  18. Brillouin suppression in a fiber optical parametric amplifier by combining temperature distribution and phase modulation

    DEFF Research Database (Denmark)

    Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel;

    2008-01-01

    We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation.......We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation....

  19. Stimulated Brillouin scattering reduction induced by self-focusing for a single laser speckle interacting with an expanding plasma

    Energy Technology Data Exchange (ETDEWEB)

    Masson-Laborde, P. E.; Depierreux, S.; Loiseau, P. [CEA, DAM, DIF, F-91297 Arpajon Cedex (France); Hüller, S.; Pesme, D. [Centre de Physique Théorique (CPHT), CNRS, École Polytechnique, 91128 Palaiseau Cedex (France); Labaune, Ch. [LULI, CNRS, Université Pierre et Marie Curie, École Polytechnique, 91128 Palaiseau Cedex (France); Bandulet, H. [Institut National de la Recherche Scientifique (INRS), Varennes, Québec J3X1S2 (Canada)

    2014-03-15

    The origin of the low level of stimulated Brillouin scattering (SBS) observed in laser-plasma experiments carried out with a single laser speckle is investigated by means of three-dimensional simulations and modeling in the limit when the laser beam power P is well above the critical power for ponderomotive self-focusing We find that the order of magnitude of the time averaged reflectivities, together with the temporal and spatial SBS localization observed in our simulations, are correctly reproduced by our modeling. It is observed that, after a short transient stage, SBS reaches a significant level only (i) as long as the incident laser pulse is increasing in amplitude and (ii) in a single self-focused speckle located in the low-density front part of the plasma. In order to describe self-focusing in an inhomogeneous expanding plasma, we have derived a new Lagrangian density describing this process. Using then a variational approach, our model reproduces the position and the peak intensity of the self-focusing hot spot in the front part of the plasma density profile as well as the local density depletion in this hot spot. The knowledge of these parameters then makes it possible to estimate the spatial amplification of SBS as a function of the laser beam power and consequently to explain the experimentally observed SBS reflectivity, considerably reduced with respect to standard theory in the regime of large laser beam power.

  20. Damage detection in a cantilever beam under dynamic conditions using a distributed, fast, and high spatial resolution Brillouin interrogator

    Science.gov (United States)

    Motil, A.; Davidi, R.; Bergman, A.; Botsev, Y.; Hahami, M.; Tur, M.

    2016-05-01

    The ability of Brillouin-based fiber-optic sensing to detect damage in a moving cantilever beam is demonstrated. A fully computerized, distributed and high spatial resolution (10cm) Fast-BOTDA interrogator (50 full-beam Brillouin-gain-spectra per second) successfully directly detected an abnormally stiffened (i.e., `damaged') 20cm long segment in a 6m Aluminum beam, while the beam was in motion. Damage detection was based on monitoring deviations of the measured strain distribution along the beam from that expected in the undamaged case.

  1. Optical coherent detection Brillouin distributed optical fiber sensor based on orthogonal polarization diversity reception

    Institute of Scientific and Technical Information of China (English)

    Muping Song; Bin Zhao; Xianmin Zhang

    2005-01-01

    In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel detecting scheme is presented and demonstrated experimentally, which adopts orthogonal polarization diversity reception to resolve the polarization correlated detection problem. A laser is used as pump and reference light sources, a microwave electric-optical modulator (EOM) is adopted to produce frequency shift reference light, a polarization controller is used to control the polarization of the reference light which is changed into two orthogonal polarization for two adjacent acquisition periods. The Brillouin scattering light is coherently detected with the reference light, and the Brillouin scattering optical signal is taken out based on Brillouin frequency shift. After electronic processing, better Brillouin distributed sensing signal is obtained. A 25-km Brillouin distributed optical fiber sensor is achieved.

  2. Characteristics of perfluorinated amine media for stimulated Brillouin scattering in hundreds of picoseconds pulse compression at 532 nm

    Institute of Scientific and Technical Information of China (English)

    Wuliji Hasi; Hang Zhao; Dianyang Lin; Weiming He; Zhiwei Lü

    2015-01-01

    The characteristics of stimulated Brillouin scattering (SBS) in perfluorinated amine media and the experimental structure used in hundreds of picoseconds pulse compression at 532 nm are demonstrated.A two-stage SBS pulse compression structure is adopted for this work.The compact double-cell SBS compression structure and the scattering media FC-70 are chosen to compress the incident light from 9.5 to about 1 ns in the first stage.Then,the light is used as the pumping source for the second pulse compression.In the second stage,using a single-cell SBS structure in a pulse compression system,perfluorinated amine media with different phonon lifetimes,such as FC-3283,FC-40,FC-43,and FC-70,are chosen to run the comparative experimental study.The narrowest compressed pulse times obtained are 294,274,277,and 194 ps;they respectively correspond to the above listed media.The average width of the compressed pulse width is 320 ps for FC-3283,with a fluctuation range of 87 ps.For FC-40,the average pulse width is 320 ps,with a fluctuation range of 72 ps.And for FC-43,the average pulse width is 335 ps,with a fluctuation range of 88 ps.However,the average pulse width is only 280 ps for FC-70,with a fluctuation range of 57 ps.The highest energy reflectivity is more than 80% for all of the media.The experimental results show that a two-stage SBS pulse compression system has lower pump energy requirements,thus making it easier to achieve a compressed pulse waveform.The results also show that the shorter the phonon lifetime of the medium,the narrower the obtained compressed pulse width.

  3. Study on two-cell stimulated Brillouin scattering system with mixture medium

    Institute of Scientific and Technical Information of China (English)

    HASI; Wuliji

    2007-01-01

    In this paper,a method of choosing mixture medium in two-cell stimulated Brillouinscattering(SBS)system to improve the system performance is proposed.The Brillouin frequency shift(BFS)of mixture medium varies with the mixing ratio andthus the difference of the BFS between the two cells can be eliminated.The two-cellSBS system with acetone(C3H6O)in its generator cell and mixture liquid ofCCl4/C2Cl4 in its amplifier cell is investigated.The C3H6O has a high optical breakdown threshold and the mixture liquid of CCl4/C2Cl4 has a small absorption coeffi-cient and the same BFS as that of C3H6O when the volume fraction of CCl4 is 4%.Compared with two-cell SBS system with the same liquid(C2Cl4)or different liquid(C3H6O and C2Cl4)in generator and amplifier cell,the SBS system with mixture liq-uid(CCl4/C2Cl4)in amplifier cell and C3H6O in generator cell improves thepower-load,energy reflectivity(ER),phase conjugation(PC)fidelity and ER stabil-ity.

  4. Low power, chip-based stimulated Brillouin scattering microwave photonic filter with ultrahigh selectivity

    CERN Document Server

    Marpaung, David; Pagani, Mattia; Pant, Ravi; Choi, Duk-Yong; Luther-Davies, Barry; Madden, Steve J; Eggleton, Benjamin J

    2014-01-01

    Highly selective and reconfigurable microwave filters are of great importance in radio-frequency signal processing. Microwave photonic (MWP) filters are of particular interest, as they offer flexible reconfiguration and an order of magnitude higher frequency tuning range than electronic filters. However, all MWP filters to date have been limited by trade-offs between key parameters such as tuning range, resolution, and suppression. This problem is exacerbated in the case of integrated MWP filters, blocking the path to compact, high performance filters. Here we show the first chip-based MWP band-stop filter with ultra-high suppression, high resolution in the MHz range, and 0-30 GHz frequency tuning. This record performance was achieved using an ultra-low Brillouin gain from a compact photonic chip and a novel approach of optical resonance-assisted RF signal cancellation. The results point to new ways of creating energy-efficient and reconfigurable integrated MWP signal processors for wireless communications an...

  5. Particle spectra and efficiency in nonlinear relativistic shock acceleration: survey of scattering models

    CERN Document Server

    Ellison, Donald C; Bykov, Andrei M

    2015-01-01

    We include a general form for the scattering mean free path in a nonlinear Monte Carlo model of relativistic shock formation and Fermi acceleration. Particle-in-cell (PIC) simulations, as well as analytic work, suggest that relativistic shocks tend to produce short-scale, self-generated magnetic turbulence that leads to a scattering mean free path (mfp) with a stronger momentum dependence than the mfp ~ p dependence for Bohm diffusion. In unmagnetized shocks, this turbulence is strong enough to dominate the background magnetic field so the shock can be treated as parallel regardless of the initial magnetic field orientation, making application to gamma-ray bursts (GRBs), pulsar winds, Type Ibc supernovae, and extra-galactic radio sources more straightforward and realistic. In addition to changing the scale of the shock precursor, we show that, when nonlinear effects from efficient Fermi acceleration are taken into account, the momentum dependence of the mfp has an important influence on the efficiency of cosm...

  6. Raman scattering spectra and crystal structure of acid potassium-lithium sulfate

    International Nuclear Information System (INIS)

    Paper presents the results of the comprehensive investigation into Raman scattering in potassium-lithium acid sulfate crystal. A model of crystal structure is suggested on the basis of the study data. The suggested consistent model of the crystalline structure of potassium-lithium acid sulfate crystal describes well both spectrum high-frequency and low-frequency sections and may be used to analyze models of phase transformation

  7. Resonance Light Scattering Spectra of Silver Thiocyanate System and its Application in Analysis

    Institute of Scientific and Technical Information of China (English)

    Chang Yin LU; Zhi Hui HAN; Sheng Yuan YANG

    2005-01-01

    A novel determination method of Ag+ was established. In acetic acid-sodium acetate buffer (pH 5.0) medium, Ag+ reacts with SCN- to form AgSCN in the presence of TritonX-100,which results in an increase of resonance light scattering (RLS) and giving a new RLS spectrum.The maximum RLS peak was at 585 nm. The enhancement of resonance light scattering at 585nm was proportional to the concentration of Ag+ ranging from 0.0045-4.00 μg mL-1 (r=0.9991),and the detection limit was 1.37 ng mL-1 with the recovery of 97.70%~104.80%.

  8. Intricate Plasma-Scattered Images and Spectra of Focused Femtosecond Laser Pulses

    Science.gov (United States)

    Ooi, C. H. Raymond; Talib, Md. Ridzuan

    2016-08-01

    We report on some interesting phenomena in the focusing and scattering of femtosecond laser pulses in free space that provide insights on intense laser plasma interactions. The scattered image in the far field is analyzed and the connection with the observed structure of the plasma at the focus is discussed. We explain the physical mechanisms behind the changes in the colorful and intricate image formed by scattering from the plasma for different compressions, as well as orientations of plano-convex lens. The laser power does not show significant effect on the images. The pulse repetition rate above 500 Hz can affect the image through slow dynamics The spectrum of each color in the image shows oscillatory peaks due to interference of delayed pulse that correlate with the plasma length. Spectral lines of atomic species are identified and new peaks are observed through the white light emitted by the plasma spot. We find that an Ar gas jet can brighten the white light of the plasma spot and produce high resolution spectral peaks. The intricate image is found to be extremely sensitive and this is useful for applications in sensing microscale objects.

  9. Intricate Plasma-Scattered Images and Spectra of Focused Femtosecond Laser Pulses.

    Science.gov (United States)

    Ooi, C H Raymond; Talib, Md Ridzuan

    2016-01-01

    We report on some interesting phenomena in the focusing and scattering of femtosecond laser pulses in free space that provide insights on intense laser plasma interactions. The scattered image in the far field is analyzed and the connection with the observed structure of the plasma at the focus is discussed. We explain the physical mechanisms behind the changes in the colorful and intricate image formed by scattering from the plasma for different compressions, as well as orientations of plano-convex lens. The laser power does not show significant effect on the images. The pulse repetition rate above 500 Hz can affect the image through slow dynamics The spectrum of each color in the image shows oscillatory peaks due to interference of delayed pulse that correlate with the plasma length. Spectral lines of atomic species are identified and new peaks are observed through the white light emitted by the plasma spot. We find that an Ar gas jet can brighten the white light of the plasma spot and produce high resolution spectral peaks. The intricate image is found to be extremely sensitive and this is useful for applications in sensing microscale objects. PMID:27571644

  10. Assessing the effect of a high-fat diet on rodents' adipose tissue using Brillouin and Raman spectroscopy

    Science.gov (United States)

    Troyanova-Wood, Maria; Gobbell, Cassidy; Meng, Zhaokai; Yakovlev, Vladislav V.

    2016-03-01

    The purpose of this study is to evaluate the effect of a high-lipid diet on elasticity of adipose tissue. We employed dual Raman/Brillouin microspectroscopy to analyze brown and white adipose tissues obtained from adult rats. The rats were divided into two groups, one of which received a high-fat feed, while the other served as a control. We hypothesized that the changes in the elasticity of adipose tissues between the two groups can be successfully assessed using Brillouin spectroscopy. We found that the brown adipose tissue possessed a lesser Brillouin shift than the white adipose within each group and that the elastic modulus of both adipose tissues increases in the high-fat diet group. The Raman spectra provided supplementary chemical information and indicated an increase in the lipid-to-protein ratio in the brown adipose, but not in the white adipose.

  11. 100km distributed temperature sensor based on coherent detection of spontaneous Brillouin back-scatter

    OpenAIRE

    Alahbabi, M.; CHO, Y. T.; Newson, T.P.

    2003-01-01

    We report the longest distributed temperature sensor based on microwave heterodyne detection of the frequency of the anti-Stokes Brillouin signal. At a sensing range of 100km, the temperature accuracy was 8degC, with a spatial resolution of 50m.

  12. Modeling of optical wireless scattering communication channels over broad spectra.

    Science.gov (United States)

    Liu, Weihao; Zou, Difan; Xu, Zhengyuan

    2015-03-01

    The air molecules and suspended aerosols help to build non-line-of-sight (NLOS) optical scattering communication links using carriers from near infrared to visible light and ultraviolet bands. This paper proposes channel models over such broad spectra. Wavelength dependent Rayleigh and Mie scattering and absorption coefficients of particles are analytically obtained first. They are applied to the ray tracing based Monte Carlo method, which models the photon scattering angle from the scatterer and propagation distance between two consecutive scatterers. Communication link path loss is studied under different operation conditions, including visibility, particle density, wavelength, and communication range. It is observed that optimum communication performances exist across the wavelength under specific atmospheric conditions. Infrared, visible light and ultraviolet bands show their respective features as conditions vary. PMID:26366662

  13. Quantification of plaque stiffness by Brillouin microscopy (Conference Presentation)

    Science.gov (United States)

    Antonacci, Giuseppe; Pedrigi, Ryan; Krams, Rob; Török, Peter

    2016-03-01

    Spontaneous Brillouin scattering is an inelastic scattering process arising from inherent thermal density fluctuations, or acoustic phonons, propagating in a medium. Over the last few years, Brillouin spectroscopy has shown great potential to become a reliable non-invasive diagnostic tool due to its unique capability of retrieving viscoelastic properties of materials such as strain and stiffness. The detection of the weak scattered light, in addition to the resolution of the Brillouin peaks (typically shifted by few GHz from the central peak) represent one of the greatest challenges in Brillouin. The recent development of high sensitivity CCD cameras has brought Brillouin spectroscopy from a point sampling technique to a new imaging modality. Furthermore, the application of Virtually Imaged Phased Array (VIPA) etalons has dramatically reduced insertion loss simultaneously allowing fast (myocardial infarction yet it is not currently possible to credibly assess its stiffness due to lack of suitable methods.

  14. SELECTION OF BRILLOUIN SHIFT DISCRIMINATOR FOR BRILLOUIN LIDAR

    Institute of Scientific and Technical Information of China (English)

    吴东; 刘智深

    2002-01-01

    For the measurement of vertical profiles of sound speed in the sea using laser excited Brillouin scattering, a high-resolution measurement of Brillouin frequency shift is required. In this work, a molecular absorption cell was selec ted as the frequency shift discriminator and several kinds of absorption gases were tri ed. It was found that the strong line (#1095) of 127I2 at 18783.3297 cm-1 and two absorption lines of 129I2 located at the two sides of the #1095 line of 127 I2 could be used as frequency shift discriminator to detect the changes of the Brillouin frequency s hift. This selection is the best one within the range from 532.0131 nm to 532.5154 nm. But it is not perfect and there is a lot of work to do before its practical application.

  15. SELECTION OF BRILLOUIN SHIFT DISCRIMINATOR FOR BRILLOUIN LIDAR

    Institute of Scientific and Technical Information of China (English)

    吴东; 刘智深

    2002-01-01

    For the measurement of vertical profiles of sound speed in the sea using laser excited Brillouin scattering, a high-resolution measurement of Brillouin frequency shift is required. In this work, a molecular absorption cell was selected as the frequency shift discriminator and several kinds of absorption gases were tried. It was found that the strong line ( # 1095) of 127 I2 at 18783. 3297 cm-1 and two absorption lines of 129 I2 located at the two sides of the # 1095 line of 127 I2 could be used as frequency shift discriminator to detect the changes of the Brillouin frequency shift. This selection is the best one within the range from 532.0131 run to 532.5154 nm. But it is not perfect and there is a lot of work to do before its practical application.

  16. Imaging of Keratoconic and normal human cornea with a Brillouin imaging system (Conference Presentation)

    Science.gov (United States)

    Besner, Sebastien; Shao, Peng; Scarcelli, Giuliano; Pineda, Roberto; Yun, Seok-Hyun (Andy)

    2016-03-01

    Keratoconus is a degenerative disorder of the eye characterized by human cornea thinning and morphological change to a more conical shape. Current diagnosis of this disease relies on topographic imaging of the cornea. Early and differential diagnosis is difficult. In keratoconus, mechanical properties are found to be compromised. A clinically available invasive technique capable of measuring the mechanical properties of the cornea is of significant importance for understanding the mechanism of keratoconus development and improve detection and intervention in keratoconus. The capability of Brillouin imaging to detect local longitudinal modulus in human cornea has been demonstrated previously. We report our non-contact, non-invasive, clinically viable Brillouin imaging system engineered to evaluate mechanical properties human cornea in vivo. The system takes advantage of a highly dispersive 2-stage virtually imaged phased array (VIPA) to detect weak Brillouin scattering signal from biological samples. With a 1.5-mW light beam from a 780-nm single-wavelength laser source, the system is able to detect Brillouin frequency shift of a single point in human cornea less than 0.3 second, at a 5μm/30μm lateral/axial resolution. Sensitivity of the system was quantified to be ~ 10 MHz. A-scans at different sample locations on a human cornea with a motorized human interface. We imaged both normal and keratoconic human corneas with this system. Whereas no significantly difference were observed outside keratocnic cones compared with normal cornea, a highly statistically significantly decrease was found in the cone regions.

  17. Particle spectra and efficiency in nonlinear relativistic shock acceleration - survey of scattering models

    Science.gov (United States)

    Ellison, Donald C.; Warren, Donald C.; Bykov, Andrei M.

    2016-03-01

    We include a general form for the scattering mean free path, λmfp(p), in a nonlinear Monte Carlo model of relativistic shock formation and Fermi acceleration. Particle-in-cell simulations, as well as analytic work, suggest that relativistic shocks tend to produce short-scale, self-generated magnetic turbulence that leads to a scattering mean free path with a stronger momentum dependence than the λmfp ∝ p dependence for Bohm diffusion. In unmagnetized shocks, this turbulence is strong enough to dominate the background magnetic field so the shock can be treated as parallel regardless of the initial magnetic field orientation, making application to γ-ray bursts, pulsar winds, type Ibc supernovae, and extragalactic radio sources more straightforward and realistic. In addition to changing the scale of the shock precursor, we show that, when nonlinear effects from efficient Fermi acceleration are taken into account, the momentum dependence of λmfp(p) has an important influence on the efficiency of cosmic ray production as well as the accelerated particle spectral shape. These effects are absent in non-relativistic shocks and do not appear in relativistic shock models unless nonlinear effects are self-consistently described. We show, for limited examples, how the changes in Fermi acceleration translate to changes in the intensity and spectral shape of γ-ray emission from proton-proton interactions and pion-decay radiation.

  18. Cooperative stimulated Brillouin scattering driven by overlapping, large spot laser beams

    Science.gov (United States)

    Kruer, William; Kirkwood, Robert; Michel, Pierre; Turnbull, David

    2013-10-01

    In NIF hohlraums, large regions of plasma are irradiated with intense overlapping and large spot laser beams. In this regime, cooperative excitation of stimulated scattering can become a significant effect. Indeed, the potential importance of cooperative scattering has already been illustrated in calculations of cross beam energy transfer, where many crossing laser beams enhance the energy of another beam- a form of (generally nonresonant) cooperative SBS in the forward direction. Similarly, cooperative interactions are thought to play some role in scattering in the backward direction. Here we consider an interesting special case in which all the beams in a cone resonantly drive an ion sound wave along the hohlraum axis. This results in laser light being scattered backward along the cone. The frequency of this scattered light differs from that of the light directly backscattered by each beam, although there may be cross talk if the frequency of the backscattered light is sufficiently broad. A simple theory is presented, and some experiments to isolate and characterize cooperative scattering are discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  19. Measurement error analysis of Brillouin lidar system using F-P etalon and ICCD

    Science.gov (United States)

    Yao, Yuan; Niu, Qunjie; Liang, Kun

    2016-09-01

    Brillouin lidar system using Fabry-Pérot (F-P) etalon and Intensified Charge Coupled Device (ICCD) is capable of real time remote measuring of properties like temperature of seawater. The measurement accuracy is determined by two key parameters, Brillouin frequency shift and Brillouin linewidth. Three major errors, namely the laser frequency instability, the calibration error of F-P etalon and the random shot noise are discussed. Theoretical analysis combined with simulation results showed that the laser and F-P etalon will cause about 4 MHz error to both Brillouin shift and linewidth, and random noise bring more error to linewidth than frequency shift. A comprehensive and comparative analysis of the overall errors under various conditions proved that colder ocean(10 °C) is more accurately measured with Brillouin linewidth, and warmer ocean (30 °C) is better measured with Brillouin shift.

  20. Correlation-based continuous-wave technique for optical fiber distributed strain measurement using Brillouin scattering (Invited Paper)

    Science.gov (United States)

    Hotate, Kazuo

    2005-05-01

    We have been developing "fiber optic nerve systems" for "smart structures and smart materials", in which an optical fiber acts as sensor to measure distribution of strain along it. The original technology, "Brillouin Optical Correlation Domain Analysis: BOCDA" has been proposed and developed to analyze the distributed strain along the fiber by use of synthesis of correlation characteristics of continuous lightwave. Adopting this technology, "fiber optic nerve systems" with quite a high spatial resolution and measurement speed, have been established.

  1. Atherosclerotic plaque detection by confocal Brillouin and Raman microscopies

    Science.gov (United States)

    Meng, Zhaokai; Basagaoglu, Berkay; Yakovlev, Vladislav V.

    2015-02-01

    Atherosclerosis, the development of intraluminal plaque, is a fundamental pathology of cardiovascular system and remains the leading cause of morbidity and mortality worldwide. Biomechanical in nature, plaque rupture occurs when the mechanical properties of the plaque, related to the morphology and viscoelastic properties, are compromised, resulting in intraluminal thrombosis and reduction of coronary blood flow. In this report, we describe the first simultaneous application of confocal Brillouin and Raman microscopies to ex-vivo aortic wall samples. Such a non-invasive, high specific approach allows revealing a direct relationship between the biochemical and mechanical properties of atherosclerotic tissue.

  2. Distinctive features of Q-switching in optical cavity by means of Mandel'shtam-Brillouin stimulated-scattering mirror

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyev, M.V.; Leshchev, A.A.; Semenov, P.M.; Sidorovich, V.G.

    1982-02-01

    An earlier experiment with a laser and an optical cavity revealed triggering of a monopulse by a light beam moving within a very narrow channel through the resonator cavity formed by a flat mirror and a Mandel'shtam-Brillouin stimulated-scattering (MBSS) mirror. This effect was subsequently utilized for Q-switching in such a cavity with neodymium glass as active medium inside, by means of an MBSS mirror placed before the waveguide. The radiation spectrum and the energy distribution were measured in these experiments, a four-wave MBSS mirror having been found to give exact wavefront reversal. It thus appears feasible to improve both the spatial coherence and the directivity of laser radiation by forming the resonator with a flat mirror and an MBSS mirror. The authors thank Yu. N. Denisyuk for support of this study and N.A. Sventsitskiy for helpful suggestions. 10 references, 6 figures.

  3. Surface Brillouin scattering measurement of the elastic constants of single crystal InAs{sub 0.91}Sb{sub 0.09}

    Energy Technology Data Exchange (ETDEWEB)

    Kotane, L M; Comins, J D; Every, A G [Materials Physics Research Institute, School of Physics, University of the Witwatersrand, Johannesburg, Wits 2050 (South Africa); Botha, J R, E-mail: Lesias.Kotane@wits.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2011-01-01

    Surface Brillouin scattering of light has been used to measure the angular dependence of the Rayleigh surface acoustic wave (SAW), pseudo surface acoustic wave (PSAW) and longitudinal lateral wave (LLW) speeds in a (100)-oriented single crystal of the ternary semiconductor alloy InAs{sub 0.91}Sb{sub 0.09}. The wave speed measurements have been used to determine the room temperature values of the elastic constants C{sub 11}, C{sub 12} and C{sub 44} of the alloy. A simple and robust fitting procedure has been implemented for recovering the elastic constants, in which the merit function is constructed from explicit secular functions that determine the surface and lateral wave speeds in the [001] and [011] crystallographic directions. In the fitting, relatively larger weighting factors have been assigned to the SAW and PSAW data because of the greater precision with which the surface modes can be measured as compared with the lateral wave.

  4. Surface Brillouin scattering measurement of the elastic constants of single crystal InAs0.91Sb0.09

    International Nuclear Information System (INIS)

    Surface Brillouin scattering of light has been used to measure the angular dependence of the Rayleigh surface acoustic wave (SAW), pseudo surface acoustic wave (PSAW) and longitudinal lateral wave (LLW) speeds in a (100)-oriented single crystal of the ternary semiconductor alloy InAs0.91Sb0.09. The wave speed measurements have been used to determine the room temperature values of the elastic constants C11, C12 and C44 of the alloy. A simple and robust fitting procedure has been implemented for recovering the elastic constants, in which the merit function is constructed from explicit secular functions that determine the surface and lateral wave speeds in the [001] and [011] crystallographic directions. In the fitting, relatively larger weighting factors have been assigned to the SAW and PSAW data because of the greater precision with which the surface modes can be measured as compared with the lateral wave.

  5. High-average-power green laser using Nd:YAG amplifier with stimulated Brillouin scattering phase-conjugate pulse-cleaning mirror.

    Science.gov (United States)

    Tsubakimoto, Koji; Yoshida, Hidetsugu; Miyanaga, Noriaki

    2016-06-13

    We present a high-average-power green laser based on second harmonic conversion of a laser diode-pumped master oscillator Nd:YAG power amplifier system. The power amplifier chain includes a stimulated Brillouin scattering (SBS) cell that was used a phase-conjugate mirror to double-pass scheme. That suppresses the thermal phase distortion and compresses the pulse duration. The fundamental beam output power was 670 W with a pulse width of 7.9 ns. A second harmonic power of 335 W with a 4.8-ns pulse width and 80-mJ pulse energy was produced using a LiB3O5 (LBO) crystal. PMID:27410277

  6. Highly Repetitive Laser Inertial fusion driver with Tiled Coherent Beam Combination Laser using Stimulated Brillouin Scattering Phase Conjugation Mirrors

    International Nuclear Information System (INIS)

    Full text: In these days, the energy problem is serious in the world. It is necessary to develop a new source of the sustainable energy. In these sustainable energy sources, fusion energy is the most promised energy source. Especially, the laser inertial fusion energy is easy to maintain and easy to increase its scale. However, there are 3 hot problems to achieve the laser inertial fusion energy. To achieve the LIFE, it is necessary to develop 2.5 kJ/10 ns at 10 Hz laser. The Second problem is target injection with high repetition rate and high accuracy. We need to inject the fuel target to the centre of a chamber with accuracy to 20 μm after the fusion reaction. The third problem is the target window coating due to debris from the target implosion. The first and the second problems can be resolved simply by coherent beam combination laser using Stimulated Brillouin Scattering Phase Conjugation Mirrors (SBS-PCM). The 4-beam combination system is built to prove its feasibility to laser inertial fusion energy driver. The input energy of the each sub-beam is 1.032 ± 0.027 mJ, and the output energy of sub-beam is 402.3 ± 1.21 mJ. The standard deviations of the phase differences between the reference beam and other beams were measured to be less than λ/13, during 2,500 shots (250 s), and we will get it better than λ/20 soon. The coherent beam combination using SBS-PCM has additional advantages in LIFE reactor system. In the fusion reaction, target injection is one of the serious problems. The repetition rate of the target injection is ∼ 10 Hz, and the target speed is around 400 m/s. We need the accuracy of target position to 20 μm. Because of the turbulent flow after the prior fusion reaction, it is impossible to inject the target with the accuracy to more than 20 μm. This method can give the accuracy to less than 1 μm even when the turbulence exists in the reactor chamber. In this paper, the authors introduce the tiled coherent beam combining laser using SBS

  7. Simulations and analysis of the Raman scattering and differential Raman scattering/Raman optical activity (ROA) spectra of amino acids, peptides and proteins in aqueous solution

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Nieminen, R. M.; Bohr, Jakob

    2000-01-01

    The Raman and Raman optical activity (ROA) spectra of amino acids and small peptides in aqueous solution have been simulated by density functional theory and restricted Hartree/Fock methods. The treatment of the aqueous environment in treated in two ways. The water molecules in the first hydration...... shell which strongly interact with the molecule are treated explicitly while the waters in the bulk are treated by a continuum model. The structures are optimized and the harmonic force elds are calculated. The derivatives needed to simulate the Raman and ROA intensities are calculated from first...... principles. The simulated Raman and ROA spectra have been compared to recently meassured spectra on amino acids and peptides. The simulations and understanding from them are used to interpret the Raman and ROA spectra of proteins. A comparison to vibrational absorption (VA) and vibrational circular dichroism...

  8. Fine structure of inelastic electron scattering cross-section spectra for MN

    Science.gov (United States)

    Parshin, A. S.; Igumenov, A. Yu; Mikhlin, Yu L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2016-04-01

    The comparative analysis of the reflection electron energy loss spectra and the inelastic electron scattering cross-section spectra for Mn was carried out. It is shown that inelastic electron scattering cross-section spectra have certain advantages in the study of the interaction of electrons with the substance as compared to the electron energy loss spectra. The inelastic electron scattering cross section spectra fine structure was analysed by fitting the experimental spectra using the 3 parameters Lorentzian-type formula of Tougaard. This method was used for the quantitative analysis of the contributions of various loss processes in the inelastic electron scattering cross section spectra, determination of the loss peaks energies and origin.

  9. Phase-locking and Pulse Generation in Multi-Frequency Brillouin Oscillator via Four Wave Mixing

    Science.gov (United States)

    Büttner, Thomas F. S.; Kabakova, Irina V.; Hudson, Darren D.; Pant, Ravi; Poulton, Christopher G.; Judge, Alexander C.; Eggleton, Benjamin J.

    2014-05-01

    There is an increasing demand for pulsed all-fibre lasers with gigahertz repetition rates for applications in telecommunications and metrology. The repetition rate of conventional passively mode-locked fibre lasers is fundamentally linked to the laser cavity length and is therefore typically ~10-100 MHz, which is orders of magnitude lower than required. Cascading stimulated Brillouin scattering (SBS) in nonlinear resonators, however, enables the formation of Brillouin frequency combs (BFCs) with GHz line spacing, which is determined by the acoustic properties of the medium and is independent of the resonator length. Phase-locking of such combs therefore holds a promise to achieve gigahertz repetition rate lasers. The interplay of SBS and Kerr-nonlinear four-wave mixing (FWM) in nonlinear resonators has been previously investigated, yet the phase relationship of the waves has not been considered. Here, we present for the first time experimental and numerical results that demonstrate phase-locking of BFCs generated in a nonlinear waveguide cavity. Using real-time measurements we demonstrate stable 40 ps pulse trains with 8 GHz repetition rate based on a chalcogenide fibre cavity, without the aid of any additional phase-locking element. Detailed numerical modelling, which is in agreement with the experimental results, highlight the essential role of FWM in phase-locking of the BFC.

  10. SPECT Compton-scattering correction by analysis of energy spectra.

    Science.gov (United States)

    Koral, K F; Wang, X Q; Rogers, W L; Clinthorne, N H; Wang, X H

    1988-02-01

    The hypothesis that energy spectra at individual spatial locations in single photon emission computed tomographic projection images can be analyzed to separate the Compton-scattered component from the unscattered component is tested indirectly. An axially symmetric phantom consisting of a cylinder with a sphere is imaged with either the cylinder or the sphere containing 99mTc. An iterative peak-erosion algorithm and a fitting algorithm are given and employed to analyze the acquired spectra. Adequate separation into an unscattered component and a Compton-scattered component is judged on the basis of filtered-backprojection reconstruction of corrected projections. In the reconstructions, attenuation correction is based on the known geometry and the total attenuation cross section for water. An independent test of the accuracy of separation is not made. For both algorithms, reconstructed slices for the cold-sphere, hot-surround phantom have the correct shape as confirmed by simulation results that take into account the measured dependence of system resolution on depth. For the inverse phantom, a hot sphere in a cold surround, quantitative results with the fitting algorithm are accurate but with a particular number of iterations of the erosion algorithm are less good. (A greater number of iterations would improve the 26% error with the algorithm, however.) These preliminary results encourage us to believe that a method for correcting for Compton-scattering in a wide variety of objects can be found, thus helping to achieve quantitative SPECT. PMID:3258023

  11. Sp eed of sound measurement from sp ontaneous Brillouin scattering%利用自发布里渊散射测量液体声速∗

    Institute of Scientific and Technical Information of China (English)

    张颖; 王升; 郑雄; 何茂刚

    2015-01-01

    In order to overcome the problem of poor accuracy of resonant interferometer method in the measurement of thermodynamic sound speed and hypersound speed of liquids an experimental setup for measuring the sound speed of liquids is established based on the principle of spontaneous Brillouin light scattering. A Fabry-Perot interferometer is used to filter the scattered light and a data acquisition card as well as a photon counting head is used to detect and analyze the scattered light, then a data acquisition and analysis method of scattered light is presented. This method overcomes the limitation of the signal distortion in conventional Brillouin light scattering and increases the measuring accuracy of the sound speed of liquids remarkably. The sound speed of saturated liquid CCl4 is measured in the frequency range of 308.6 to 906.2 MHz at 298.15 K. Results agree well with the data reported in the literature, and show that the experimental method is feasible. In addition, the method for measuring the ultrasonic speed is proposed by adding several free spectral ranges to the measured Brillouin frenquency-shift. The ultrasonic speed of CCl4 measured is in the frequency range of 5406.1—5521.0 MHz. It is shown that the thermodynamic sound speed does not change with the sound frequency, while the hypersound speed increases with the increase of sound frequency and it is much greater than the thermodynamic sound speed, which proves the dispersion phenomena of CCl4.%为了克服共振干涉法在液体的热力学声速和高频声速测量方面精度不高的问题,本文建立了一种基于自发布里渊散射原理的测定液体声速的实验装置.利用法布里-珀罗干涉仪对散射光进行扫描滤波,数据采集卡结合光子计数器对散射光进行探测,设计了一种散射光信息采集分析方法.该实验方法有效的解决了传统布里渊散射方法中信号失真的问题,显著地提升了液体声速测量精度.对308.6—906

  12. Electron scattering from Xe: the relation between the differential elastic cross section and shape and intensity of the energy loss spectra

    Energy Technology Data Exchange (ETDEWEB)

    Vos, Maarten, E-mail: maarten.vos@anu.edu.a [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra, ACT (Australia)

    2010-11-14

    The measurement of the energy loss spectra of energetic electrons scattered from Xe over large angles is reported. The incoming energy was chosen between 600 eV and 1550 eV. The calculated Xe elastic scattering cross section has a sharp minimum for 750 eV electrons near 135{sup 0}. This minimum is confirmed by studying a Xe-H{sub 2} mixture and separating their elastic peak based on the recoil effect. The energy loss part of the Xe spectra is rich in structure. Surprisingly the shape and intensity (relative to the elastic peak) changes dramatically if one approaches the scattering conditions for which the elastic cross section has a minimum. These observations are rationalized by describing the inelastic intensity semi-classically, as a consequence of a two-step process occurring at the same atom involving scattering from the nucleus and an electronic excitation. The change in shape of the loss spectra is attributed to a large increase in relative intensity of the dipole-forbidden transitions near sharp minima in the elastic cross section.

  13. Multiple-scattering calculations of x-ray-absorption spectra

    International Nuclear Information System (INIS)

    A high-order multiple-scattering (MS) approach to the calculation of polarized x-ray-absorption spectra, which includes both x-ray-absorption fine structure and x-ray-absorption near-edge structure, is presented. Efficient calculations in arbitrary systems are carried out by using a curved-wave MS path formalism that ignores negligible paths, and has an energy-dependent self-energy and MS Debye-Waller factors. Embedded-atom background absorption calculations on an absolute energy scale are included. The theory is illustrated for metallic Cu, Cd, and Pt. For these cases the MS expansion is found to converge to within typical experimental accuracy, both to experiment and to full MS theories (e.g., band structure), by using only a few dozen important paths, which are primarily single-scattering, focusing, linear, and triangular

  14. Large-scale segmentation errors in optical gratings and their unique effect onto optical scattering spectra

    Science.gov (United States)

    Heusinger, Martin; Flügel-Paul, Thomas; Zeitner, Uwe-Detlef

    2016-08-01

    In this paper, we analyze the influence of large-scale segmentation errors in the morphology of high-performance optical gratings. It is thus assumed that the optical grating under consideration (typical lateral extends S are 10-1000 mm) can be spatially decomposed into a great many but unique sub-segments (≪ S; typical extends are 10-100 μm). Any violation of the perfect periodicity will result in the generation of stray light, especially Rowland ghosts, which radiate into a small angular region around the grating's diffraction orders. In this paper, we focus on three different kinds of segmentation errors. On the one hand, there are statistic as well as deterministic alignment errors between otherwise perfect sub-segments. On the other hand, we analyze the effect of chirping of geometrical parameters, i.e., the groove width, within every sub-segment. Most importantly, we find that the particular type of imperfection results in a unique characteristic of the according stray light spectrum which thus acts as a fingerprint. We come to this conclusion on three different ways. First, we rely on a simple theoretical model that is based on scalar diffraction theory. Second, we have performed rigorous numerical simulations for a high aspect ratio purely dielectric spectrometer grating (period = {667} nm). Third, the very same grating was then fabricated by e-beam lithography and its stray light spectrum was measured with a purposely designed optical setup. Eventually, all different routes to analyze the problem turn out to be in very good agreement, and we are confident that stray light measurements can be used as an important tool in the detection of fabrication imperfections.

  15. Analysis of stimulated Raman backscatter and stimulated Brillouin backscatter in experiments performed on SG-III prototype facility with a spectral analysis code

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Liang; Zhao, Yiqing; Hu, Xiaoyan; Zou, Shiyang [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Yang, Dong; Wang, Feng; Peng, Xiaoshi; Li, Zhichao; Li, Sanwei; Xu, Tao; Wei, Huiyue [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Liu, Zhanjun; Zheng, Chunyang, E-mail: zheng-chunyang@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Key Laboratory of HEDP of the Ministry of Education, CAPT, Peking University, Beijing 100871 (China)

    2014-07-15

    Experiments about the observations of stimulated Raman backscatter (SRS) and stimulated Brillouin backscatter (SBS) in Hohlraum were performed on Shenguang-III (SG-III) prototype facility for the first time in 2011. In this paper, relevant experimental results are analyzed for the first time with a one-dimension spectral analysis code, which is developed to study the coexistent process of SRS and SBS in Hohlraum plasma condition. Spectral features of the backscattered light are discussed with different plasma parameters. In the case of empty Hohlraum experiments, simulation results indicate that SBS, which grows fast at the energy deposition region near the Hohlraum wall, is the dominant instability process. The time resolved spectra of SRS and SBS are numerically obtained, which agree with the experimental observations. For the gas-filled Hohlraum experiments, simulation results show that SBS grows fastest in Au plasma and amplifies convectively in C{sub 5}H{sub 12} gas, whereas SRS mainly grows in the high density region of the C{sub 5}H{sub 12} gas. Gain spectra and the spectra of backscattered light are simulated along the ray path, which clearly show the location where the intensity of scattered light with a certain wavelength increases. This work is helpful to comprehend the observed spectral features of SRS and SBS. The experiments and relevant analysis provide references for the ignition target design in future.

  16. Direct optical transitions at K- and H-point of Brillouin zone in bulk MoS2, MoSe2, WS2, and WSe2

    Science.gov (United States)

    Kopaczek, J.; Polak, M. P.; Scharoch, P.; Wu, K.; Chen, B.; Tongay, S.; Kudrawiec, R.

    2016-06-01

    Modulated reflectance (contactless electroreflectance (CER), photoreflectance (PR), and piezoreflectance (PzR)) has been applied to study direct optical transitions in bulk MoS2, MoSe2, WS2, and WSe2. In order to interpret optical transitions observed in CER, PR, and PzR spectra, the electronic band structure for the four crystals has been calculated from the first principles within the density functional theory for various points of Brillouin zone including K and H points. It is clearly shown that the electronic band structure at H point of Brillouin zone is very symmetric and similar to the electronic band structure at K point, and therefore, direct optical transitions at H point should be expected in modulated reflectance spectra besides the direct optical transitions at the K point of Brillouin zone. This prediction is confirmed by experimental studies of the electronic band structure of MoS2, MoSe2, WS2, and WSe2 crystals by CER, PR, and PzR spectroscopy, i.e., techniques which are very sensitive to critical points of Brillouin zone. For the four crystals besides the A transition at K point, an AH transition at H point has been observed in CER, PR, and PzR spectra a few tens of meV above the A transition. The spectral difference between A and AH transition has been found to be in a very good agreement with theoretical predictions. The second transition at the H point of Brillouin zone (BH transition) overlaps spectrally with the B transition at K point because of small energy differences in the valence (conduction) band positions at H and K points. Therefore, an extra resonance which could be related to the BH transition is not resolved in modulated reflectance spectra at room temperature for the four crystals.

  17. Distributed fiber Brillouin strain sensing by correlation-based continuous-wave technique: cm-order spatial resolution and dynamic strain measurement

    Science.gov (United States)

    Hotate, Kazuo; Ong, Sean S.

    2002-09-01

    This paper describes a novel correlation-based technique for fiber optic distributed strain sensors using Brillouin scattering. Conventional Brillouin-based sensors utilize a pulsed-pump similar to that of OTDR and are capable of distributed strain sensing over large distances, but suffer an inherent spatial resolution limit of around 1m. In addition, unlike FBG-based strain sensors which are competent of measuring dynamic strain, the pulse-based Brillouin sensors have large measurement times of several minutes, making them inadequate for dynamic strain measurements. On the other hand, using the correlation-based continuous-wave technique, we have achieved static distributed strain measurements of up to 1cm spatial resolution, and dynamic strain measurements of up to 8.8Hz from a 5cm strained section.

  18. Thomson scattering and collisional ionization in the X-ray grating spectra of the recurrent nova U Scorpii

    Science.gov (United States)

    Orio, M.; Behar, E.; Gallagher, J.; Bianchini, A.; Chiosi, E.; Luna, G. J. M.; Nelson, T.; Rauch, T.; Schaefer, B. E.; Tofflemire, B.

    2013-02-01

    We present a Chandra observation of the recurrent nova U Scorpii, done with the High Resolution camera-S (HRC-S) detector and the Low Energy Transmission Grating (LETG) on day 18 after the observed visual maximum of 2010, and compare it with XMM-Newton observations obtained on days 23 and 35 after maximum. The total absorbed flux was in the range 2.2-2.6 × 10-11 erg cm-2 s-1, corresponding to unabsorbed luminosity 7-8.5 × 1036 ×(d/12 kpc)2 for N(H) = 2-2.7 × 1021 cm-2. On day 18, 70 per cent of the soft X-tray flux was in a continuum typical of a very hot white dwarf (WD) atmosphere, which accounted for about 80 per cent of the flux on days 23 and 35. In addition, all spectra display very broad emission lines, due to higher ionization stages at later times. With Chandra we observed apparent P Cygni profiles. We find that these peculiar profiles are not due to blueshifted absorption and redshifted emission in photoionized ejecta, like the optical P Cyg of novae, but they are rather a superposition of WD atmospheric absorption features reflected by the already discovered Thomson scattering corona, and emission lines due to collisional ionization in condensations in the ejecta. On days 23 and 35, the absorption components were no longer measurable, having lost the initial large blueshift that displaced them from the core of the broad emission lines. We interpret this as an indication that mass-loss ceased between day 18 and day 23. On day 35, the emission line spectrum became very complex, with several different components. Model atmospheres indicate that the WD atmospheric temperature was about 730 000 K on day 18 and reached 900 000-1000 000 K on day 35. This peak temperature is consistent with a WD mass of at least 1.3 M⊙.

  19. Molecular structure, natural bond analysis, vibrational and electronic spectra, surface enhanced Raman scattering and Mulliken atomic charges of the normal modes of [Mn(DDTC)2] complex.

    Science.gov (United States)

    Téllez S, Claudio A; Costa, Anilton C; Mondragón, M A; Ferreira, Glaucio B; Versiane, O; Rangel, J L; Lima, G Müller; Martin, A A

    2016-12-01

    Theoretical and experimental bands have been assigned for the Fourier Transform Infrared and Raman spectra of the bis(diethyldithiocarbamate)Mn(II) complex, [Mn(DDTC)2]. The calculations have been based on the DFT/B3LYP method, second derivative spectra and band deconvolution analysis. The UV-vis experimental spectra were measured in acetonitrile solution, and the calculated electronic spectrum was obtained using the TD/B3LYP method with 6-311G(d, p) basis set for all atoms. Charge transfer bands and those d-d spin forbidden were assigned in the UV-vis spectrum. The natural bond orbital analysis was carried out using the DFT/B3LYP method and the Mn(II) hybridization leading to the planar geometry of the framework was discussed. Surface enhanced Raman scattering (SERS) was also performed. Mulliken charges of the normal modes were obtained and related to the SERS enhanced bands. PMID:27344520

  20. Brillouin Lasing with a CaF_2 Whispering Gallery Mode Resonator

    CERN Document Server

    Grudinin, Ivan S; Maleki, Lute

    2008-01-01

    Stimulated Brillouin scattering with both pump and Stokes beams in resonance with whispering gallery modes of an ultra high Q CaF_2 resonator is demonstrated for the first time. The resonator is pumped with 1064 nm light and has a Brillouin lasing threshold of 3.5 microwatt. Potential applications include optical generation of microwaves and sensitive gyros.

  1. An unusual pulse compression of stimulated Brillouin scattering in water%水中受激布里渊散射脉冲的反常压缩

    Institute of Scientific and Technical Information of China (English)

    张磊; 李金增

    2014-01-01

    受激布里渊散射(SBS)具有脉冲压缩的特性,受激布里渊散射的脉冲宽度随着抽运能量的增大而变小,在水中可以达到几百皮秒的量级。本文在实验上观察到一种受激布里渊散射的脉冲宽度随抽运能量增大而变大的现象,这里称之为反常压缩。 SBS的脉冲反常压缩和脉冲压缩与抽运光的强弱会聚情况有关。利用数值模拟,模拟了强弱会聚情况下抽运光在水中的传输规律,强弱会聚情况的抽运光对受激布里渊散射形成的有效增益长度不同:抽运光强会聚时有效增益长度短,形成SBS脉冲宽度的反常压缩;弱会聚时有效增益长度长,也就是正常的SBS脉冲压缩。%Pulse compression is an important property of stimulated Brillouin scattering (SBS), and the SBS pulse duration becomes smaller with the increase of pump energy. An unusual pulse compression was investigated of the stimulated Brillouin scattering in water, it was found that the SBS pulse duration becomes larger as the pump energy increases. The pulse duration of SBS alters differently with the change of pump energy in strong focusing and weak focusing. Numerical simulation of pump light transmission in water cell has been made to explain the unusual pulse compression phenomena. Different real gain lengths in strong and weak focusing make different SBS pulse compression.

  2. Watching embryonic development in a new light: elasticity specific imaging with dual Brillouin/Raman microspectroscopy

    Science.gov (United States)

    Meng, Zhaokai; Hanson, Jessica A.; Yakovlev, Vladislav V.

    2016-03-01

    Mechanical properties of tissues play an important role in biological development. However, the current elasticity-specific imaging techniques are either destructive / invasive, or have a limited spatial and/or temporal resolution. Recently, we introduced Brillouin microscopy imaging as a local non-invasive probe of microscopic viscoelasticity in cells and tissues. In this study, by taking advantage of Brillouin spectroscopy, we imaged the viscoelasticity properties of different compartments of living zebrafish embryos, including yolk-sac, skin, spine and heart. Brillouin and Raman spectra were collected simultaneously at each location using a recently developed Brillouin/Raman microscope.

  3. X-ray scattering in X-ray fluorescence spectra with X-ray monochromatic, polarised excitation - Modelling, experiment, and Monte-Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hodoroaba, V.-D., E-mail: Dan.Hodoroaba@bam.de [BAM Federal Institute for Materials Research and Testing, Division 6.4 Surface Technologies, D-12200 Berlin (Germany); Radtke, M.; Reinholz, U.; Riesemeier, H. [BAM Federal Institute for Materials Research and Testing, Division 1.3 Structure Analysis, Polymer Analysis, D-12200 Berlin (Germany); Vincze, L. [Ghent University, Department of Analytical Chemistry, B-9000 Ghent (Belgium); Reuter, D. [BAM Federal Institute for Materials Research and Testing, Division 6.4 Surface Technologies, D-12200 Berlin (Germany)

    2011-07-01

    A systematic series of measurements has been carried out with monochromatic X-ray excitation with synchrotron radiation in order to check a physical model on X-ray scattering. The model has recently been successfully tested for the case of polychromatic, unpolarised excitation emitted by an X-ray tube. Our main purpose is the modelling of a physical background in X-ray fluorescence spectra, so that improved quantitative results can be achieved especially for strongly scattering specimens. The model includes single Rayleigh and Compton scattering in the specimen, the effect of bound electrons, the challenging Compton broadening and the polarisation degree. Representative specimens, measurement geometries and excitation energies have been selected with synchrotron monochromatic light at BAMline/BESSY II. Monte-Carlo simulations have been also carried out in order to evaluate the quality of the results achieved with the model.

  4. X-ray scattering in X-ray fluorescence spectra with X-ray monochromatic, polarised excitation - Modelling, experiment, and Monte-Carlo simulation

    International Nuclear Information System (INIS)

    A systematic series of measurements has been carried out with monochromatic X-ray excitation with synchrotron radiation in order to check a physical model on X-ray scattering. The model has recently been successfully tested for the case of polychromatic, unpolarised excitation emitted by an X-ray tube. Our main purpose is the modelling of a physical background in X-ray fluorescence spectra, so that improved quantitative results can be achieved especially for strongly scattering specimens. The model includes single Rayleigh and Compton scattering in the specimen, the effect of bound electrons, the challenging Compton broadening and the polarisation degree. Representative specimens, measurement geometries and excitation energies have been selected with synchrotron monochromatic light at BAMline/BESSY II. Monte-Carlo simulations have been also carried out in order to evaluate the quality of the results achieved with the model.

  5. Micro-focused Brillouin light scattering study of the magnetization dynamics driven by Spin Hall effect in a transversely magnetized NiFe nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Madami, M., E-mail: marco.madami@fisica.unipg.it; Carlotti, G. [Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Gubbiotti, G.; Tacchi, S. [Istituto Officina dei Materiali del CNR (CNR-IOM), Unità di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Moriyama, T.; Tanaka, K.; Ono, T. [Institute for Chemical Research, Kyoto University, Kyoto (Japan); Siracusano, G.; Finocchio, G. [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, Messina (Italy); Carpentieri, M. [Department of Electrical and Information Engineering, Politecnico of Bari, Bari (Italy)

    2015-05-07

    We employed micro-focused Brillouin light scattering to study the amplification of the thermal spin wave eigenmodes by means of a pure spin current, generated by the spin-Hall effect, in a transversely magnetized Pt(4 nm)/NiFe(4 nm)/SiO{sub 2}(5 nm) layered nanowire with lateral dimensions 500 × 2750 nm{sup 2}. The frequency and the cross section of both the center (fundamental) and the edge spin wave modes have been measured as a function of the intensity of the injected dc electric current. The frequency of both modes exhibits a clear redshift while their cross section is greatly enhanced on increasing the intensity of the injected dc. A threshold-like behavior is observed for a value of the injected dc of 2.8 mA. Interestingly, an additional mode, localized in the central part of the nanowire, appears at higher frequency on increasing the intensity of the injected dc above the threshold value. Micromagnetic simulations were used to quantitatively reproduce the experimental results and to investigate the complex non-linear dynamics induced by the spin-Hall effect, including the modification of the spatial profile of the spin wave modes and the appearance of the extra mode above the threshold.

  6. Scaled momentum spectra in deep inelastic scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences; University College London (United Kingdom); Max Planck Inst., Munich (Germany); Abt, I. [Max-Planck-Inst. fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

    2009-12-15

    Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb{sup -1}. Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The evolution of these spectra with the photon virtuality, Q{sup 2}, is described in the kinematic region 10and modified leading-log-approximation QCD calculations as well as predictions from Monte Carlo models are compared to the data. The results are also compared to e{sup +}e{sup -} annihilation data. The dependences of the pseudorapidity distribution of the particles on Q{sup 2} and on the energy in the {gamma}p system, W, are presented and interpreted in the context of the hypothesis of limiting fragmentation. (orig.)

  7. The Imaging Vector Magnetograph at Haleakala : III. Effects of Instrumental Scattered Light on Stokes Spectra

    Science.gov (United States)

    Labonte, Barry

    2004-06-01

    The scattering of light over the field of view of a solar spectropolarimeter affects all Stokes parameters. The magnetic field vector inferred from the Stokes spectra then has systematic error. The reason is that scattering affects polarized radiation as well as unpolarized. Accurate correction of the Stokes spectra from the Imaging Vector Magnetograph (IVM) of the Mees Solar Observatory illustrates the problem and the solutions.

  8. Resonantly scattering crystals and surfaces

    International Nuclear Information System (INIS)

    We examine coherence effects from forming a crystal of resonant scatterers by generalising the Fano model for autoionising resonances in electron scattering from atoms to a lattice of such scatterers. (We have in mind the case of neutron scattering from nuclei.) We solve this problem to yield two branches to the dispersion relation for the neutron in general and three when the resonance coincides with a Brillouin Zone boundary. The 'width' of the resonance is enhanced over the isolated nucleus, the best candidate for observation being the 2eV 185Re resonance near the Bragg condition. We use these results to calculate the reflection coefficient from a surface, revealing total external reflection near resonance. We discuss experimental feasibility in both the neutron and electron cases. (author)

  9. A Hamiltonian treatment of stimulated Brillouin scattering in nanoscale integrated waveguides

    CERN Document Server

    Sipe, J E

    2015-01-01

    We present a multimode Hamiltonian formulation for the problem of opto-acoustic interactions in optical waveguides. We establish a Hamiltonian representation of the acoustic field and then introduce a full system with a simple opto-acoustic coupling that includes both photoelastic/electrostrictive and radiation pressure/moving boundary effects. The Heisenberg equations of motion are used to obtain coupled mode equations for quantized envelope operators for the optical and acoustic fields. We show that the coupling coefficients obtained coincide with those established earlier, but our formalism provides a much simpler demonstration of the connection between radiation pressure and moving boundary effects than in previous work [C. Wolff et al, Physical Review A 92, 013836 (2015)].

  10. X-ray scattering in X-ray fluorescence spectra with X-ray tube excitation - Modelling, experiment, and Monte-Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hodoroaba, V.-D., E-mail: Dan.Hodoroaba@bam.d [BAM Federal Institute for Materials Research and Testing, Division VI.4 Surface Technologies, D-12200 Berlin (Germany); Radtke, M. [BAM Federal Institute for Materials Research and Testing, Division I.3 Structure Analysis, Polymer Analysis, D-12200 Berlin (Germany); Vincze, L. [Ghent University, Department of Analytical Chemistry, B-9000 Ghent (Belgium); Rackwitz, V.; Reuter, D. [BAM Federal Institute for Materials Research and Testing, Division VI.4 Surface Technologies, D-12200 Berlin (Germany)

    2010-12-15

    X-ray scattering may contribute significantly to the spectral background of X-ray fluorescence (XRF) spectra. Based on metrological measurements carried out with a scanning electron microscope (SEM) having attached a well characterised X-ray source (polychromatic X-ray tube) and a calibrated energy dispersive X-ray spectrometer (EDS) the accuracy of a physical model for X-ray scattering is systematically evaluated for representative samples. The knowledge of the X-ray spectrometer efficiency, but also of the spectrometer response functions makes it possible to define a physical spectral background of XRF spectra. Background subtraction relying on purely mathematical procedures is state-of-the-art. The results produced by the analytical model are at least as reliable as those obtained by Monte-Carlo simulations, even without considering the very challenging contribution of multiple scattering. Special attention has been paid to Compton broadening. Relevant applications of the implementation of the analytical model presented in this paper are the prediction of the limits of detection for particular cases or the determination of the transmission of X-ray polycapillary lenses.

  11. X-ray scattering in X-ray fluorescence spectra with X-ray tube excitation - Modelling, experiment, and Monte-Carlo simulation

    International Nuclear Information System (INIS)

    X-ray scattering may contribute significantly to the spectral background of X-ray fluorescence (XRF) spectra. Based on metrological measurements carried out with a scanning electron microscope (SEM) having attached a well characterised X-ray source (polychromatic X-ray tube) and a calibrated energy dispersive X-ray spectrometer (EDS) the accuracy of a physical model for X-ray scattering is systematically evaluated for representative samples. The knowledge of the X-ray spectrometer efficiency, but also of the spectrometer response functions makes it possible to define a physical spectral background of XRF spectra. Background subtraction relying on purely mathematical procedures is state-of-the-art. The results produced by the analytical model are at least as reliable as those obtained by Monte-Carlo simulations, even without considering the very challenging contribution of multiple scattering. Special attention has been paid to Compton broadening. Relevant applications of the implementation of the analytical model presented in this paper are the prediction of the limits of detection for particular cases or the determination of the transmission of X-ray polycapillary lenses.

  12. Amplification Effect on Rayleigh Scattering and SBS in 25 km Distributed Fiber Raman Amplifier

    Institute of Scientific and Technical Information of China (English)

    Hua-Ping Gong; Zai-Xuan Zhang

    2008-01-01

    The amplification effect on stimulated Brillouin scattering (SBS) and Rayleigh scattering in the backward pumped G652 fibers Raman amplifier have been researched. The signal source is a tunable narrow spectral bandwidth (<10 MHz) ECL laser and is pumped by the tunable power 1427.2 nm fiber Raman laser. The Rayleigh scattering lines are amplified by fiber Raman amplifier, and Stokes stimulated Brillouin scattering lines are amplified by fiber Raman amplifier and fiber BriUouin amplifier. The SBS lines total gain is a production of the gain of Raman and the gain of Brillouin amplifier. In experiment, the gain of SBS is about 42 dB and the saturation gain of 25 km G652 backward FRA is about 25 dB, so the gain of fiber Brillouin amplifier is about 17 dB.

  13. Accuracy limitations on Brillouin lidar measurements of temperature and sound speed in the ocean.

    Science.gov (United States)

    Fry, E S; Emery, Y; Quan, X; Katz, J W

    1997-09-20

    There are five mutually dependent variables relevant to Brillouin lidar measurements of temperature and sound speed in the ocean; they are (1) the Brillouin shift, (2) the sound speed, (3) the index of refraction, (4) the temperature, and (5) the salinity. We use three well-known relations to analyze rigorously the interdependence of these five variables. Clearly, a Brillouin shift measurement does not provide a stand-alone determination of temperature or sound speed; one more variable or one more relation must be known. The use of mean values of salinity that have been obtained by an analysis of a large set of historical in situ data is considered for this additional relation. PMID:18259560

  14. Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the H{sub α} line profiles and Thomson scattering spectra

    Energy Technology Data Exchange (ETDEWEB)

    Cvejić, M., E-mail: marko.cvejic@ipb.ac.rs, E-mail: krzysztof.dzierzega@uj.edu.pl [Institute of Physics, University of Belgrade, P.O. Box 68, 11080 Belgrade (Serbia); Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Dzierżęga, K., E-mail: marko.cvejic@ipb.ac.rs, E-mail: krzysztof.dzierzega@uj.edu.pl; Pięta, T. [M. Smoluchowski Institute of Physics, Jagellonian University, ul. Łojasiewicza 11, 30-348 Kraków (Poland)

    2015-07-13

    We have studied isothermal equilibrium in the laser-induced plasma from aluminum pellets in argon at pressure of 200 mbar by using a method which combines the standard laser Thomson scattering and analysis of the H{sub α}, Stark-broadened, line profiles. Plasma was created using 4.5 ns, 4 mJ pulses from a Nd:YAG laser at 1064 nm. While electron density and temperature were determined from the electron feature of Thomson scattering spectra, the heavy particle temperature was obtained from the H{sub α} full profile applying computer simulation including ion-dynamical effects. We have found strong imbalance between these two temperatures during entire plasma evolution which indicates its non-isothermal character. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium.

  15. Quantum-mechanical analysis of the intensity distribution in spectra of resonant Raman scattering spectra of aqueous solutions of tyrosine

    Science.gov (United States)

    Burova, T. G.; Shcherbakov, R. S.

    2016-05-01

    Quantum-mechanical calculations of the intensity distribution in the resonant Raman scattering spectra of aqueous solutions of tyrosine excited by laser radiation with wavelengths of 244, 229, 218, 200, and 193 nm, as well as in the nonresonant Raman scattering spectrum excited at a wavelength of 488 nm, are performed. Satisfactory agreement is achieved between the calculation results and the experimental data. It is shown that the changes in the intensity distribution observed in the spectra with a change in the excitation wavelength from 244 to 193 nm correlate with the determined changes in the contribution made by excited electronic states into the scattering tensor components. It is noted that it is necessary to take into account the Herzberg-Teller effect and that the number of excited electronic states taken into account considerably affects the calculated relative intensities of lines. The possibility of existence of several tyrosine conformers in aqueous solution at room temperature is shown.

  16. Stimulated Brillouin side-scattering of the beat wave excited by two counter-propagating X-mode lasers in magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Kanika; Sajal, Vivek, E-mail: vsajal@rediffmail.com; Kumar, Ravindra; Sharma, Navneet K. [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida 201307, Uttar Pradesh (India); Baliyan, Sweta [Department of Physics, Maitreyi College, University of Delhi, New Delhi 110021 (India)

    2015-06-15

    The stimulated Brillouin scattering (SBS) of nonresonant beat mode in the presence of static magnetic field is investigated in a plasma. Two counter-propagating lasers of frequencies (ω{sub 1} and ω{sub 2}) and wave vectors (k{sub 1} and k{sub 2}) drive a nonresonant space charge beat mode at the phase matching condition of frequency ω{sub 0}≈ω{sub 1}∼ω{sub 2} and wave number k{sup →}{sub 0}≈k{sup →}{sub 1}+k{sup →}{sub 2}. The driver wave parametrically excites a pair of ion acoustic wave (ω,k{sup →}) and a sideband electromagnetic wave (ω{sub 3},k{sup →}{sub 3}). The beat wave couples with the sideband electromagnetic wave to exert a nonlinear ponderomotive force at the frequency of ion acoustic wave. Density perturbations due to ion acoustic wave and ponderomotive force couple with the oscillatory motion of plasma electron due to velocity of beat wave to give rise to a nonlinear current (by feedback mechanism) responsible for the growth of sideband wave at resonance. The growth rate of SBS was reduced (from ∼10{sup 12}s{sup −1} to 10{sup 10}s{sup −1}) by applying a transverse static magnetic field ∼90 T. The present study can be useful for the excitation of fast plasma waves (for the purpose of electron acceleration) by two counter-propagating laser beams.

  17. Study of far-infrared reflection and Raman scattering spectra in reactive ion, etched ZnTe

    Institute of Scientific and Technical Information of China (English)

    吴森; 沈文忠; 小川博司; 郭其新

    2003-01-01

    Far-infrared reflection and Raman scattering measurements have been carried out on reactive ion,etched p-ZnTe samples.The averaged thickness of the surface damaged layer is found to be in the range of 1.0-1.5μm,and the,etch-induced defect density is in the order of 1018cm-3.The Raman intensity ratio between the second-order Raman peaks and the first-order longitudinal optical phonons reveals an increase trend with the radio frequency(rf)power.With the aid of related theories,we discuss the effects of the rf plasma power and the concentration of CH4/H2 on the damage,disorder,and the second-order Raman structures in p-ZnTe samples.

  18. Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis.

    Science.gov (United States)

    Głaz, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Haskopoulos, Anastasios; Maroulis, George

    2016-07-21

    A comprehensive study is presented of many aspects of the depolarized anisotropic collision induced (CI) component of light scattered by weakly bound compounds composed of a dihydrogen molecule and a rare gas (Rg) atom, H2-Rg. The work continues a series of earlier projects marking the revival of interest in linear light scattering following the development of new highly advanced tools of quantum chemistry and other theoretical, computational, and experimental means of spectral analyses. Sophisticated ab initio computing procedures are applied in order to obtain the anisotropic polarizability component's dependence on the H2-Rg geometry. These data are then used to evaluate the CI spectral lines for all types of Rg atoms ranging from He to Xe (Rn excluded). Evolution of the properties of CI spectra with growing polarizability/masses of the complexes studied is observed. Special attention is given to the heaviest, Kr and Xe based, scatterers. The influence of specific factors shaping the spectral lines (e.g., bound and metastable contribution, potential anisotropy) is discussed. Also the share of pressure broadened allowed rotational transitions in the overall spectral profile is taken into account and the extent to which it is separable from the pure CI contribution is discussed. We finish with a brief comparison between the obtained results and available experimental data. PMID:27448883

  19. Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis

    Science.gov (United States)

    Głaz, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Haskopoulos, Anastasios; Maroulis, George

    2016-07-01

    A comprehensive study is presented of many aspects of the depolarized anisotropic collision induced (CI) component of light scattered by weakly bound compounds composed of a dihydrogen molecule and a rare gas (Rg) atom, H2-Rg. The work continues a series of earlier projects marking the revival of interest in linear light scattering following the development of new highly advanced tools of quantum chemistry and other theoretical, computational, and experimental means of spectral analyses. Sophisticated ab initio computing procedures are applied in order to obtain the anisotropic polarizability component's dependence on the H2-Rg geometry. These data are then used to evaluate the CI spectral lines for all types of Rg atoms ranging from He to Xe (Rn excluded). Evolution of the properties of CI spectra with growing polarizability/masses of the complexes studied is observed. Special attention is given to the heaviest, Kr and Xe based, scatterers. The influence of specific factors shaping the spectral lines (e.g., bound and metastable contribution, potential anisotropy) is discussed. Also the share of pressure broadened allowed rotational transitions in the overall spectral profile is taken into account and the extent to which it is separable from the pure CI contribution is discussed. We finish with a brief comparison between the obtained results and available experimental data.

  20. Study on the absorption and fluorescence and resonance Rayleigh scattering spectra of Cu (Ⅱ)-fluoroquinolone chelates with erythrosine and their applications

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In pH 4.2-5.0 Britton-Robinson buffer solution medium, fluoroquinolone antibiotics (FLQs), such as ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OF), levofloxacin (LEV), lomefloxacin (LOM), and sparfloxacin (SPA), react with Cu (Ⅱ) to form chelate cations, which further bind with erythrosine to form the ion association complexes. They can result in the changes of the absorption spectra. Simultaneously, erythrosine fades obviously and the maximum fading wavelength is located at 526 nm. The fading reactions have high sensitivities. Thus, new spectrophotometries of determination for these drugs are developed. The ion-association reactions result in the quenching of fluorescence, which also have high sensitivities. The detection limits for six antibiotics are in the range of 7.1-12.2 μg·L-1. Furthermore, the reactions can result in the enhancement of resonance Rayleigh scattering (RRS). The maximum scattering peaks of six ion-association complexes are located at 566 nm, and there are two small RRS peaks at 333 nm and 287 nm. The detection limits for fluoroquinolone antibiotics are in the range of 1.70-3.10 μg·L-1 for RRS method. Among the above three methods, the RRS method has the highest sensitivity. In this work, we investigated the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reactions, and the properties of the analytical chemistry. In addition, the mechanism of reactions were discussed by density function theory (DFT) and AM1 methods.

  1. Effects of refraction on transmission spectra of gas giants: decrease of the Rayleigh scattering slope and breaking of retrieval degeneracies

    CERN Document Server

    Bétrémieux, Yan

    2015-01-01

    Detection of the signature of Rayleigh scattering in the transmission spectrum of an exoplanet is increasingly becoming the target of observational campaigns because the spectral slope of the Rayleigh continuum enables one to determine the scaleheight of its atmosphere in the absence of hazes. However, this is only true when one ignores the refractive effects of the exoplanet's atmosphere. I illustrate with a suite of simple isothermal clear Jovian H2-He atmosphere models with various abundances of water that refraction can decrease significantly the spectral slope of the Rayleigh continuum and that it becomes flat in the infrared. This mimics a surface, or an optically thick cloud deck, at much smaller pressures than one can probe in the non-refractive case. Although the relative impact of refraction on an exoplanet's transmission spectrum increases with decreasing atmospheric temperatures as well as increasing stellar temperature, it is still quite important from a retrieval's perspective even for a Jovian-...

  2. Amplification effect on SBS and Rayleigh scattering in the backward pumped distributed fiber Raman amplifier

    Institute of Scientific and Technical Information of China (English)

    Zaixuan Zhang; Huaping Gong

    2009-01-01

    The amplification effect on stimulated Brillouin scattering(SBS)and Rayleigh scattering in the backward pumped G652 fiber Raman amplifier(FRA)is studied.The pump source is a 1427.2-nm fiber Raman laser whose power is tunable between 0-1200 mW,and the signal source is a tunable narrow spectral bandwidth(<10 MHz)external cavity laser(ECL).The Rayleigh scattering lines are amplified by the FRA and Stokes SBS lines are amplified by the FRA and the fiber Brillouin amplifier.The total gain of SBS lines is the production of the gain of Raman amplifier and that of Brillouin amplifier.In experiment,the SBS gain is about 42 dB and the saturation gain of 25-km G652 backward FRA is about 25 dB,so the gain of fiber Brillouin amplifier is about 17 dB.

  3. Effects of the Interaction of Rifamycin SV with Serum Albumins on the Resonance Rayleigh Scattering Spectra and Their Analytical Application

    Institute of Scientific and Technical Information of China (English)

    YANG Ji-Dong; CAO Tuan-Wu; LIU Zhong-Fang; KONG Ling; LIU Shao-Pu

    2008-01-01

    In pH 4.5-4.8 Britton-Robinson buffer solution,rifamycin SV(i.e.rifamycin sodium)can react with serum albumin such as human selqlm albumin(HSA)and bovine serum albumin(BSA)to form macromolecular complexes by electrostatic attraction and hydrophobic force.As a result,the resonance Rayleigh scattering(RRS)of the drug was enhanced remarkably and the RRS peaks were at 374 and 552 nm.The enhancement of RRS(△I)is directly proportional to the concentration of HSA or BSA.The linear ranges and the detection limits are 0.03-6.0μg/mL and 9.0 ng/mL for HSA.and 0.01-8.0μg/mL and 2.0 ng/mL for BSA,respectively.In this work,a sensitive,selective,simple and fast methOd for the determination of trace amounts of serum albumin by RRS technique has been developed,which Was applied to the determination of serum albumin in the synthesized samples and human urine samples with satisfactory results.

  4. 受激布里渊散射光纤陀螺(SBS-FOG)中 传输光偏振稳定性的研究%Study on polarization stability of transmitting light for stimulated Brillouin scattering fiber optic gyros (SBS-FOG)

    Institute of Scientific and Technical Information of China (English)

    延凤平; 单英; 简水生

    2001-01-01

    研究了受激布里渊散射光纤陀螺(SBS-FOG)敏感环中,在保偏光纤熔接点处进行θ角的偏振主轴旋转后传输光的偏振稳定性。得出当θ=90°时,在敏感环中的传输光不仅具有最大偏振度,而且还使其中的两个本征偏振态(ESOP)达到稳定的结论。%The characteristics of the eigen state of polarization (ESOP) of the pump light and the stimulated Brillouin scattering light in the sensing coil were theoretically analyzed for the stimulated Brillouin scattering fiber optic gyros (SBS-FOG), and the conclusions about stability of the ESOP and polarization degree of the transmitting light were obtained.

  5. High-resolution long-reach distributed Brillouin sensing based on combined time-domain and correlation-domain analysis.

    Science.gov (United States)

    Elooz, David; Antman, Yair; Levanon, Nadav; Zadok, Avi

    2014-03-24

    A new scheme for distributed Brillouin sensing of strain and temperature in optical fibers is proposed, analyzed and demonstrated experimentally. The technique combines between time-domain and correlation-domain analysis. Both Brillouin pump and signal waves are repeatedly co-modulated by a relatively short, high-rate phase sequence, which introduces Brillouin interactions in a large number of discrete correlation peaks. In addition, the pump wave is also modulated by a single amplitude pulse, which leads to a temporal separation between the generation of different peaks. The Brillouin amplification of the signal wave at individual peak locations is resolved in the time domain. The technique provides the high spatial resolution and long range of unambiguous measurement offered by correlation-domain Brillouin analysis, together with reduced acquisition time through the simultaneous interrogation of a large number of resolution points. In addition, perfect Golomb codes are used in the phase modulation of the two waves instead of random sequences, in order to reduce noise due to residual, off-peak Brillouin interactions. The principle of the method is supported by extensive numerical simulations. Using the proposed scheme, the Brillouin gain spectrum is mapped experimentally along a 400 m-long fiber under test with a spatial resolution of 2 cm, or 20,000 resolution points, with only 127 scans per choice of frequency offset between pump and signal. Compared with corresponding phase-coded, Brillouin correlation domain analysis schemes with equal range and resolution, the acquisition time is reduced by a factor of over 150. A 5 cm-long hot spot, located towards the output end of the pump wave, is properly identified in the measurements. The method represents a significant advance towards practical high-resolution and long range Brillouin sensing systems.

  6. Incoherent scatter spectra from plasma of a 13-moment approximation distribution function

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The function and physical mechanism of heat flow and the viscous stress in the velocity distribution function expanded by Maxwellian distribution are presented. With the introduction of effective temperature Tf, incoherent scatter spectra from plasma for electromagnetic wave in arbitrary line of sight are given. The effect of asymmetry and anisotropy provided by heat flow and the viscous stress on power spectra is discussed. Radar spectra are calculated for different cases of electric field, direction, collision frequency and temperature. The effect of heat flow and the viscous stress on inversion results is analyzed. With a large electric field, the character of non-Maxwellian must be considered.

  7. Study on the absorption and fluorescence and resonance Rayleigh scattering spectra of Cu (II)-fluoroquinolone chelates with erythrosine and their applications

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In pH 4.2-5.0 Britton-Robinson buffer solution medium, fluoroquinolone antibiotics (FLQs), such as ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OF), levofloxacin (LEV), lomefloxacin (LOM), and sparfloxacin (SPA), react with Cu (II) to form chelate cations, which further bind with erythrosine to form the ion association complexes. They can result in the changes of the absorption spectra. Simultane- ously, erythrosine fades obviously and the maximum fading wavelength is located at 526 nm. The fad- ing reactions have high sensitivities. Thus, new spectrophotometries of determination for these drugs are developed. The ion-association reactions result in the quenching of fluorescence, which also have high sensitivities. The detection limits for six antibiotics are in the range of 7.1-12.2 μg·L?1. Furthermore, the reactions can result in the enhancement of resonance Rayleigh scattering (RRS). The maximum scattering peaks of six ion-association complexes are located at 566 nm, and there are two small RRS peaks at 333 nm and 287 nm. The detection limits for fluoroquinolone antibiotics are in the range of 1.70 -3.10 μg·L?1 for RRS method. Among the above three methods, the RRS method has the highest sen- sitivity. In this work, we investigated the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reactions, and the properties of the analytical chemistry. In addi- tion, the mechanism of reactions were discussed by density function theory (DFT) and AM1 methods.

  8. Multimode Brillouin spectrum in a long tapered birefringent photonic crystal fiber.

    Science.gov (United States)

    Tchahame, Joël Cabrel; Beugnot, Jean-Charles; Kudlinski, Alexandre; Sylvestre, Thibaut

    2015-09-15

    We investigate the stimulated Brillouin scattering (SBS) in a long tapered birefringent solid-core photonic crystal fiber (PCF) and compare our results with a similar but untapered PCF. It is shown that the taper generates a broadband and multipeaked Brillouin spectrum, while significantly increasing the threshold power. Furthermore, we observe that the strong fiber birefringence gives rise to a frequency shift of the Brillouin spectrum which increases along the fiber. Numerical simulations are also presented to account for the taper effect and the birefringence. Our findings open a new means to control or inhibit the SBS by tapering photonic crystal fibers. PMID:26371916

  9. A study of Brillouin scattering on relaxor based ferroelectric Pb[(Zn{sub 1/3}Nb{sub 2/3}){sub 0.91}Ti{sub 0.09}]O{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dohan; Kojima, Seiji [University of Tsukuba, Ibaraki (Japan); Ko, Jaehyeon [Hallym University, Chuncheon-Si (Korea, Republic of)

    2005-01-15

    Brillouin spectra of lead-based relaxor ferroelectric Pb[(Zn{sub 1/3}Nb{sub 2/3}){sub 0.91}Ti{sub 0.09}]O{sub 3} (PZN-9 %PT) single crystal have been studied to investigate the field-induced phase-transition anomalies. We could observe one distinct longitudinal acoustic mode (LA-mode) and one indistinct transverse acoustic mode (TA-mode). Generally, PZN-9 %PT crystals undergo two first-order phase transitions: cubic-tetragonal (C-T) and tetragonal-rhombohedral (T-R). The first-order phase transition of cubic-tetragonal seems to change into a second-order phase transition under an electric field along [010] direction, while the nature of the tetragonal-rhombohedral (or monoclinic) phase transition remains unchanged.

  10. Brillouin optical correlation domain reflectometry with lock-in detection scheme

    Science.gov (United States)

    Yao, Yuguo; Kishi, Masato; Hotate, Kazuo

    2016-07-01

    We propose a Brillouin optical correlation domain reflectometry (BOCDR) technique with a lock-in detection scheme in this paper. By designing a new system using the lock-in detection scheme and amplifying a small spontaneous Brillouin signal with a lock-in amplifier, a Brillouin scattering spectrum with a stable shape is obtained. By further introducing a periodical on/off phase modulation for chopping for lock-in detection, the undesired optical background spectrum is effectively reduced, and a 20 cm section with 7,000 µε strain is clearly measured.

  11. Brillouin spectroscopy as a new method of screening for increased CSF total protein during bacterial meningitis.

    Science.gov (United States)

    Steelman, Zachary; Meng, Zhaokai; Traverso, Andrew J; Yakovlev, Vladislav V

    2015-05-01

    Bacterial meningitis is a disease of pronounced clinical significance, especially in the developing world. Immediate treatment with antibiotics is essential, and no single test can provide a conclusive diagnosis. It is well established that elevated total protein in cerebrospinal fluid (CSF) is associated with bacterial meningitis. Brillouin spectroscopy is a widely used optical technique for noninvasive determination of the elastic moduli of materials. We found that elevated protein levels in CSF alter the fluid elasticity sufficiently to be measurable by Brillouin spectroscopy, with model healthy and diseased fluids distinguishable to marked significance (P = 0.014), which increases with sample concentration by dialysis. Typical raw output of a 2-stage VIPA Brillouin spectrometer: inelastically scattered Brillouin peaks (arrows) and elastically scattered incident radiation (center cross).

  12. Distributed fiber Brillouin strain and temperature sensor with centimeter spatial resolution by coherent probe-pump technique

    Science.gov (United States)

    Zou, Lufan; Bao, Xiaoyi; Wan, Yidun; Ravet, Fabien; Chen, Liang

    2005-05-01

    We present a sensing principle of the distributed fiber Brillouin strain and temperature sensor by coherent probe-pump technique that offers a new method to achieve centimeter spatial resolution with high frequency resolution. A combination of continuous wave (cw) and pulse source as the probe (Stokes) beam and cw laser as the pump beam have resulted in stronger Brillouin interaction of Stokes and pump inside the pulse-length in the form of cw-pump and pulse-pump interactions. We find that the coherent portion inside the pulse-length of these two interactions due to the same phase has a very high Brillouin amplification. The Brillouin profile originating from the coherent interaction of pulse-pump with cw-pump results in high temperature and strain accuracy with centimeter resolution, which has been verified by successfully detecting 1.5 cm out-layer crack on an optical ground wire (OPGW) cable.

  13. ESTIMATION OF SOUNDING ABILITY OF A BRILLOUIN LIDAR IN THE EAST CHINA SEA

    Institute of Scientific and Technical Information of China (English)

    吴东; 宋小全; 刘智深

    2001-01-01

    Vertical profiles of sound speed in the sea can be measured by using laser excited Brillouin scattering. In this paper the dependence of the accuracy of sound speed measurement on the accuracy of the Brillouin shift measurement is analyzed. We calculated the maximum detecting depths of sound speed to an accuracy of 1 m/s by lidar with different laser pulse energy, platform altitude, telescope aperture and lidar effective attenuation coefficient. The estimation of sounding ability in the East China Sea is made in some stations. These data can be used in the design of Brillouin Lidar for the China Sea.

  14. Pressure and temperature dependences of the acoustic behaviors of biocompatible silk studied by using Brillouin spectroscopy

    Science.gov (United States)

    Lee, Byoung Wan; Ryeom, Junho; Ko, Jae-Hyeon; Kim, Dong Wook; Park, Chan Hum; Park, Jaehoon; Ko, Young Ho; Kim, Kwang Joo

    2016-07-01

    The elastic properties of a biocompatible silk film were investigated under temperature and pressure variations by using Brillouin spectroscopy. The Brillouin frequency shift decreased monotonically upon heating and showed a sudden change at the glass transition temperature. The existence of water molecules in the film increased the longitudinal modulus by approximately 10% and induced a relaxation peak in the hypersonic damping at ~60 ◦ C. The pressure dependences of the sound velocities of the longitudinal and the transverse acoustic modes and the refractive index were determined for the first time at pressures up to ~15.5 GPa. All these properties increased upon compression; these changes indicated that the free volume in the silk film collapsed at a pressure of about 3 GPa.

  15. Breakdown of the Brillouin limit and classical fluxes in rotating collisional plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rax, J. M., E-mail: jean-marcel.rax@polytechnique.edu [Université de Paris XI and LOA, ENSTA–Ecole Polytechnique, 91128 Palaiseau (France); Fruchtman, A. [HIT, Holon Institute of Technology, 52 Golomb St., Holon 58102 (Israel); Gueroult, R.; Fisch, N. J. [PPPL, Princeton University, Princeton, New Jersey 08540 (United States)

    2015-09-15

    The classical collisionless analysis displaying the occurrence of slow and fast rigid body rotation modes in magnetized plasmas is extended to collisional discharges. Collisions speed up the fast mode, slow down the slow one, and break down the classical Brillouin limit. Rigid body rotation has a strong impact on transport, and a collisional radial transport regime, different from the classical Braginskii collisional flux, is identified and analyzed.

  16. Modeling the effects of laser-beam smoothing on filamentation and stimulated Brillouin backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Berger, R.L.; Kaiser, T.B.; Lasinski, B.F. [and others

    1996-06-01

    Using the three-dimensional code (F3D), the authors compute the filamentation and backscattering of laser light. The results show that filamentation can be controlled and stimulated Brillouin backscattering (SBBS) can be reduced by using random phase plates (RPP) and small f-numbers or smoothing by spectral dispersion (SSD) with large bandwidth. An interesting result is that, for uniform plasmas, the SBBS amplification takes place over several laser axial coherence lengths (coherence length = speckle length).

  17. Physical and mathematical justification of the numerical Brillouin zone integration of the Boltzmann rate equation by Gaussian smearing

    Science.gov (United States)

    Illg, Christian; Haag, Michael; Teeny, Nicolas; Wirth, Jens; Fähnle, Manfred

    2016-03-01

    Scatterings of electrons at quasiparticles or photons are very important for many topics in solid-state physics, e.g., spintronics, magnonics or photonics, and therefore a correct numerical treatment of these scatterings is very important. For a quantum-mechanical description of these scatterings, Fermi's golden rule is used to calculate the transition rate from an initial state to a final state in a first-order time-dependent perturbation theory. One can calculate the total transition rate from all initial states to all final states with Boltzmann rate equations involving Brillouin zone integrations. The numerical treatment of these integrations on a finite grid is often done via a replacement of the Dirac delta distribution by a Gaussian. The Dirac delta distribution appears in Fermi's golden rule where it describes the energy conservation among the interacting particles. Since the Dirac delta distribution is a not a function it is not clear from a mathematical point of view that this procedure is justified. We show with physical and mathematical arguments that this numerical procedure is in general correct, and we comment on critical points.

  18. Absorption,fluorescence and resonance Rayleigh scattering spectra of hydrophobic hydrogen bonding of eosin Y/Triton X-100 nanoparticles and their analytical applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In a weak acidic medium(pH 2.4-2.8),eosin Y molecules(H2L) could replace water molecules to associate with Triton X-100 to form hydrophobic hydrogen bonding complexes.These complexes could further aggregate to form nanoparticles through the squeezing action of the water phase and Van Der Waals force,resulting in changes in the absorption spectrum and fluorescence quenching of EY as well as the significant enhancement of resonance Rayleigh scattering.This enables the sensitive determination of Triton X-100 using the fading spectrophotometry,fluorescence quenching method and RRS method.Among them,the RRS method shows the highest sensitivity with a detection limit of 20.6 ng mL-1 for Triton X-100.The optimum experimental conditions and factors that affect the absorption,fluorescence and RRS spectra were tested.The effects of coexisting substances were investigated and the results showed good selectivity.Based on these results,new spectrophotometric methods,fluorescence quenching method and RRS method for the determination of Triton X-100,were established.The hydrogen bonding association of eosin Y with Triton X-100 and the formation of nanoparticles as well as their effects on related spectral characteristics were discussed utilizing infrared,transmission electron microscope technique and quantum chemical method.

  19. Incoherent scatter spectra due to HF heating in the low ionosphere region

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere region are presented with consideration of the elastic collision between electrons and neural particles and the excitation of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian feature is weak- ened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be con- sidered in the inversion.

  20. Incoherent scatter spectra due to HF heating in the low ionosphere region

    Institute of Scientific and Technical Information of China (English)

    XU Bin; WU ZhenSen; WU Jian; XUE Kun

    2009-01-01

    The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere region are presented with consideration of the elastic collision between electrons and neural particles and the excitation of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered in the inversion.

  1. Strong scintillations during atmospheric occultations Theoretical intensity spectra. [radio scattering during spacecraft occultations by planetary atmospheres

    Science.gov (United States)

    Hinson, D. P.

    1986-01-01

    Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

  2. Resolving the bulk ion region of millimeter-wave collective Thomson scattering spectra at ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Stejner, M., E-mail: mspe@fysik.dtu.dk; Nielsen, S.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Meo, F.; Michelsen, P. K.; Rasmussen, J.; Salewski, M. [Department of Physics, Association EURATOM-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Moseev, D. [Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Boltzmannstr. 2, 85748 Garching (Germany); Association Euratom-FOM Institute DIFFER, 3430 BE Nieuwegein (Netherlands); Schubert, M.; Stober, J.; Wagner, D. H. [Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Boltzmannstr. 2, 85748 Garching (Germany)

    2014-09-15

    Collective Thomson scattering (CTS) measurements provide information about the composition and velocity distribution of confined ion populations in fusion plasmas. The bulk ion part of the CTS spectrum is dominated by scattering off fluctuations driven by the motion of thermalized ion populations. It thus contains information about the ion temperature, rotation velocity, and plasma composition. To resolve the bulk ion region and access this information, we installed a fast acquisition system capable of sampling rates up to 12.5 GS/s in the CTS system at ASDEX Upgrade. CTS spectra with frequency resolution in the range of 1 MHz are then obtained through direct digitization and Fourier analysis of the CTS signal. We here describe the design, calibration, and operation of the fast receiver system and give examples of measured bulk ion CTS spectra showing the effects of changing ion temperature, rotation velocity, and plasma composition.

  3. Interatomic scattering in energy dependent photoelectron spectra of Ar clusters

    Energy Technology Data Exchange (ETDEWEB)

    Patanen, M.; Benkoula, S.; Nicolas, C.; Goel, A. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Antonsson, E. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Physikalische und Theoretische Chemie Institut für Chemie und Biochemie, Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin (Germany); Neville, J. J. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 6E2 (Canada); Miron, C., E-mail: Catalin.Miron@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Extreme Light Infrastructure - Nuclear Physics (ELI-NP), ‘Horia Hulubei’ National Institute for Physics and Nuclear Engineering, 30 Reactorului Street, RO-077125 Măgurele, Jud. Ilfov (Romania)

    2015-09-28

    Soft X-ray photoelectron spectra of Ar 2p levels of atomic argon and argon clusters are recorded over an extended range of photon energies. The Ar 2p intensity ratios between atomic argon and clusters’ surface and bulk components reveal oscillations similar to photoelectron extended X-ray absorption fine structure signal (PEXAFS). We demonstrate here that this technique allows us to analyze separately the PEXAFS signals from surface and bulk sites of free-standing, neutral clusters, revealing a bond contraction at the surface.

  4. Energy spectra of low-energy ions scattered by polycrystal surfaces

    International Nuclear Information System (INIS)

    Full text: The interaction of low-energy ions with solid surfaces has recently drawn considerable interest. This interest is defined by both the development of methods of diagnostics with use of ion beams, technology of ion-plasma deposition, ion beam epitaxy, ion implantation, and by necessity of full understanding of the mechanisms of the phenomena that follow the interaction of atomic particles with the solid surface. In the present work an experimental study of low-energy (E0 = 30-500 eV) Cs+ ions scattering on the Ta, W, Re target surfaces and K+ ions scattering on Ti, V, Cr target surfaces have been performed for more accurate definition of mechanism of scattering with a purpose of evaluation of an opportunity of use of slow ions scattering as a tool of surface layers analysis. The choice of the targets was caused by the fact that the ratios of atomic masses of target atoms and ions μ=m2/m1 were almost the same for all cases considered and greater than 1 (direct mass ratio) and the difference of binding energies of target atoms in both cases of Cs+ and K+ ions scattering was almost as twice. The angles of incidence ψ=55 deg. and scattering θ=70 deg. correspond to the specular reflection condition. It has been shown that the energy spectra of scattered ions have a characteristic shape with a maximum at the low energy. At initial energy decreasing positions of maxima in spectra for all targets displace to the high energy region relatively to calculated one for binary elastic scattering. Note that the smallest displacement of maxima was observed for scattering of Cs+ on W and K+ on V - targets (μ>1), which possess the highest binding energy. At the same time in the earlier investigated by us inverse mass ratio case (Cs+ on Al, Si, Ni targets: μ+ on Al). This fact point to the differences in mechanisms of many particle interaction of low-energy ions with atoms of polycrystal surfaces at direct and inverse mass ratio of colliding particles and justifies the

  5. Incoherent scatter spectra from plasma of a 13-moment approximation distribution function

    Institute of Scientific and Technical Information of China (English)

    XU Bin; XUE Kun; WU Jian; WU ZhenSen

    2008-01-01

    The function and physical mechanism of heat flow and the viscous stress in the velocity distribution function expanded by Maxwellian distribution are presented.With the introduction of effective temperature Tf,incoherent scatter spectra from plasma for electromagnetic wave in arbitrary line of sight are given.The effect of asymmetry and anisotropy provided by heat flow and the viscous stress on power spectra is discussed.Radar spectra are calculated for different cases of electric field,direction,collision frequency and temperature.The effect of heat flow and the viscous stress on inversion results is analyzed.With a large electric field,the character of non-Maxwellian must be considered.

  6. Differing self-similarity in light scattering spectra: A potential tool for pre-cancer detection

    CERN Document Server

    Ghosh, Sayantan; Purwar, Harsh; Jagtap, Jaidip; Pradhan, Asima; Ghosh, Nirmalya; Panigrahi, Prasanta K

    2011-01-01

    The fluctuations in the elastic light scattering spectra of normal and dysplastic human cervical tissues analyzed through wavelet transform based techniques reveal clear signatures of self-similar behavior in the spectral fluctuations. Significant differences in the power law behavior ascertained through the scaling exponent was observed in these tissues. The strong dependence of the elastic light scattering on the size distribution of the scatterers manifests in the angular variation of the scaling exponent. Interestingly, the spectral fluctuations in both these tissues showed multi-fractality (non-stationarity in fluctuations), the degree of multi-fractality being marginally higher in the case of dysplastic tissues. These findings using the multi-resolution analysis capability of the discrete wavelet transform can contribute to the recent surge in the exploration for non-invasive optical tools for pre-cancer detection.

  7. Experimental observation of fundamental and harmonic self pulse generation of single high-order Stokes in Brillouin Erbium fiber laser

    Science.gov (United States)

    Wang, Xiaorui; Yang, Yanfu; Liu, Meng; Yao, Yong

    2016-07-01

    Fundamental and harmonic self-pulse generation was experimentally observed on both first order and higher order Stokes components. The generated pulses with the same order harmonic repetition rate are obtained on multiple Stokes components simultaneously. The pulse generation on first order Stokes component can be attributed to periodic pump depletion in Brillouin gain medium. The pulse generation of high order Stokes component can be considered as pulse oscillation pumped by the former order Stokes. With high Erbium pump power, by setting the proper attenuation between Brillouin medium and Faraday rotation mirror, the harmonic pulse generations up to fifth order have been achieved.

  8. Analysis of beam plasma instability effects on incoherent scatter spectra

    Directory of Open Access Journals (Sweden)

    M. A. Diaz

    2010-12-01

    Full Text Available Naturally Enhanced Ion Acoustic Lines (NEIALs detected with Incoherent Scatter Radars (ISRs can be produced by a Langmuir decay mechanism, triggered by a bump on tail instability. A recent model of the beam-plasma instability suggests that weak-warm beams, such those associated with NEIAL events, might produce Langmuir harmonics which could be detected by a properly configured ISR. The analysis performed in this work shows that such a beam-driven wave may be simultaneously detected with NEIALs within the baseband signal of a single ISR. The analysis shows that simultaneous detection of NEIALs and the first Langmuir harmonic is more likely than simultaneous detection of NEIALs and enhanced plasma line. This detection not only would help to discriminate between current NEIAL models, but could also aid in the parameter estimation of soft precipitating electrons.

  9. Phonon dynamics and inelastic neutron scattering of sodium niobate

    Science.gov (United States)

    Mishra, S. K.; Gupta, M. K.; Mittal, R.; Zbiri, M.; Rols, S.; Schober, H.; Chaplot, S. L.

    2014-05-01

    Sodium niobate (NaNbO3) exhibits an extremely complex sequence of structural phase transitions in the perovskite family and therefore provides an excellent model system for understanding the mechanism of structural phase transitions. We report temperature dependence of inelastic neutron scattering measurements of phonon densities of states in sodium niobate. The measurements are carried out in various crystallographic phases of this material at various temperatures from 300 to 1048 K. The phonon spectra exhibit peaks centered on 19, 37, 51, 70, and 105 meV. Interestingly, the peak near 70 meV shifts significantly towards lower energy with increasing temperature, while the other peaks do not exhibit any appreciable shift. The phonon spectra at 783 K show prominent change and become more diffusive as compared to those at 303 K. In order to better analyze these features, we have performed first-principles lattice dynamics calculations based on the density functional theory. The computed phonon density of states is found to be in good agreement with the experimental data. Based on our calculation we are able to assign the characteristic Raman modes in the antiferroelectric phase, which are due to the folding of the T (ω = 95 cm-1) and Δ (ω = 129 cm-1) points of the cubic Brillouin zone, to the A1g symmetry.

  10. Gamma radiation influence on silica optical fibers measured by optical backscatter reflectometry and Brillouin sensing technique

    Science.gov (United States)

    Wosniok, A.; Sporea, D.; Neguţ, D.; Krebber, K.

    2016-05-01

    We have studied the influence of gamma rays on physical properties of different commercially available silica optical fibers stepwise irradiated up to a total dose of 100 kGy. The detection of radiation-induced changes in silica glass offers the possibility of using selected optical fibers as distributed radiation sensors. The measurements performed by us were based on optical backscatter reflectometry and Brillouin distributed sensing. The measurement methods enable an analysis of radiation-induced modification of the group refractive index and density of the optical fibers. The most distinct physical effect observed by us concerns the increase of the optical attenuation with rising total radiation doses. Quantitative measurement results indicate a crucial impact of fiber dopants on radiation-induced physical and sensory characteristics of silica optical fibers affected by differences in fiber fabrication techniques. Based on the obtained results, the suitability of distributed Brillouin sensing for dosimetry applications seems to be improved by modifying the refractive index profile of the fiber core.

  11. Biophotonics of skin: method for correction of deep Raman spectra distorted by elastic scattering

    Science.gov (United States)

    Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Gobinet, Cyril; Manfait, Michel; Dinten, Jean-Marc

    2015-03-01

    Confocal Raman microspectroscopy allows in-depth molecular and conformational characterization of biological tissues non-invasively. Unfortunately, spectral distortions occur due to elastic scattering. Our objective is to correct the attenuation of in-depth Raman peaks intensity by considering this phenomenon, enabling thus quantitative diagnosis. In this purpose, we developed PDMS phantoms mimicking skin optical properties used as tools for instrument calibration and data processing method validation. An optical system based on a fibers bundle has been previously developed for in vivo skin characterization with Diffuse Reflectance Spectroscopy (DRS). Used on our phantoms, this technique allows checking their optical properties: the targeted ones were retrieved. Raman microspectroscopy was performed using a commercial confocal microscope. Depth profiles were constructed from integrated intensity of some specific PDMS Raman vibrations. Acquired on monolayer phantoms, they display a decline which is increasing with the scattering coefficient. Furthermore, when acquiring Raman spectra on multilayered phantoms, the signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties of any biological sample, obtained with DRS for example, is crucial to correct properly Raman depth profiles. A model, inspired from S.L. Jacques's expression for Confocal Reflectance Microscopy and modified at some points, is proposed and tested to fit the depth profiles obtained on the phantoms as function of the reduced scattering coefficient. Consequently, once the optical properties of a biological sample are known, the intensity of deep Raman spectra distorted by elastic scattering can be corrected with our reliable model, permitting thus to consider quantitative studies for purposes of characterization or diagnosis.

  12. Quasi distributed hybrid Brillouin fiber laser sensor system

    International Nuclear Information System (INIS)

    A hybrid quasi distributed sensing system combining point fiber Bragg gratings and long integral Brillouin scattering transducers is presented. It is able to measure global temperature changes along the sensing line as well as punctual changes at the critical locations of the structure. A 20 km proof-of-concept system has been experimentally demonstrated with a temperature resolution of 0.47 °C. (paper)

  13. Self-pulsation threshold of Raman amplified Brillouin fiber cavities

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Pedersen, Martin Erland Vestergaard; Rottwitt, Karsten

    2009-01-01

    An implicit equation for the oscillation threshold of stimulated Brillouin scattering from Raman amplified signals in fibers with external feedback is derived under the assumption of no depletion. This is compared to numerical investigations of Raman amplification schemes showing good agreement...... for high reflectivities. For low reflectivities and high attenuation or long fibers, the assumption of no depletion is shown not to be valid. In these cases the effects of the depletion on the self-pulsation is examined....

  14. Suppression of stimulated Brillouin instability of a beat-wave of two lasers in multiple-ion-species plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Pinki; Gupta, D. N., E-mail: dngupta@physics.du.ac.in; Avinash, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India)

    2016-01-15

    Stimulated Brillouin instability of a beat-wave of two lasers in plasmas with multiple-ion-species (negative-ions) was studied. The inclusion of negative-ions affects the growth of ion-acoustic wave in Brillouin scattering. Thus, the growth rate of instability is suppressed significantly by the density of negative-ions. To obey the phase-matching condition, the growth rate of the instability attains a maxima for an appropriate scattering angle (angle between the pump and scattered sideband waves). This study would be technologically important to have diagnostics in low-temperature plasmas.

  15. Acoustic and relaxation behaviors of polydimethylsiloxane studied by using brillouin and dielectric spectroscopies

    Science.gov (United States)

    Lee, Byoung Wan; Ko, Jae-Hyeon; Park, Jaehoon; Shin, Dong-Myeong; Hwang, Yoon-Hwae

    2016-04-01

    The temperature dependences of the acoustic properties and the dielectric relaxation times of polydimethylsiloxane were investigated by using high-resolution Brillouin and broadband dielectric spectroscopies. The longitudinal sound velocity showed a large increase upon approaching the glass transition temperature while the acoustic absorption coefficient exhibited a maximum at ~263 K. Comparison of these results with previous ultrasonic data revealed a substantial frequency dispersion of the acoustic properties of this silicone-based elastomer. The relaxation times derived from the acoustic absorption peaks were consistent with the temperature dependence of the dielectric relaxation time of the structural a process, indicating a strong coupling between the acoustic waves and the segmental motions of the main chains.

  16. Studying the fine structure of coherent echo spectra using data from Irkutsk incoherent scatter radar

    Science.gov (United States)

    Berngardt, O. I.; Potekhin, A. P.

    2009-12-01

    Studying the processes generating different-scale inhomogeneities is one of the challenging problems of ionospheric physics. Plasma instabilities are one of the physical mechanisms by which small-scale inhomogeneities are formed. The main forms of instability in the ionospheric E-layer are two-stream and gradient-drift ones. The inhomogeneities generated by them lead to an abnormally intense radio scattering of different wavelengths (known as coherent echo (CE) or radio aurora) in the E-layer. Therefore, the method of radiowave backscattering is among the widely used methods for studying such inhomogeneities. The CE phenomenon has been investigated most intensely at high and equatorial latitudes, where the conditions for the CE origination are formed rather regularly. For the last decade, CE has also been intensely studied at midlatitudes, where it is observed less frequently and its formation conditions are less known. In 1998-2006, the purposeful studies of the midlatitude CE peculiarities were performed at the Irkutsk incoherent scatter (IS) radar, with a particular emphasis on its coherent properties. It was for the first time found out that the spectra of some data sets had a fine comb-shaped structure, which generated well-known single-humped CE spectra as a result of statistical averaging. In the scope of this study, unique coherent methods for processing individual data sets of CE signals were developed, making it possible to reveal the peculiarities of unaveraged CE-signal spectra. To describe these peculiarities, we proposed a new model of the inhomogeneity spectrum, which is the superposition of the discrete set of spatial harmonics with close wave numbers. The model was shown to adequately describe the scattered signal characteristics observed experimentally.

  17. Influence of the Pseudogap on the Inelastic Neutron Scattering Spectra of the Underdoped Lanthanum Cuprate

    Institute of Scientific and Technical Information of China (English)

    LOU Ping; CAO Lie-Zhao; WU Hang-Sheng

    2002-01-01

    The influence of pseudogap on the inelastic neutron scattering spectra of the underdoped lanthanum cuprate is studied on the basis of the model which incorporates both the superconducting state and pscudogap state.It is found that the striking effects of the influence of the pseudogap on the incommensurability of the spin excitation spectrum are that in the superconducting state the pseudogap makes the intensity of the incommensurate peak increase,in the normal state the pseudogap not only makes the intensity of the incommensurate peak increase,but also sharpens the incommensurate peak and increases incommensurability.

  18. Tunable and reconfigurable multi-tap microwave photonic filter based on dynamic Brillouin gratings in fibers.

    Science.gov (United States)

    Sancho, J; Primerov, N; Chin, S; Antman, Y; Zadok, A; Sales, S; Thévenaz, L

    2012-03-12

    We propose and experimentally demonstrate new architectures to realize multi-tap microwave photonic filters, based on the generation of a single or multiple dynamic Brillouin gratings in polarization maintaining fibers. The spectral range and selectivity of the proposed periodic filters is extensively tunable, simply by reconfiguring the positions and the number of dynamic gratings along the fiber respectively. In this paper, we present a complete analysis of three different configurations comprising a microwave photonic filter implementation: a simple notch-type Mach-Zehnder approach with a single movable dynamic grating, a multi-tap performance based on multiple dynamic gratings and finally a stationary grating configuration based on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS). PMID:22418495

  19. Interpretation of HF radar ionospheric Doppler spectra by collective wave scattering theory

    Science.gov (United States)

    Hanuise, C.; Villain, J. P.; Gresillon, D.; Cabrit, B.; Greenwald, R. A.; Baker, K. B.

    1993-01-01

    The correlation length and time constant of turbulent plasma motion is determined using the coherent radar autocorrelation function (ACF) in the framework of collective wave scattering theory by a nonuniform plasma. It is concluded that the observed Doppler spectra have either a Lorentzian shape or a Gaussian shape according to the size of the correlation length of the plasma motion as compared to the observed fluctuation wavelength. Observations indicate that the Lorentzian shape is most common. When the correlation length of the plasma motion is much greater than the observed fluctuation wavelength, the Doppler spectrum becomes Gaussian shaped.

  20. Comparison of Surface-enhanced Raman Scattering Spectra of Two Kinds of Silver Nanoplate Films

    Institute of Scientific and Technical Information of China (English)

    TAO Jin-long; TANG Bin; XU Shu-ping; PAN Ling-yun; XU Wei-qing

    2012-01-01

    Surface-enhanced Raman scattering(SERS) spectra of different silver nanoplate self-assembled films at different excitation wavelengths were fairly compared.Shape conversion from silver nanoprisms to nanodisks on slides was in situ carried out.The SERS spectra of 4-mercaptopyridine(4-MPY) on these anisotropic silver nanoparticle self-assembled films present that strong enhancement appeared when the excitation line and the surface plasmon resonance(SPR) band of silver substrate overlapped.In this model,the influence of the crystal planes of silver nanoplates on SERS enhancement could be ignored because the basal planes were nearly unchanged in two kinds of silver nanoplate self-assembled films.

  1. Spectra and strains

    CERN Document Server

    Golyshev, V

    2008-01-01

    This is a blend of two informal reports on the activities of the seminar on Galois representations and mirror symmetry given at the Conference on classification problems and mirror duality at the Steklov Institute, in March 2006, and at the Seminar on Algebra, Geometry and Physics at MPI, in November 2007. We assess where we are on the issue of the spectra of Fano varieties, and state problems. We introduce higher dimensional irreducible analogues of dessins, the low ramified sheaves, and hypothesize that Fano spectra relate to their geometric conductors. We give a recipe to a physicist.

  2. All solid-state diode pumped Nd:YAG MOPA with stimulated Brillouin phase conjugate mirror

    NARCIS (Netherlands)

    Offerhaus, H.L.; Godfried, H.P.; Witteman, W.J.

    1996-01-01

    At the Nederlands Centrum voor Laser Research (NCLR) a 1 kHz diode-pumped Nd:YAG Master Oscillator Power Amplifier (MOPA) chain with a Stimulated Brillouin Scattering (SBS) Phase Conjugate mirror is designed and operated. A small Brewster angle Nd:YAG slab (2 by 2 by 20 mm) is side pumped with 200 μ

  3. KrF laser amplifier with phase-conjugate Brillouin retroreflectors.

    Science.gov (United States)

    Gower, M C

    1982-09-01

    We have demonstrated the use of phase-conjugate stimulated Brillouin scattering mirrors to produce high-quality, short-pulse KrF laser beams from angular multiplexed and regenerative amplifiers. The mirror was also shown to isolate systems optically from amplifier spontaneous emission. Automatic alignment of targets using this mirror as a retroreflector was also demonstrated.

  4. KrF laser amplifier with phase-conjugate Brillouin retroreflectors.

    Science.gov (United States)

    Gower, M C

    1982-09-01

    We have demonstrated the use of phase-conjugate stimulated Brillouin scattering mirrors to produce high-quality, short-pulse KrF laser beams from angular multiplexed and regenerative amplifiers. The mirror was also shown to isolate systems optically from amplifier spontaneous emission. Automatic alignment of targets using this mirror as a retroreflector was also demonstrated. PMID:19714043

  5. Measurement of multiplicity and momentum spectra in the current and target regions of the Breit frame in Deep Inelastic Scattering at HERA

    CERN Document Server

    Abbiendi, G; Abramowicz, H; Acosta, D; Adamczyk, L; Adamus, M; Ahn, S H; Amelung, C; An Shiz Hong; Anselmo, F; Antonioli, P; Arneodo, M; Bacon, Trevor C; Badgett, W F; Bailey, D C; Bailey, D S; Bamberger, A; Barbagli, G; Bari, G; Barreiro, F; Barret, O; Bashindzhagian, G L; Bashkirov, V; Basile, M; Bauerdick, L A T; Bednarek, B; Behrens, U; Beier, H; Bellagamba, L; Bertolin, A; Bhadra, S; Bienlein, J K; Blaikley, H E; Bohnet, I; Bokel, C; Bornheim, A; Borzemski, P; Boscherini, D; Botje, M; Breitweg, J; Brock, I; Bromley, J T; Brook, N H; Brugnera, R; Brümmer, N; Bruni, A; Bruni, G; Burgard, C; Burow, B D; Bussey, P J; Butterworth, J M; Bylsma, B; Caldwell, A; Capua, M; Cara Romeo, G; Carlin, R; Cartiglia, N; Cashmore, R J; Castellini, G; Catterall, C D; Chapin, D; Chekanov, S; Chwastowski, J; Ciborowski, J; Cifarelli, Luisa; Cindolo, F; Cirio, R; Cloth, P; Coboken, K; Coldewey, C; Cole, J E; Contin, A; Cooper-Sarkar, A M; Coppola, N; Cormack, C; Corradi, M; Corriveau, F; Costa, M; Cottingham, W N; Crittenden, J; Cross, R; D'Agostini, G; Dagan, S; Dal Corso, F; Dardo, M; De Pasquale, S; Deffner, R; Deppe, O; Derrick, M; Deshpande, Abhay A; Desler, K; Devenish, R C E; Dhawan, S; Dolgoshein, B A; Dosselli, U; Doyle, A T; Drews, G; Dulinski, Z; Durkin, L S; Dusini, S; Eckert, M; Edmonds, J K; Eisenberg, Y; Eisenhardt, S; Engelen, J; Epperson, D E; Ermolov, P F; Eskreys, Andrzej; Fagerstroem, C P; Fernández, J P; Ferrero, M I; Figiel, J; Filges, D; Foster, B; Foudas, C; Fox-Murphy, A; Fricke, U; Frisken, W R; Fusayasu, T; Gadaj, T; Galea, R; Gallo, E; García, G; Garfagnini, A; Gendner, N; Gialas, I; Gilmore, J; Ginsburg, C M; Giusti, P; Gladilin, L K; Glasman, C; Göbel, F; Golubkov, Yu A; Göttlicher, P; Grabosch, H J; Graciani, R; Grosse-Knetter, J; Grzelak, G; Haas, T; Hain, W; Hall-Wilton, R; Hamatsu, R; Hanna, D S; Harnew, N; Hart, J C; Hartmann, H; Hartmann, J; Hartner, G F; Hasell, D; Hayes, M E; Heaphy, E A; Heath, G P; Heath, H F; Hebbel, K; Heinloth, K; Heinz, L; Hernández, J M; Heusch, C A; Hilger, E; Hirose, T; Hochman, D; Holm, U; Homma, K; Hong, S J; Howell, G; Hughes, V W; Iacobucci, G; Iannotti, L; Iga, Y; Inuzuka, M; Ishii, T; Jakob, H P; Jelen, K; Jeoung, H Y; Jing, Z; Johnson, K F; Jones, T W; Kananov, S; Kappes, A; Karshon, U; Kasemann, M; Katz, U F; Kcira, D; Kerger, R; Khakzad, M; Khein, L A; Kim, C L; Kim, J Y; Kisielewska, D; Kitamura, S; Klanner, Robert; Klimek, K; Koch, W; Koffeman, E; Kooijman, P; Koop, T; Korotkova, N A; Korzhavina, I A; Kotanski, A; Kötz, U; Kowal, A M; Kowalski, H; Kowalski, T; Krakauer, D; Kreisel, A; Kuze, M; Kuzmin, V A; Labarga, L; Lamberti, L; Lane, J B; Laurenti, G; Lee, J H; Lee, S B; Lee, S W; Levi, G; Levman, G M; Levy, A; Lim, H; Lim, I T; Limentani, S; Lindemann, L; Ling, T Y; Liu, W; Löhr, B; Lohrmann, E; Long, K R; Lopez-Duran Viani, A; Lukina, O Yu; Ma, K J; Maccarrone, G; MacDonald, N; Magill, S; Mallik, U; Margotti, A; Marini, G; Markun, P; Martin, J F; Martínez, M; Maselli, S; Massam, Thomas; Mastroberardino, A; Matsushita, T; Mattingly, M C K; Mattingly, S E K; McCance, G J; McCubbin, N A; McFall, J D; Mellado, B; Menary, S; Meyer, A; Meyer-Larsen, A; Milewski, J; Milite, M; Miller, D B; Monaco, V; Mönig, K; Monteiro, T; Morandin, M; Moritz, M; Murray, W N; Musgrave, B; Nagano, K; Nam, S W; Nania, R; Nigro, A; Nishimura, T; Notz, D; Nowak, R J; Noyes, V A; Nylander, P; Ochs, A; Oh, B Y; Okrasinski, J R; Olkiewicz, K; Orr, R S; Pac, M Y; Padhi, S; Palmonari, F; Park, I H; Park, S K; Parsons, J A; Paul, E; Pavel, N; Pawlak, J M; Pawlak, R; Pelfer, Pier Giovanni; Pellegrino, A; Pelucchi, F; Peroni, C; Pesci, A; Petrucci, M C; Pfeiffer, M; Piccioni, D; Piotrzkowski, K; Poelz, G; Polenz, S; Polini, A; Posocco, M; Prinias, A; Proskuryakov, A S; Przybycien, M B; Puga, J; Quadt, A; Raach, H; Raso, M; Rautenberg, J; Redondo, I; Reeder, D D; Repond, J; Ritz, S; Riveline, M; Rohde, M; Rulikowska-Zarebska, E; Ruske, O; Ruspa, M; Sabetfakhri, A; Sacchi, R; Sadrozinski, H F W; Salehi, H; Sampson, S; Sartorelli, G; Saull, P R B; Savin, A A; Saxon, D H; Schechter, A; Schioppa, M; Schlenstedt, S; Schmidke, W B; Schneekloth, U; Schnurbusch, H; Schwarzer, O; Sciulli, F; Scott, J; Sedgbeer, J K; Seiden, A; Selonke, F; Shah, T P; Shcheglova, L M; Sideris, D; Sievers, M; Simmons, D; Sinclair, L E; Skillicorn, I O; Smalska, B; Smith, W H; Solano, A; Solomin, A N; Son, D; Saint-Laurent, M G; Staiano, A; Stairs, D G; Stanco, L; Stanek, R; Stifutkin, A; Stonjek, S; Straub, P B; Strickland, E; Stroili, R; Susinno, G; Suszycki, L; Sutton, M R; Suzuki, I; Tandler, J; Tapper, A D; Tapper, R J; Tassi, E; Terron, J; Tiecke, H G; Tokushuku, K; Toothacker, W S; Tsurugai, T; Tuning, N; Tymieniecka, T; Umemori, K; Vaiciulis, A W; Velthuis, J J; Verkerke, W; Voci, C; Vossebeld, Joost Herman; Votano, L; Walczak, R; Walker, R; Wang, S M; Waters, D S; Waugh, R; Weber, A; Westphal, D; Whitmore, J J; Wichmann, R; Wick, K; Wieber, H; Wiggers, L; Wildschek, T; Williams, D C; Wills, H H; Wing, M; Wodarczyk, M; Wolf, G; Wölfle, S; Wollmer, U; Wróblewski, A K; Yamada, S; Yamashita, T; Yamauchi, K; Yamazaki, Y; Yoshida, R; Youngman, C; Zajac, J; Zakrzewski, J A; Zamora Garcia, Y; Zawiejski, L; Zetsche, F; Zeuner, W; Zhu, Q; Zichichi, Antonino; Zotkin, S A; De Wolf, E; Del Peso, J; Van Sighem, A

    1999-01-01

    Charged particle production in neutral current deep inelastic scattering (DIS) has been studied using the ZEUS detector.The evolution of the mean multiplicities, scaled momenta and transverse momenta in Q^2 and x for $10 6\\times 10^{-4}$ has been investigated in the current and target fragmentation regions of the Breit frame. Distributions in the target region, using HERA data for the first time, are compared to distributions in the current region. Predictions based on MLLA and LPHD are inconsistent with the data.

  6. Linked Scatter Plots, A Powerful Exploration Tool For Very Large Sets of Spectra

    Science.gov (United States)

    Carbon, Duane Francis; Henze, Christopher

    2015-08-01

    We present a new tool, based on linked scatter plots, that is designed to efficiently explore very large spectrum data sets such as the SDSS, APOGEE, LAMOST, GAIA, and RAVE data sets.The tool works in two stages: the first uses batch processing and the second runs interactively. In the batch stage, spectra are processed through our data pipeline which computes the depths relative to the local continuum at preselected feature wavelengths. These depths, and any additional available variables such as local S/N level, magnitudes, colors, positions, and radial velocities, are the basic measured quantities used in the interactive stage.The interactive stage employs the NASA hyperwall, a configuration of 128 workstation displays (8x16 array) controlled by a parallelized software suite running on NASA's Pleiades supercomputer. Each hyperwall panel is used to display a fully linked 2-D scatter plot showing the depth of feature A vs the depth of feature B for all of the spectra. A and B change from panel to panel. The relationships between the various (A,B) strengths and any distinctive clustering, as well as unique outlier groupings, are visually apparent when examining and inter-comparing the different panels on the hyperwall. In addition, the data links between the scatter plots allow the user to apply a logical algebra to the measurements. By graphically selecting the objects in any interesting region of any 2-D plot on the hyperwall, the tool immediately and clearly shows how the selected objects are distributed in all the other 2-D plots. The selection process may be repeated multiple times and, at each step, the selections can represent a sequence of logical constraints on the measurements, revealing those objects which satisfy all the constraints thus far. The spectra of the selected objects may be examined at any time on a connected workstation display.Using over 945,000,000 depth measurements from 569,738 SDSS DR10 stellar spectra, we illustrate how to quickly

  7. Statistical analysis of polarization-inhomogeneous Fourier spectra of laser radiation scattered by human skin in the tasks of differentiation of benign and malignant formations

    Science.gov (United States)

    Ushenko, Alexander G.; Dubolazov, Alexander V.; Ushenko, Vladimir A.; Novakovskaya, Olga Y.

    2016-07-01

    The optical model of formation of polarization structure of laser radiation scattered by polycrystalline networks of human skin in Fourier plane was elaborated. The results of investigation of the values of statistical (statistical moments of the 1st to 4th order) parameters of polarization-inhomogeneous images of skin surface in Fourier plane were presented. The diagnostic criteria of pathological process in human skin and its severity degree differentiation were determined.

  8. Non-LTE Models and Theoretical Spectra of Accretion Disks in Active Galactic Nuclei. IV. Effects of Compton Scattering and Metal Opacities

    CERN Document Server

    Hubeny, I; Krolik, J H; Agol, E; Hubeny, Ivan; Blaes, Omer; Krolik, Julian H.

    2001-01-01

    We extend our models of the vertical structure and emergent radiation field of accretion disks around supermassive black holes described in previous papers of this series. Our models now include both a self-consistent treatment of Compton scattering and the effects of continuum opacities of the most important metal species (C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni). With these new effects incorporated, we compute the predicted spectrum from black holes accreting at nearly the Eddington luminosity (L/L_Edd = 0.3) and central masses of 10^6, 10^7, and 10^8 M_sun. We also consider two values of the Shakura-Sunyaev alpha parameter, 0.1 and 0.01. Although it has little effect when M > 10^8 M_sun, Comptonization grows in importance as the central mass decreases and the central temperature rises. It generally produces an increase in temperature with height in the uppermost layers of hot atmospheres. Compared to models with coherent electron scattering, Comptonized models have enhanced EUV/soft X-ray emission, but they...

  9. Coherent frequency-modulated continuous wave reflectometry for measuring stationary Brillouin grating induced under uniform pumping by counterpropagating nonmodulated light waves.

    Science.gov (United States)

    Takada, Kazumasa; Yasuno, Takahiro

    2016-05-20

    We describe theoretically and experimentally how valuable information on the distributed Brillouin spectra of an optical waveguide is derived from the stationary Brillouin grating measurement under uniform pumping over the waveguide by using the coherent frequency-modulated continuous wave reflectometry. We upconvert the frequencies of the probe and pumping light waves by the Brillouin frequency with one modulator and detect the Stokes light in the same way that we detect the Fresnel and Rayleigh backreflections in the fiber. The intrinsic coherent spike is reduced by using the lock-in detection and the least squares method to reveal the distributed Brillouin spectra of a short optical fiber consisting of two different fibers spliced together. PMID:27411124

  10. A high-efficiency Brillouin fiber ring laser

    Institute of Scientific and Technical Information of China (English)

    Pingping Zhang; Shuling Hu; Shuying Chen; Yuanhong Yang; Chunxi Zhang

    2009-01-01

    A high-efficiency Brillouin fiber ring laser is demonstrated using the standard single-mode fiber.The laser exhibits a 3.6-mW threshold.The output power is 22 mW with 40-nlW pump power,and the maximum optical-to-optical efficiency is 55%. The output is single wavelength with a 3-dB linewidth of 5 MHz,and the interval of center frequency between the laser and the pump light is 11 GHz (0.088 nm).It is shown that the stimulated Brillouin scattering threshold of ring resonator is lower and the energy transfer efficiency is higher than those in fiber.

  11. The effect of Compton scattering on gamma-ray spectra of the 2005 January 20 flare

    Institute of Scientific and Technical Information of China (English)

    Wei Chen; Wei-Qun Gan

    2012-01-01

    Gamma-ray spectroscopy provides a wealth of information about accelerated particles in solar flares,as well as the ambient medium with which these energetic particles interact.The neutron capture line (2.223 MeV),the strongest in the solar gamma-ray spectrum,forms in the deep atmosphere.The energy of these photons can be reduced via Compton scattering.With the fully relativistic GEANT4 toolkit,we have carried out Monte Carlo simulations of the transport of a neutron capture line in solar flares,and applied them to the flare that occurred on 2005 January 20 (X7.1/2B),one of the most powerful gamma-ray flares observed by RHESSI during the 23rd solar cycle.By comparing the fitting results of different models with and without Compton scattering of the neutron capture line,we find that when including the Compton scattering for the neutron capture line,the observed gamma-ray spectrum can be reproduced by a population of accelerated particles with a very hard spectrum (s≤2.3).The Compton effect of a 2.223 MeV line on the spectra is therefore proven to be significant,which influences the time evolution of the neutron capture line flux as well.The study also suggests that the mean vertical depth for neutron capture in hydrogen for this event is about 8 g cm-2.

  12. Measurement of Feynman-x Spectra of Photons and Neutrons in the Very Forward Direction in Deep-Inelastic Scattering at HERA

    CERN Document Server

    Andreev, V.; Begzsuren, K.; Belousov, A.; Belov, P.; Boudry, V.; Brandt, G.; Brinkmann, M.; Brisson, V.; Britzger, D.; Buniatyan, A.; Bylinkin, A.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Ceccopieri, F.; Cerny, K.; Chekelian, V.; Contreras, J.G.; Dainton, J.B.; Daum, K.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dossanov, A.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Ferencei, J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grindhammer, G.; Haidt, D.; Henderson, R.C.W.; Herbst, M.; Hladky, J.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Jacquet, M.; Janssen, X.; Jung, H.; Kapichine, M.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kogler, R.; Kostka, P.; Kretzschmar, J.; Kruger, K.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Lytkin, L.; Malinovski, E.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Morozov, A.; Muller, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nowak, G.; Nowak, K.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Pascaud, C.; Patel, G.D.; Perez, E.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shushkevich, S.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Steder, M.; Stella, B.; Straumann, U.; Sykora, T.; Thompson, P.D.; Traynor, D.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Wegener, D.; Wunsch, E.; Zacek, J.; Zhang, Z.; Zlebcik, R.; Zohrabyan, H.; Zomer, F.

    2014-01-01

    Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deep-inelastic $ep$ scattering at HERA are presented as a function of the Feynman variable $x_F$ and of the centre-of-mass energy of the virtual photon-proton system $W$. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of $131 \\mathrm{pb}^{-1}$. The measurement is restricted to photons and neutrons in the pseudorapidity range $\\eta>7.9$ and covers the range of negative four momentum transfer squared at the positron vertex $6and of $70scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections.

  13. Measurement of Feynman-x spectra of photons and neutrons in the very forward direction in deep-inelastic scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A.; Zohrabyan, H. [Yerevan Physics Institute, Yerevan (Armenia); Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Belov, P.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Dodonov, V.; Eckerlin, G.; Elsen, E.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Haidt, D.; Kleinwort, C.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Petrukhin, A.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Radescu, V.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E. [DESY, Hamburg (Germany); Boudry, V.; Specka, A. [LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France); Brandt, G. [Oxford University, Department of Physics, Oxford (United Kingdom); Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F. [LAL, Universite Paris-Sud, CNRS/IN2P3, Orsay (France); Buniatyan, A.; Huber, F.; Sauter, M.; Schoening, A. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Bylinkin, A.; Bystritskaya, L.; Fedotov, A.; Rostovtsev, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Cantun Avila, K.B.; Contreras, J.G. [CINVESTAV, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Ceccopieri, F.; Favart, L.; Grebenyuk, A.; Hreus, T.; Janssen, X.; Roosen, R.; Mechelen, P. van [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (Belgium); Cerny, K.; Pokorny, B.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R. [Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); Chekelian, V.; Grindhammer, G.; Kiesling, C. [Max-Planck-Institut fuer Physik, Munich (Germany); Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kostka, P.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Daum, K.; Meyer, H. [Fachbereich C, Universitaet Wuppertal, Wuppertal (Germany); Diaconu, C.; Hoffmann, D.; Sauvan, E.; Vallee, C. [CPPM, Aix-Marseille Univ, CNRS/IN2P3, Marseille (France); Dobre, M.; Rotaru, M. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Dossanov, A. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Max-Planck-Institut fuer Physik, Munich (Germany); Egli, S.; Horisberger, R. [Paul Scherrer Institut, Villigen (Switzerland); Feltesse, J.; Perez, E.; Schoeffel, L. [CEA, DSM/Irfu, CE-Saclay, Gif-sur-Yvette (France); Ferencei, J. [Slovak Academy of Sciences, Institute of Experimental Physics, Kosice (Slovakia); Goerlich, L.; Mikocki, S.; Nowak, G.; Sopicki, P.; Turnau, J. [Institute for Nuclear Physics, Cracow (Poland); Grab, C. [Institut fuer Teilchenphysik, ETH, Zurich (Switzerland); Henderson, R.C.W. [University of Lancaster, Department of Physics, Lancaster (United Kingdom); Herbst, M.; Schultz-Coulon, H.C. [Kirchhoff-Institut fuer Physik, Universitaet Heidelberg, Heidelberg (Germany); Hladky, J.; Reimer, P. [Academy of Sciences of the Czech Republic, Institute of Physics, Prague (Czech Republic); Jung, H. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (Belgium); DESY, Hamburg (Germany); Kapichine, M.; Lytkin, L.; Morozov, A.; Spaskov, V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kogler, R.; Nowak, K. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Landon, M.P.J.; Rizvi, E.; Traynor, D. [University of London, School of Physics and Astronomy, Queen Mary, London (GB); Lange, W.; Naumann, T. [DESY, Zeuthen (DE); Martyn, H.U. [I. Physikalisches Institut der RWTH, Aachen (DE); Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P. [Physik-Institut der Universitaet Zuerich, Zurich (CH); Newman, P.R.; Thompson, P.D. [School of Physics and Astronomy, University of Birmingham, Birmingham (GB); Picuric, I.; Raicevic, N. [University of Montenegro, Faculty of Science, Podgorica (ME); Povh, B. [Max-Planck-Institut fuer Kernphysik, Heidelberg (DE); Sankey, D.P.C. [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire (GB); Soloviev, Y. [DESY, Hamburg (DE); Lebedev Physical Institute, Moscow (RU); Stella, B. [Dipartimento di Fisica Universita di Roma Tre (IT); INFN Roma 3, Rome (IT); Sykora, T. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (BE); Charles University, Faculty of Mathematics and Physics, Prague (CZ); Tsakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (BG); Wegener, D. [Institut fuer Physik, TU Dortmund, Dortmund (DE); Collaboration: H1 Collaboration

    2014-06-15

    Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deep-inelastic ep scattering at HERA are presented as a function of the Feynman variable x{sub F} and of the centre-of-mass energy of the virtual photon-proton system W. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 131 pb{sup -1}. The measurement is restricted to photons and neutrons in the pseudorapidity range η > 7.9 and covers the range of negative four momentum transfer squared at the positron vertex 6 < Q{sup 2} < 100 GeV{sup 2}, of inelasticity 0.05 < y < 0.6 and of 70 < W < 245 GeV. To test the Feynman scaling hypothesis the W dependence of the x{sub F} dependent cross sections is investigated. Predictions of deep-inelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections. (orig.)

  14. Nonlinear propagation of a spatially incoherent laser beam: self-induced smoothing and reduction of scattering instabilities

    International Nuclear Information System (INIS)

    It is shown that plasma-induced angular spreading and spectral broadening of a spatially incoherent laser beam correspond to increased spatial and temporal incoherence of the laser light. The spatial incoherence is characterized by an effective beam f-number, decreasing in space along the direction of light propagation. Plasma-induced beam smoothing can influence laser-plasma interaction physics. In particular, decreasing the correlation time of the propagating laser light may dramatically reduce the levels of backward stimulated Brillouin and Raman scattering inside the plasma. Also, the decrease of the laser beam effective f-number reduces the reflectivity of backward stimulated Brillouin scattering. (authors)

  15. Microwave photonic filter using multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency shift

    Science.gov (United States)

    Loh, K. K.; Yeo, K. S.; Shee, Y. G.

    2015-04-01

    A microwave photonic filter based on double-Brillouin-frequency spaced multiwavelength Brillouin-erbium fiber laser (BEFL) is experimentally demonstrated. The filter selectivity can be easily adjusted by tuning and apodizing the optical taps generated from the multiwavelength BEFL. Reconfiguration of different frequency responses are demonstrated.

  16. Microwave photonic filter using multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency shift

    Energy Technology Data Exchange (ETDEWEB)

    Loh, K. K.; Yeo, K. S.; Shee, Y. G. [Integrated Lightwave Research Group, Department of Electrical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    A microwave photonic filter based on double-Brillouin-frequency spaced multiwavelength Brillouin-erbium fiber laser (BEFL) is experimentally demonstrated. The filter selectivity can be easily adjusted by tuning and apodizing the optical taps generated from the multiwavelength BEFL. Reconfiguration of different frequency responses are demonstrated.

  17. Thin-film transducers for the detection and imaging of Brillouin oscillations in transmission on cultured cells

    Science.gov (United States)

    Pérez-Cota, F.; Smith, R. J.; Moradi, E.; Webb, K.; Clark, M.

    2016-01-01

    Mechanical imaging and characterisation of biological cells has been a subject of interest for the last twenty years. Ultrasonic imaging based on the scanning acoustic microscope (SAM) and mechanical probing have been extensively reported. Large acoustic attenuation at high frequencies and the use of conventional piezo-electric transducers limit the operational frequency of a SAM. This limitation results in lower resolution compared to an optical microscope. Direct mechanical probing in the form of applied stress by contacting probes causes stress to cells and exhibits poor depth resolution. More recently, laser ultrasound has been reported to detect ultrasound in the GHz range via Brillouin oscillations on biological cells. This technique offers a promising new high resolution acoustic cell imaging technique. In this work, we propose, design and apply a thin-film based opto-acoustic transducer for the detection in transmission of Brillouin oscillations on cells. The transducer is used to generate acoustic waves, protect the cells from laser radiation and enhance signal-to-noise ratio (SNR). Experimental traces are presented in water films as well as images of the Brillouin frequency of phantom and fixed 3T3 fibroblast cells.

  18. Inelastic neutron scattering spectra of alkali metal (Na, K) bifluorides: The harmonic overtone of v3

    Science.gov (United States)

    Waddington, Thomas C.; Howard, Joseph; Brierley (in part), Keith P.; Tomkinson, John

    1982-01-01

    Inelastic neutron scattering spectra of MFHF (M  Na and K) have been measured up to energy transfers of ca. 4000 cm -1 Both 0 → 1 and 0 → 2 transitions of the bending ( v2), and antisymmetric stretching ( v3) modes were observed. A normal harmonic (i.e. no quartic contribution) model for the dynamics of the bifluoride ion is entirely consistent with our observations. Evidence of phonon dispersion was observed in the band shape of v3, but no structure attributable to the LO mode could be found. The similarity of the band shapes of v3 for both NaFHF and KFHF is interpreted in terms of a very short range coupling mechanism.

  19. Extensive HST Ultraviolet Spectra and Multi-wavelength Observations of SN 2014J in M82 Indicate Reddening and Circumstellar Scattering by Typical Dust

    CERN Document Server

    Foley, Ryan J; McCully, C; Phillips, M M; Sand, D J; Zheng, W; Challis, P; Filippenko, A V; Folatelli, G; Hillebrandt, W; Hsiao, E Y; Jha, S W; Kirshner, R P; Kromer, M; Marion, G H; Nelson, M; Pakmor, R; Pignata, G; Roepke, F K; Seitenzahl, I R; Silverman, J M; Skrutskie, M; Stritzinger, M D

    2014-01-01

    SN 2014J in M82 is the closest detected Type Ia supernova (SN Ia) in at least 28 years and perhaps in 410 years. Despite its small distance of 3.3 Mpc, SN 2014J is surprisingly faint, peaking at V = 10.6 mag, and assuming a typical SN Ia luminosity, we infer an observed visual extinction of A_V = 2.0 +/- 0.1 mag. But this picture, with R_V = 1.6 +/- 0.2, is too simple to account for all observations. We combine 10 epochs (spanning a month) of HST/STIS ultraviolet through near-infrared spectroscopy with HST/WFC3, KAIT, FanCam, and Spitzer photometry from the optical to the infrared and 9 epochs of high-resolution TRES spectroscopy to investigate the sources of extinction and reddening for SN 2014J. We argue that the wide range of observed properties for SN 2014J are caused by a combination of dust reddening, likely originating in the interstellar medium of M82, and scattering off circumstellar material. For this model, roughly half of the extinction is caused by reddening from typical dust (E(B-V) = 0.45 mag a...

  20. Scattering zippers and their spectral theory

    CERN Document Server

    Marin, Laurent

    2011-01-01

    A scattering zipper is a system obtained by concatenation of scattering events with equal even number of incoming and out going channels. The associated scattering zipper operator is the unitary equivalent of Jacobi matrices with matrix entries and generalizes Blatter-Browne and Chalker-Coddington models and CMV matrices. Weyl discs are analyzed and used to prove a bijection between the set of semi-infinite scattering zipper operators and matrix valued probability measures on the unit circle. Sturm-Liouville oscillation theory is developed as a tool to calculate the spectra of finite and periodic scattering zipper operators.

  1. Meteors and meteorites spectra

    Science.gov (United States)

    Koukal, J.; Srba, J.; Gorková, S.; Lenža, L.; Ferus, M.; Civiš, S.; Knížek, A.; Kubelík, P.; Kaiserová, T.; Váňa, P.

    2016-01-01

    The main goal of our meteor spectroscopy project is to better understand the physical and chemical properties of meteoroids. Astrometric and spectral observations of real meteors are obtained via spectroscopic CCD video systems. Processed meteor data are inserted to the EDMOND database (European viDeo MeteOr Network Database) together with spectral information. The fully analyzed atmospheric trajectory, orbit and also spectra of a Leonid meteor/meteoroid captured in November 2015 are presented as an example. At the same time, our target is the systematization of spectroscopic emission lines for the comparative analysis of meteor spectra. Meteoroid plasma was simulated in a laboratory by laser ablation of meteorites samples using an (ArF) excimer laser and the LIDB (Laser Induced Dielectric Breakdown) in a low pressure atmosphere and various gases. The induced plasma emissions were simultaneously observed with the Echelle Spectrograph and the same CCD video spectral camera as used for real meteor registration. Measurements and analysis results for few selected meteorite samples are presented and discussed.

  2. Energy spectra of small bosonic clusters having a large two-body scattering length

    CERN Document Server

    Gattobigio, M; Viviani, M

    2012-01-01

    In this work we investigate small clusters of bosons using the hyperspherical harmonic basis. We consider systems with $A=2,3,4,5,6$ particles interacting through a soft inter-particle potential. In order to make contact with a real system, we use an attractive gaussian potential that reproduces the values of the dimer binding energy and the atom-atom scattering length obtained with one of the most widely used $^4$He-$^4$He interactions, the LM2M2 potential. The intensity of the potential is varied in order to explore the clusters' spectra in different regions with large positive and large negative values of the two-body scattering length. In addition, we include a repulsive three-body force to reproduce the trimer binding energy. With this model, consisting in the sum of a two- and three-body potential, we have calculated the spectrum of the four, five and six particle systems. In all the region explored, we have found that these systems present two bound states, one deep and one shallow close to the $A-1$ t...

  3. Inelastic neutron scattering studies of phonon spectra, and simulations of pressure-induced amorphization in tungstates A W O4 (A =Ba ,Sr ,Ca , and Pb )

    Science.gov (United States)

    Goel, Prabhatasree; Gupta, M. K.; Mittal, R.; Rols, S.; Achary, S. N.; Tyagi, A. K.; Chaplot, S. L.

    2015-03-01

    Lattice dynamics and high-pressure phase transitions in A W O4 (A =Ba ,Sr ,Ca , and Pb ) have been investigated using inelastic neutron scattering experiments, ab initio density functional theory calculations, and extensive molecular dynamics simulations. The vibrational modes that are internal to W O4 tetrahedra occur at the highest energies consistent with the relative stability of W O4 tetrahedra. The neutron data and the ab initio calculations are found to be in excellent agreement. The neutron and structural data are used to develop and validate an interatomic potential model. The model is used for classical molecular dynamics simulations to study their response to high pressure. We have calculated the enthalpies of the scheelite and fergusonite phases as a function of pressure, which confirms that the scheelite to fergusonite transition is second order in nature. With increase in pressure, there is a gradual change in the A O8 polyhedra, while there is no apparent change in the W O4 tetrahedra. We found that all the four tungstates amorphize at high pressure. This is in good agreement with available experimental observations which show amorphization at around 45 GPa in BaW O4 and 40 GPa in CaW O4 . Further molecular dynamics simulations at high pressure and high temperature indicate that application of pressure at higher temperature hastens the process of amorphization. On amorphization, there is an abrupt increase in the coordination of the W atom while the bisdisphenoids around the A atom are considerably distorted. The pair-correlation functions of the various atom pairs corroborate these observations. Our observations aid in predicting the pressure of amorphization in SrW O4 and PbW O4 .

  4. Parallel heterodyne detection of dynamic light scattering spectra from gold nanoparticles diffusing in viscous fluids

    CERN Document Server

    Atlan, Michael; Gross, Michel; Coppey-Moisan, Maite; 10.1364/OL.35.000787

    2010-01-01

    We developed a microscope intended to probe, using a parallel heterodyne receiver, the fluctuation spectrum of light quasi-elastically scattered by gold nanoparticles diffusing in viscous fluids. The cutoff frequencies of the recorded spectra scale up linearly with those expected from single scattering formalism in a wide range of dynamic viscosities (1 to 15 times water viscosity at room temperature). Our scheme enables ensemble-averaged optical fluctuations measurements over multispeckle recordings in low light, at temporal frequencies up to 10 kHz, with a 12 Hz framerate array detector.

  5. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    International Nuclear Information System (INIS)

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  6. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    Institute of Scientific and Technical Information of China (English)

    Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

    2011-01-01

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of verious molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactious in the fields of biology, chemistry and naterial science.

  7. Event patterns (particle scatter plots) extracted from charged particle spectra in $pp$ and Pb-Pb collisions at 2.76 TeV

    CERN Document Server

    Chen, Ya-Hui; Fakhraddin, Sakina; Rahim, Magda A; Duan, Mai-Ying

    2016-01-01

    The transverse momentum ($p_T$) and pseudorapidity ($\\eta$) spectra of charged particles produced in proton-proton ($pp$) and lead-lead (Pb-Pb) collisions at the large hadron collider (LHC) are described by a hybrid model. In the model, the $p_T$ spectrum is described by a two-component distribution which contains an inverse power-law suggested by the QCD (Quantum Chromodynamic) calculus and an Erlang distribution resulted from a multisource thermal model. The $\\eta$ spectrum is described by a Gaussian rapidity ($y$) distribution resulted from the Landau hydrodynamic model and the two-component $p_T$ distribution, where the conversion between $y$ and $\\eta$ is accurately considered. The modelling results are in agreement with the experimental data measured by the ATLAS Collaboration in $pp$ collisions at center-of-mass energy $\\sqrt{s}=2.76$ TeV and in Pb-Pb collisions at center-of-mass energy per nucleon pair $\\sqrt{s_{NN}}=2.76$ TeV. Based on the parameter values extracted from $p_T$ and $\\eta$ or $y$ spect...

  8. Raman scattering spectra, magnetic and ferroelectric properties of BiFeO{sub 3}–CoFe{sub 2}O{sub 4} nanocomposite thin films structure

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Mintu [School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India); Kumari, Mukesh; Chatterjee, Ratnamala [Magnetics and Advanced Ceramics Laboratory, Department of Physics, Indian Institute of Technology, Delhi 110016 (India); Sharma, Puneet, E-mail: puneet.sharma@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India)

    2014-09-01

    Multiferroic (1−x)BiFeO{sub 3}(BFO)–xCoFe{sub 2}O{sub 4}(CFO) (x=0 and 0.1) nanocomposite thin films were deposited on ITO coated glass using sol–gel spin coating technique. X-ray diffraction and transmission electron microscopy examinations confirm the coexistence of both perovskite BFO and spinel CFO phases. The effect of addition of CFO in BFO matrix has been studied on Raman spectra, magnetic and ferroelectric properties. BFO/CFO nanocomposite showed good magnetic behavior (M{sub s}∼40.3 emu/cm{sup 3}, M{sub r}∼12.9 emu/cm{sup 3}, H{sub c}∼90 Oe) with no change in ferroelectric properties. The strain analysis carried out by Raman spectroscopy reveals that both BFO and CFO bands are found to be strained in BFO/CFO composite nanostructure. The strain of the bands is discussed on the basis of lattice mismatch (interfacial stress) between CFO (a=0.839 nm) and BFO (a=0.396 nm) phases.

  9. c-Axis Raman scattering spectra of MgB2: observation of a dirty-limit gap in the pi bands.

    Science.gov (United States)

    Quilty, J W; Lee, S; Tajima, S; Yamanaka, A

    2003-05-23

    Raman scattering spectra from the ac face of thick MgB2 single crystals were measured in zz, xz, and xx polarizations. In zz and xz polarizations a threshold at around 29 cm(-1) forms in the below T(c) continuum but no pair-breaking peak is seen, in contrast to the sharp pair-breaking peak at around 100 cm(-1) in xx polarization. The zz and xz spectra are consistent with Raman scattering from a dirty superconductor while the sharp peak in the xx spectra argues for a clean system. Analysis of the spectra resolves this contradiction, placing the larger and smaller gap magnitudes in the sigma and pi bands and indicating that relatively strong impurity scattering is restricted to the pi bands.

  10. Multi-wavelength Brillouin fiber laser using a holey fiber and a bismuth-oxide based erbium-doped fiber

    International Nuclear Information System (INIS)

    Multi-wavelength Brillouin fiber laser (BFL) is demonstrated using a holey fiber and a Bismuth-oxide based erbium-doped fiber (Bi-EDF) in a simple ring resonator. The proposed BFL is able to generate up to 13 lines including anti-Stokes with a channel spacing of 0.08 nm at the 1574 nm region. The multi-wavelength BFL is stable at room temperature and also compact due to the use of only a 20 m long of holey fiber and a 215 cm long of Bi-EDF

  11. Analysis of inelastic x-ray scattering spectra of low-temperature water

    Science.gov (United States)

    Liao; Chen; Sette

    2000-02-01

    We analyze a set of high-resolution inelastic x-ray scattering (IXS) spectra from H2O measured at T=259, 273, and 294 K using two different phenomenological models. Model I, called the "dynamic cage model," combines the short time in-cage dynamics described by a generalized Enskog kinetic theory with a long-time cage relaxation dynamics described by an alpha relaxation. This model is appropriate for supercooled water where the cage effect is dominant and the existence of an alpha relaxation is evident from molecular-dynamics (MD) simulation data of extended simple point charge (SPC/E) model water. Model II is essentially a generalized hydrodynamic theory called the "three effective eigenmode theory" by de Schepper et al. 11. This model is appropriate for normal liquid water where the cage effect is less prominent and there is no evidence of the alpha relaxation from the MD data. We use the model I to analyze IXS data at T=259 K (supercooled water). We successfully extract the Debye-Waller factor, the cage relaxation time from the long-time dynamics, and the dispersion relation of high-frequency sound from the short time dynamics. We then use the model II to analyze IXS data at all three temperatures, from which we are able to extract the relaxation rate of the central mode and the damping of the sound mode as well as the dispersion relation for the high-frequency sound. It turns out that the dispersion relations extracted from the two models at their respective temperatures agree with each other giving the high-frequency sound speed of 2900+/-300 m/s. This is to be compared with a slightly higher value reported previously, 3200+/-320 m/s, by analyzing similar IXS data with a phenomenological-damped harmonic oscillator model 22. This latter model has traditionally been used exclusively for the analysis of inelastic scattering spectra of water. The k-dependent sound damping and central mode relaxation rate extracted from our model analyses are compared with the known

  12. High-speed elasticity-specific nonlinear Brillouin imaging/sensing via time-resolved optical (BISTRO) measurements

    Science.gov (United States)

    Meng, Zhaokai; Ballman, Charles W.; Petrov, Georgi I.; Yakovlev, Vladislav V.

    2016-03-01

    Viscoelastic properties of living cells are often directly related to the cell types and their physiological conditions. Unfortunately, all the currently existing methods for analysis of viscoelastic properties of cells, such as micropipette aspiration, atomic force microscopy and optical tweezers are intrinsically slow, limiting their applicability to study large population of cells, which are often needed for either fundamental or clinical studies. In this report, by incorporating the concept of impulsive stimulated Brillouin scattering (ISBS), we report a Brillouin Imaging and Sensing system via Time-Resolved Optical (BISTRO) measurements. We will prove the principle of the BISTRO system by presenting example microscopic measurements and flow/cell cytometry results [1].

  13. Photon-counting Brillouin optical time-domain reflectometry based on up-conversion detector and fiber Fabry-Perot scanning interferometer

    CERN Document Server

    Xia, Haiyun; Shentu, Guoliang; Wang, Chong; Qiu, Jiawei; Xia, Xiuxiu; Chen, Chao; Zheng, Mingyang; Xie, Xiuping; Zhang, Qiang; Dou, Xiankang; Pan, Jianwei

    2015-01-01

    A direct-detection Brillouin optical time-domain reflectometry (BOTDR) is proposed and demonstrated by using an up-conversion single-photon detector and a fiber Fabry-Perot scanning interferometer (FFP-SI). Taking advantage of high signal-to-noise ratio of the detector and high spectrum resolution of the FFP-SI, the Brillouin spectrum along a polarization maintaining fiber (PMF) is recorded on a multiscaler with a small data size directly. In contrast with conventional BOTDR adopting coherent detection, photon-counting BOTDR is simpler in structure and easier in data processing. In the demonstration experiment, characteristic parameters of the Brillouin spectrum including its power, spectral width and frequency center are analyzed simultaneously along a 10 km PMF at different temperature and stain conditions.

  14. Electronic Raman scattering with excitation between localized states observed in the zinc M{sub 2,3} soft x-ray spectra of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Zn M{sub 2,3} soft x-ray fluorescence (SXF) spectra of ZnS and ZnS{sub .5}Se{sub .5} excited near threshold show strong inelastic scattering effects that can be explained using a simple model and an inelastic scattering theory based on second order perturbation theory. This scattering is often called electronic resonance Raman scattering. Tulkki and Aberg have developed this theory in detail for atomic systems, but their treatment can be applied to solid systems by utilizing electronic states characteristic of solids rather than of atomic systems.

  15. Brillouin/Raman compensation of the Kerr-effect-induced bias in a nonlinear ring laser gyroscope.

    Science.gov (United States)

    Luo, Zhang; Yuan, Xiaodong; Zhu, Zhihong; Liu, Ken; Ye, Weimin; Zeng, Chun; Ji, Jiarong

    2013-04-01

    In this Letter, the beat frequency at rest of a ring laser gyroscope with nonlinear effects is discussed in detail. Even without an additional intensity-stabilizing system, the random nullshift bias induced by the Kerr effect is compensated by the phase shift associated with the stimulated Brillouin/Raman scattering. And the nonlinear stimulated scattering also serves as the gain mechanism of the gyroscope. And thus the influence of the fluctuation of the injected pump intensity on the beat frequency is eliminated.

  16. Fast-light Enhanced Brillouin Laser Based Active Fiber Optics Sensor for Simultaneous Measurement of Rotation and Acceleration

    CERN Document Server

    Zhou, Minchuan; Fouda, Mohamed; Condon, Nicholas; Scheuer, Jacob; Shahriar, Selim M

    2016-01-01

    We have developed a conceptual design for an Active Fast Light Fiber Optic Sensor (AFLIFOS) that can perform simultaneously or separately as a gyroscope (differential mode effect) and a sensor for acceleration, strain, and other common mode effects. Two Brillouin lasers in opposite directions and separated in frequency by several free spectral ranges are used for this sensor. By coupling two auxiliary resonators to the primary fiber resonator, we produce superluminal effects for two laser modes. We develop a detailed theoretical model for optimizing the design of the AFLIFOS, and show that the enhancement factor of the sensitivity is $\\sim{187}$ and $\\sim{-187}$, respectively for the two Brillouin lasers under the optimized condition, when the effective change in perimeter of the primary fiber resonator is 0.1nm, corresponding to a rotation rate of 0.4 deg/sec for a ring resonator with radius 1m. It may be possible to get much higher enhancement by adjusting the parameters such as the perimeters and the coupl...

  17. The mixed Wentzel–Kramers–Brillouin-full-wave approach and its application to lower hybrid wave propagation and absorption

    International Nuclear Information System (INIS)

    The mixed Wentzel–Kramers–Brillouin (WKB)-full-wave approach for the calculation of the 2D mode structure in tokamak plasmas is further developed based on our previous work [A. Cardinali and F. Zonca, Phys. Plasmas 10, 4199 (2003) and Z. X. Lu et al., Phys. Plasmas 19, 042104 (2012)]. A new scheme for theoretical analysis and numerical implementation of the mixed WKB-full-wave approach is formulated, based on scale separation and asymptotic analysis. Besides its capability to efficiently investigate the initial value problem for 2D mode structures and linear stability, in this work, the mixed WKB-full-wave approach is extended to the investigation of radio frequency wave propagation and absorption, e.g., lower hybrid waves. As a novel method, its comparison with other approaches, e.g., WKB and beam tracing methods, is discussed. Its application to lower hybrid wave propagation in concentric circular tokamak plasmas using typical FTU discharge parameters is also demonstrated.

  18. Onset of the alpha-relaxation in the glass-forming solution LiCl-6H2O revealed by Brillouin scattering techniques.

    Science.gov (United States)

    Santucci, S C; Comez, L; Scarponi, F; Monaco, G; Verbeni, R; Legrand, J-F; Masciovecchio, C; Gessini, A; Fioretto, D

    2009-10-21

    We measured the dynamic structure factor of the liquid and glassy phases of the LiCl-6H(2)O solution by means of inelastic scattering of radiation in the visible, UV, and x-ray range, between 1 GHz and 10 THz, and by means of photon-correlation spectroscopy, between 0.01 Hz and 20 kHz. The measurements were performed in the temperature range between 353 and 80 K. Our data show that a single-relaxation process exists at high temperature, which has features similar to those of the single relaxation of pure water. Upon cooling the system below approximately 220 K, this single mode starts to differentiate two processes, a structural (alpha-) and a secondary (beta-) relaxation. As the temperature is decreased, the beta-relaxation is the vanishing continuation of the single, high-temperature process, while the onset of the alpha-relaxation occurs at the expense of the beta-process. PMID:20568872

  19. Brillouin resonance broadening due to structural variations in nanoscale waveguides

    CERN Document Server

    Wolff, Christian; Steel, Michael J; Eggleton, Benjamin J; Poulton, Christopher G

    2015-01-01

    We study the impact of structural variations (that is slowly varying geometry aberrations and internal strain fields) on the resonance width and shape of stimulated Brillouin scattering (SBS) in nanoscale waveguides. We find that they lead to an inhomogeneous resonance broadening through two distinct mechanisms: firstly, the acoustic frequency is directly influenced via mechanical nonlinearities; secondly, the optical wave numbers are influenced via the opto-mechanical nonlinearity leading to an additional acoustic frequency shift via the phase-matching condition. We find that this second mechanism is proportional to the opto-mechanical coupling and, hence, related to the SBS-gain itself. It is absent in intra-mode forward SBS, while it plays a significant role in backward scattering. In backward SBS increasing the opto-acoustic overlap beyond a threshold defined by the fabrication tolerances will therefore no longer yield the expected quadratic increase in overall Stokes amplification. Our results can be tra...

  20. Dynamics of H2 adsorbed in porous materials as revealed by computational analysis of inelastic neutron scattering spectra.

    Science.gov (United States)

    Pham, Tony; Forrest, Katherine A; Space, Brian; Eckert, Juergen

    2016-06-29

    The inelastic scattering of neutrons from adsorbed H2 is an effective and highly sensitive method for obtaining molecular level information on the type and nature of H2 binding sites in porous materials. While these inelastic neutron scattering (INS) spectra of the hindered rotational and translational excitations on the adsorbed H2 contain a significant amount of information, much of this can only be reliably extracted by means of a detailed analysis of the spectra through the utilization of models and theoretical calculations. For instance, the rotational tunneling transitions observed in the INS spectra can be related to a value for the barrier to rotation for the adsorbed H2 with the use of a simple phenomenological model. Since such an analysis is dependent on the model, it is far more desirable to use theoretical methods to compute a potential energy surface (PES), from which the rotational barriers for H2 adsorbed at a particular site can be determined. Rotational energy levels and transitions for the hindered rotor can be obtained by quantum dynamics calculations and compared directly with experiment with an accuracy subject only to the quality of the theoretical PES. In this paper, we review some of the quantum and classical mechanical calculations that have been performed on H2 adsorbed in various porous materials, such as clathrate hydrates, zeolites, and metal-organic frameworks (MOFs). The principal aims of these calculations have been the interpretation of the INS spectra for adsorbed H2 along with the extraction of atomic level details of its interaction with the host. We describe calculations of the PES used for two-dimensional quantum rotation as well as rigorous five-dimensional quantum coupled translation-rotation dynamics, and demonstrate that the combination of INS measurements and computational modeling can provide important and detailed insights into the molecular mechanism of H2 adsorption in porous materials. PMID:27160665

  1. Irreducible Brillouin conditions and contracted Schroedinger equations for n-electron systems. IV. Perturbative analysis

    International Nuclear Information System (INIS)

    The k-particle irreducible Brillouin conditions IBCk and the k-particle irreducible contracted Schroedinger equations ICSEk for a closed-shell state are analyzed in terms of a Moeller-Plesset-type perturbation expansion. The zeroth order is Hartree-Fock. From the IBC2(1), i.e., from the two-particle IBC to first order in the perturbation parameter μ, one gets the leading correction λ2(1) to the two-particle cumulant λ2 correctly. However, in order to construct the second-order energy E2, one also needs the second-order diagonal correction γD(2) to the one-particle density matrix γ. This can be obtained: (i) from the idempotency of the n-particle density matrix, i.e., essentially from the requirement of n-representability; (ii) from the ICSE1(2); or (iii) by means of perturbation theory via a unitary transformation in Fock space. Method (ii) is very unsatisfactory, because one must first solve the ICSE3(2) to get λ3(2), which is needed in the ICSE2(2) to get λ2(2), which, in turn, is needed in the ICSE1(2) to get γ(2). Generally the (k+1)-particle approximation is needed to obtain Ek correctly. One gains something, if one replaces the standard hierarchy, in which one solves the ICSEk, ignoring λk+1 and λk+2, by a renormalized hierarchy, in which only λk+2 is ignored, and λk+1 is expressed in terms of the λp of lower particle rank via the partial trace relation for λk+2. Then the k-particle approximation is needed to obtain Ek correctly. This is still poorer than coupled-cluster theory, where the k-particle approximation yields Ek+1. We also study the possibility to use some simple necessary n-representability conditions, based on the non-negativity of γ(2) and two related matrices, in order to get estimates for γD(2) in terms of λ2(1). In general these estimates are rather weak, but they can become close to the best possible bounds in special situations characterized by a very sparse structure of λ2 in terms of a localized representation. The

  2. Classification and radiative-transfer modeling of meteorite spectra

    Science.gov (United States)

    Pentikäinen, H.; Penttilä, A.; Peltoniemi, J.; Muinonen, K.

    2014-07-01

    The interpretation of asteroid spectra is closely tied to surface structure and composition. Asteroid surfaces are usually assumed to be covered with a regolith, which is a mixture of mineral grains ranging from micrometers to centimeters in size. The inverse problem of deducing the characteristics of the grains from the scattering of light (e.g., using photometric and polarimetric observations) is difficult. Meteorite spectroscopy can be a valuable alternative source of information considering that unweathered meteoritic ''falls'' are almost pristine samples of their parent bodies. Reflectance spectra of 18 different meteorite samples were measured with the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO) covering a wavelength range of 450--2250 nm [1,2]. The measurements expand the database of reflectance spectra obtained by Paton et al. [3] and Gaffey [4]. Principal Component Analysis (PCA) performed on the spectra indicates a separation of the undifferentiated ordinary chondrites and the differentiated achondrites. The principal components also suggest a discrimination between the spectra of ordinary chondrites with petrologic grades 5 and 6. The distinction is not present when the data are supplemented with the spectra from the two other data sets obtained with differing measuring techniques. To further investigate the different classifications, the PCA is implemented with selected spectral features contrary to the previous analyses, which encompassed the complete spectra. Single-scattering albedos for meteoritic fundamental scatterers were derived with a Monte Carlo radiative-transfer model [1]. In the derivation, realistic scattering phase functions were utilized. The functions were obtained by fitting triple Henyey-Greenstein functions to the measured scattering phase functions of olivine powder for two different size distributions [5,6]. The simulated reflectances for different scattering phase functions were matched to the measured meteorite

  3. Co/Ti金属磁性多层膜的激光布里渊散射研究%Co/Ti magnetic multilayer films investigated by Brillouin light scattering

    Institute of Scientific and Technical Information of China (English)

    刘玉龙; 萧季驹

    2002-01-01

    在室温下利用直流磁控溅射法制备出了具有不同Co层厚度的[Co(dco nm)/Ti(dTi nm)].金属磁性多层膜(其中dcoand dTi是Co和TI\\i的厚度,n薄膜调制周期数).在300K下用X射线衍射法(XRD)和布里渊散射方法研究了Co层厚度分别为dco=1,2,2.5,3.5 nm,Ti层厚度为dTi=2.5 nm的Co/Ti多层膜.XRD的结果所示在Co/Ti多层膜中Co层厚度超过2.5 nm,其结构类似块材Co的多晶结构.对比之下,Co/Ti多层膜中Co层厚度低于2.5 nm,其XRD衍射峰随Co层厚度减少变的峰形加宽,衍射峰的强度减少,峰位移动和消失.在Co/Ti多层膜中自旋波的布里渊散射结果表明:在Co/Ti多层膜中,对于dco>2.5nm磁性呈铁磁性耦合,在dco≤2.5 nm时,其呈反铁磁性耦合.除表面自旋波外,在呈反铁磁性耦合的材料中观测到了两个有体特征的自旋波,而在呈铁磁耦合的材料中只观测到一个有体特征的自旋波.%[Co(dConm)/Ti(dTinm) ]n(both dCo and dTi are the thicknesses of Co and Ti sublayers, re-spectively. n is the number- of modulation periods. ) magnetic multilayer films (MMLFs) with differentCo sublayer thicknesses are prepared at room temperature by the dc magnetron sputtering technique.Co/Ti MMLFs (dco = 1,2, 2.5 and 3.5 nm, dTi = 2.5 nm) are investigated using x-ray diffraction(XRD) and Brillouin light scattering (BLS) from spin waves at 300 K. XRD of the MMLFs with Cosublayer thicknesses exceeding 2.5 nm are similar to the polycrystalline structures of bulk Co. On thecontrary, those of the films with Co sublayer thicknesses below 2.5 nm are deteriorated crystallinespectra with spectriscopic peak broadening, peak intensity reducing, position shifting and merging.BLD results from spin waves in Co/Ti MMlfs show ferromagnetic coupling for dco >2.5 nm, and antifearomagnetic coupling between adjacent Co layers for dco ≤2.5 nm. Besids a surface-character spinwave, two bulk-character spin wave bands are observed for antiferromagnetic films, but only

  4. Light scattering studies of solids and atomic vapors

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, T.C.

    1978-09-01

    The general technique of light scattering and luminescence was used to study the properties of a number of material systems. First, multi-phonon resonant Raman scattering up to four phonons in GaSe and one- and two-phonon resonant Raman scattering in the mixed GaS/sub x/Se/sub 1-x/ crystals with x < or = 0.23 were investigated. Second, the observation of one-phonon resonant Raman scattering in HfS/sub 2/ is reported. The result is used to determine the position of the direct gap of HfS/sub 2/. Third, the first observation of the ..pi..-polarized one-magnon luminescence sideband of the /sup 4/T/sub lg/ (/sup 4/G) ..-->.. /sup 6/A/sub lg/(/sup 6/S) excitonic transition in antiferromagnetic MnF/sub 2/ is presented. An effective temperature of the crystal is deduced from the simultaneously observed anti-Stokes sideband emission. Multi-magnon (< or = 7) excitonic luminescence sidebands were also observed in MnF/sub 2/, KMnF/sub 2/, and RbMnF/sub 3/ using pulsed excitation and detection. A simple model based on two-ion local exchange is proposed to explain the results qualitatively. Fourth, the first observation of two-magnon resonant Raman scattering in MnF/sub 2/ around the magnon sidebands is reported. A simple theoretical description explains the experimental observations. Fifth, a detailed theory of exciton-exciton interaction in MnF/sub 2/ is developed to explain and to predict the experimental results on two-exciton absorption, high level excitation, and exciton--exciton scattering. Sixth, Brillouin scattering was used to obtain the five independent elastic constants of the layered compound GaSe. The results show clear elastic anisotropy of the crystal. Resonant Brillouin scattering near the absorption edge was also studied, but no resonant enhancement was found. Seventh, two-photon parametric scattering in sodium vapor was studied. Phase matching angles and scattering cross sections are calculated for a given set of experimental conditions.

  5. Polarized Scattering and Biosignatures in Exoplanetary Atmospheres

    CERN Document Server

    Berdyugina, S V

    2016-01-01

    Polarized scattering in planetary atmospheres is computed in the context of exoplanets. The problem of polarized radiative transfer is solved for a general case of absorption and scattering, while Rayleigh and Mie polarized scattering are considered as most relevant examples. We show that (1) relative contributions of single and multiple scattering depend on the stellar irradiation and opacities in the planetary atmosphere; (2) cloud (particle) physical parameters can be deduced from the wavelength-dependent measurements of the continuum polarization and from a differential analysis of molecular band absorption; (3) polarized scattering in molecular bands increases the reliability of their detections in exoplanets; (4) photosynthetic life can be detected on other planets in visible polarized spectra with high sensitivity. These examples demonstrate the power of spectropolarimetry for exoplanetary research and for searching for life in the universe.

  6. [The High Precision Analysis Research of Multichannel BOTDR Scattering Spectral Information Based on the TTDF and CNS Algorithm].

    Science.gov (United States)

    Zhang, Yan-jun; Liu, Wen-zhe; Fu, Xing-hu; Bi, Wei-hong

    2015-07-01

    Traditional BOTDR optical fiber sensing system uses single channel sensing fiber to measure the information features. Uncontrolled factors such as cross-sensitivity can lead to a lower scattering spectrum fitting precision and make the information analysis deflection get worse. Therefore, a BOTDR system for detecting the multichannel sensor information at the same time is proposed. Also it provides a scattering spectrum analysis method for multichannel Brillouin optical time-domain reflection (BOT-DR) sensing system in order to extract high precision spectrum feature. This method combines the three times data fusion (TTDF) and the cuckoo Newton search (CNS) algorithm. First, according to the rule of Dixon and Grubbs criteria, the method uses the ability of TTDF algorithm in data fusion to eliminate the influence of abnormal value and reduce the error signal. Second, it uses the Cuckoo Newton search algorithm to improve the spectrum fitting and enhance the accuracy of Brillouin scattering spectrum information analysis. We can obtain the global optimal solution by smart cuckoo search. By using the optimal solution as the initial value of Newton algorithm for local optimization, it can ensure the spectrum fitting precision. The information extraction at different linewidths is analyzed in temperature information scattering spectrum under the condition of linear weight ratio of 1:9. The variances of the multichannel data fusion is about 0.0030, the center frequency of scattering spectrum is 11.213 GHz and the temperature error is less than 0.15 K. Theoretical analysis and simulation results show that the algorithm can be used in multichannel distributed optical fiber sensing system based on Brillouin optical time domain reflection. It can improve the accuracy of multichannel sensing signals and the precision of Brillouin scattering spectrum analysis effectively. PMID:26717729

  7. Phase-locking in Multi-Frequency Brillouin Oscillator via Four Wave Mixing

    CERN Document Server

    Buettner, Thomas F S; Hudson, Darren D; Pant, Ravi; Poulton, Christopher G; Judge, Alexander C; Eggleton, Benjamin J

    2014-01-01

    Stimulated Brillouin scattering (SBS) and Kerr-nonlinear four wave-mixing (FWM) are among the most important and widely studied nonlinear effects in optical fibres. At high powers SBS can be cascaded producing multiple Stokes waves spaced by the Brillouin frequency shift. Here, we investigate the complex nonlinear interaction of the cascade of Stokes waves, generated in a Fabry-Perot chalcogenide fibre resonator through the combined action of SBS and FWM. We demonstrate the existence of parameter regimes, in which pump and Stokes waves attain a phase-locked steady state. Real-time measurements of 40ps pulses with 8GHz repetition rate are presented, confirming short-and long-term stability. Numerical simulations qualitatively agree with experiments and show the significance of FWM in phase-locking of pump and Stokes waves. Our findings can be applied for the design of novel picosecond pulse sources with GHz repetition rate for optical communication systems.

  8. Towards the estimation of the scattered energy spectra reaching the head of the medical staff during interventional radiology: A Monte Carlo simulation study

    Science.gov (United States)

    Zagorska, A.; Bliznakova, K.; Buchakliev, Z.

    2015-09-01

    In 2012, the International Commission on Radiological Protection has recommended a reduction of the dose limits to the eye lens for occupational exposure. Recent studies showed that in interventional rooms is possible to reach these limits especially without using protective equipment. The aim of this study was to calculate the scattered energy spectra distribution at the level of the operator's head. For this purpose, an in-house developed Monte Carlo-based computer application was used to design computational phantoms (patient and operator), the acquisition geometry as well as to simulate the photon transport through the designed system. The initial spectra from 70 kV tube voltage and 8 different filtrations were calculated according to the IPEM Report 78. An experimental study was carried out to verify the results from the simulations. The calculated scattered radiation distributions were compared to the initial incident on the patient spectra. Results showed that there is no large difference between the effective energies of the scattered spectra registered in front of the operator's head obtained from simulations of all 8 incident spectra. The results from the experimental study agreed well to simulations as well.

  9. Determination of the fast neutrons spectra by the Elastic scattering method (n, p)

    CERN Document Server

    Elizalde, J

    1973-01-01

    This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spect...

  10. Correlation Functions and Power Spectra

    DEFF Research Database (Denmark)

    Larsen, Jan

    2006-01-01

    The present lecture note is a supplement to the textbook Digital Signal Processing by J. Proakis and D.G. Manolakis used in the IMM/DTU course 02451 Digital Signal Processing and provides an extended discussion of correlation functions and power spectra. The definitions of correlation functions...

  11. Proton-transfer dynamics in the hydrogen bond. Inelastic neutron scattering, infrared and Raman spectra of KH(CF 3COO) 2 and CsH(CF 3COO) 2

    Science.gov (United States)

    Fillaux, F.; Tomkinson, J.

    1991-12-01

    Inelastic neutron scattering (INS), infrared and Raman spectra of potassium and cesium hydrogen bistrifluoroacetate (KH(CF 3COO) 2 and CsH(CF 3COO) 2, respectively) at 20 K are reported. In both crystals H(CF 3COO) 2- centrosymmetric dimers are linked by strong hydrogen bonds, whose lengths are 2.435 and 2.38 Å, respectively. The principal OH modes appear at the same frequencies for both compounds. The OH stretching band shapes are similar in infrared and in INS. The submaxima are attributed to interactions with other internal modes. Below 200 cm -1, the cesium salt shows three narrow bands which emerge from the density-of-states. They are assigned to localized modes involving the proton. A sharp band at 87 cm -1 corresponds to the "tunnelling" transition in a quasi-symmetric double-minimum potential with a barrier height of 1340 cm -1. The other two narrow bands, at 36 and 49 cm -1, are assigned to the internal torsions of coupled CF 3COO groups. Potential barriers are estimated. A detailed band-shape analysis of the OH bending modes provides clear indications of different dynamics for the two salts. KH(CF 3COO) 2 is rather stiff and phonon wings involving the whole lattice density-of-states are observed for the δOH mode but not for the γOH mode. For this latter, the observed combinations indicate a dynamical coupling with the internal torsion. CsH(CF 3COO) 2 is rather soft and recoil occurs. The INS intensities of the OH bending modes are decreased by Debye-Waller factors and their frequencies are shifted upwards. The estimated masses of the recoiling particles are consistent with strong dynamical coupling of the γOH with the torsional mode on the one hand, and of the δOH with translational modes on the other. The polarizability of the counter ion appears to play a leading role in proton dynamics.

  12. Stratospheric aerosol particle size information in Odin-OSIRIS limb scatter spectra

    Science.gov (United States)

    Rieger, L. A.; Bourassa, A. E.; Degenstein, D. A.

    2014-02-01

    The Optical Spectrograph and InfraRed Imaging System (OSIRIS) onboard the Odin satellite has now taken over a decade of limb scatter measurements that have been used to retrieve the version 5 stratospheric aerosol extinction product. This product is retrieved using a representative particle size distribution to calculate scattering cross sections and scattering phase functions for the forward model calculations. In this work the information content of OSIRIS measurements with respect to stratospheric aerosol is systematically examined for the purpose of retrieving particle size information along with the extinction coefficient. The benefit of using measurements at different wavelengths and scattering angles in the retrieval is studied, and it is found that incorporation of the 1530 nm radiance measurement is key for a robust retrieval of particle size information. It is also found that using OSIRIS measurements at the different solar geometries available on the Odin orbit simultaneously provides little additional benefit. Based on these results, an improved aerosol retrieval algorithm is developed that couples the retrieval of aerosol extinction and mode radius of a log-normal particle size distribution. Comparison of these results with coincident measurements from SAGE III shows agreement in retrieved extinction to within approximately 10% over the bulk of the aerosol layer, which is comparable to version 5. The retrieved particle size, when converted to Ångström coefficient, shows good qualitative agreement with SAGE II measurements made at somewhat shorter wavelengths.

  13. Resolving the bulk ion region of millimeter-wave collective Thomson scattering spectra at ASDEX Upgrade

    DEFF Research Database (Denmark)

    Stejner Pedersen, Morten; Nielsen, Stefan Kragh; Jacobsen, Asger Schou;

    2014-01-01

    resolution in the range of 1 MHz are then obtained through direct digitization and Fourier analysis of the CTS signal. We here describe the design, calibration, and operation of the fast receiver system and give examples of measured bulk ion CTS spectra showing the effects of changing ion temperature...

  14. Polynomial analysis of canopy spectra and biochemical component content inversion

    Institute of Scientific and Technical Information of China (English)

    YAN Chunyan; LIU Qiang; NIU Zheng; WANG Jihua; HUANG Wenjiang; LIU Liangyun

    2005-01-01

    A polynomial expression model was developed in this paper to describe directional canopy spectra, and the decomposition of the polynomial expression was used as a tool for retrieving biochemical component content from canopy multi-angle spectra. First, the basic formula of the polynomial expression was introduced and the physical meaning of its terms and coefficients was discussed. Based on this analysis, a complete polynomial expression model and its decomposition method were given. By decomposing the canopy spectra simulated with SAILH model, it shows that the polynomial expression can not only fit well the canopy spectra, but also show the contribution of every order scattering to the whole reflectance. Taking the first scattering coefficients a10 and a01 for example, the test results show that the polynomial coefficients reflect very well the hot spot phenomenon and the effects of viewing angles, LAI and leaf inclination angle on canopy spectra. By coupling the polynomial expression with leaf model PROSPECT, a canopy biochemical component content inversion model was given. In the simulated test, the canopy multi-angle spectra were simulated by two different models, SAILH and 4-SCALE respectively, then the biochemical component content was retrieved by inverting the coupled polynomial expression + PROSPECT model. Results of the simulated test are promising, and when applying the algorithm to measured corn canopy multi-angle spectra, we also get relatively accurate chlorophyll content. It shows that the polynomial analysis provides a new method to get biochemical component content independent of any specific canopy model.

  15. Dual-microcavity narrow-linewidth Brillouin laser

    CERN Document Server

    Loh, William; Baynes, Frederick; Cole, Daniel; Quinlan, Franklyn; Lee, Hansuek; Vahala, Kerry; Papp, Scott; Diddams, Scott

    2014-01-01

    Ultralow noise, yet tunable lasers are a revolutionary tool in precision spectroscopy, displacement measurements at the standard quantum limit, and the development of advanced optical atomic clocks. Further applications include LIDAR, coherent communications, frequency synthesis, and precision sensors of strain, motion, and temperature. While all applications benefit from lower frequency noise, many also require a laser that is robust and compact. Here, we introduce a dual-microcavity laser that leverages one chip-integrable silica microresonator to generate tunable 1550 nm laser light via stimulated Brillouin scattering (SBS) and a second microresonator for frequency stabilization of the SBS light. This configuration reduces the fractional frequency noise to $7.8\\times10^{-14} 1/\\sqrt{Hz}$ at 10 Hz offset, which is a new regime of noise performance for a microresonator-based laser. Our system also features terahertz tunability and the potential for chip-level integration. We demonstrate the utility of our du...

  16. Brillouin lasing in whispering gallery micro-resonators

    Science.gov (United States)

    Sturman, B.; Breunig, I.

    2015-12-01

    Thresholds of stimulated Brillouin scattering (SBS) in solid-state whispering gallery mode (WGM) microresonators are analyzed. It is shown that the SBS interaction is substantially different here from that known in the bulk case and in the case of water droplet resonators. The reason is the absence of pure longitudinal acoustic WGMs owing to strong coupling of the longitudinal (l) and transverse (t) acoustic displacements at the surface of the resonator. As a result, a considerable increase of the SBS thresholds takes place, and the lowest thresholds correspond to the hybrid tl-modes with very large radial indices. Nevertheless, the thresholds lie in the μW range of the pump power. Dependence of the SBS power thresholds on the modal numbers and the possibility of self-tuning to the SBS resonance are analyzed.

  17. High spatial resolution, dynamic, and distributed fiber optic strain sensing based on phasorial Brillouin dynamic gratings reflectometry

    Science.gov (United States)

    Bergman, A.; Langer, T.; Tur, M.

    2016-05-01

    We present a novel fiber-optic sensing technique based on the distributed measurement of Brillouin-induced phase-shift in the reflection from Brillouin dynamic gratings in polarization-maintaining fibers. Subject to signal to noise considerations, the strain sensitivity of the phase-shift in the reflection of a pulsed probe, orthogonally polarized to the gratings-generating pumps, is independent of the pulse width, suggesting the potential to achieve higher spatial resolutions than those offered by slope-assisted, phasorial Brillouin sensing techniques in standard single-mode fibers. We report the measurement of 500Hz strain vibrations (at a sampling rate of 1MHz) with a spatial resolution of 20cm.

  18. Tunable millimeter-wave frequency synthesis up to 100 GHz by dual-wavelength Brillouin fiber laser.

    Science.gov (United States)

    Gross, Michael C; Callahan, Patrick T; Clark, Thomas R; Novak, Dalma; Waterhouse, Rodney B; Dennis, Michael L

    2010-06-21

    We demonstrate the generation of microwave and millimeter-wave frequencies from 26 to 100 GHz by heterodyning the output modes of a dual-wavelength fiber laser based on stimulated Brillouin scattering. The output frequency is tunable in steps of 10.3 MHz, equal to the free spectral range of the resonator. The noise properties of the beat frequency indicate a microwave linewidth of <2 Hz. We discuss potential for operation into the terahertz regime.

  19. Beyond the Brillouin limit with the Penning Fusion Experiment

    International Nuclear Information System (INIS)

    Several years ago, it was proposed that a dense non-neutral plasma could be produced in a Penning trap. Nonneutral plasmas have excellent confinement, and such a dense plasma might produce simultaneously high density and good confinement. Recently, this theoretical conjecture has been demonstrated in a small (3 mm radius) electron experiment, PFX (Penning Fusion Experiment). Densities up to 35 times the Brillouin density (limiting number density in a static trap) have been inferred from the observed strong (100:1) spherical focusing. Electrons are injected at low energy from a single pole of the sphere. A surprising observation is the self-organization of the system into a spherical state, which occurs precisely when the trap parameters are adjusted to produce a spherical well. This organization is caused by a bootstrapping mechanism which produces a hysteresis. Observations of energy-scattered electrons confirm the existence of a dense spherical focus. copyright 1997 American Institute of Physics

  20. Diffusive properties of water in Artemia cysts as determined from quasi-elastic neutron scattering spectra. [Artemia shrimp

    Energy Technology Data Exchange (ETDEWEB)

    Trantham, E.C.; Rorschach, H.E.; Clegg, J.S.; Hazlewood, C.F.; Nicklow, R.M.; Wakabayashi, N.

    1984-05-01

    Results have been obtained on the quasi-elastic spectra of neutrons scattered from pure water, 20% agarose gel (hydration four grams H/sub 2/O per gram of dry solid) and cysts of the brine shrimp Artemia for hydrations between 0.10 and 1.2 grams H/sub 2/O per gram of dry solids. The spectra were interpreted using a two-component model that included contributions from the covalently bonded protons and the hydration water, and a mobile water fraction. The mobile fraction was described by a jump-diffusion correlation function for the translation motion and a simple diffusive orientational correlation function. The results for the line widths ..gamma..(Q/sup 2/) for pure water were in good agreement with previous measurements. The agarose results were consistent with NMR measurements that show a slightly reduced translational diffusion for the mobile water fraction. The Artemia results show that the translational diffusion coefficient of the mobile water fraction was greatly reduced from that of pure water. The line width was determined mainly by the rotational motion, which was also substantially reduced from the pure water value as determined from dielectric relaxation studies. The translational and rotational diffusion parameters were consistent with the NMR measurements of diffusion and relaxation. Values for the hydration fraction and the mean square thermal displacement as determined from the Q-dependence of line areas were also obtained.

  1. BPS Spectra, Barcodes and Walls

    CERN Document Server

    Cirafici, Michele

    2015-01-01

    BPS spectra give important insights into the non-perturbative regimes of supersymmetric theories. Often from the study of BPS states one can infer properties of the geometrical or algebraic structures underlying such theories. In this paper we approach this problem from the perspective of persistent homology. Persistent homology is at the base of topological data analysis, which aims at extracting topological features out of a set of points. We use these techniques to investigate the topological properties which characterize the spectra of several supersymmetric models in field and string theory. We discuss how such features change upon crossing walls of marginal stability in a few examples. Then we look at the topological properties of the distributions of BPS invariants in string compactifications on compact threefolds, used to engineer black hole microstates. Finally we discuss the interplay between persistent homology and modularity by considering certain number theoretical functions used to count dyons i...

  2. Collective Excitations in Liquid Hydrogen Observed by Coherent Neutron Scattering

    DEFF Research Database (Denmark)

    da Costa Carneiro, Kim; Nielsen, M.; McTague, J. P.

    1973-01-01

    Coherent scattering of neutrons by liquid parahydrogen shows the existence of well-defined collective excitations in this liquid. Qualitative similarity with the scattering from liquid helium is found. Furthermore, in the range of observed wave vectors, 0.7 Å-1 ≤κ≤3.1 Å-1, extending from the first...... through the third Brillouin zones in the solid, S(κ,ω) is remarkably similar to the scattering law expected from a polycrystal. For κ≤2.3 Å-1 the observed spectra satisfy the one-phonon sum rule with mean square displacement 〈u2〉=1.0 Å2....

  3. Optical-scattering measurements from 1.06-μm, 0.53-μm, and 0.35-μm laser-heated disk targets

    International Nuclear Information System (INIS)

    A discussion is presented on scattered light measurements relevant to three of the important parametric instabilities which occur in high intensity laser plasma interactions: stimulated Brillouin scattering (SBS), the two plasmon decay instability (2-ω/sub pe/), and stimulated Raman scattering (SRS). Most of these experiments were carried out on the ARGUS facility. Its configuration is described for the multiple wavelength experiments, all of which were conducted with one beam illumination of flat disk targets

  4. Naturally enhanced ion-acoustic spectra and their interpretation

    DEFF Research Database (Denmark)

    Sedgemore-Schulthess, K.J.F.; St. Maurice, J.P.

    2001-01-01

    Incoherent scatter radars are designed to detect scatter from thermal fluctuations in the ionosphere. These fluctuations contain, among other things, features associated with ion-acoustic waves driven by random motions within the plasma. The resulting spectra are generally broad and noisy, but...... nevertheless the technique can, through a detailed analysis of spectra, be used to measure a range of physical parameters in the Earth's upper atmosphere, and provides a powerful diagnostic in studies of magnetosphere-ionosphere coupling, thermosphere dynamics and the geospace environment in general. In recent...... acceleration, wave-particle and wave-wave interactions in the ionosphere, and their association with magnetospheric processes. There is now a substantial body of literature documenting observations of enhanced ion-acoustic spectra, but there remains controversy over generation mechanisms. We present a review...

  5. Sharp low-energy feature in single-particle spectra due to forward scattering in d-wave cuprate superconductors.

    Science.gov (United States)

    Hong, Seung Hwan; Bok, Jin Mo; Zhang, Wentao; He, Junfeng; Zhou, X J; Varma, C M; Choi, Han-Yong

    2014-08-01

    There is an enormous interest in the renormalization of the quasiparticle (qp) dispersion relation of cuprate superconductors both below and above the critical temperature T_{c} because it enables the determination of the fluctuation spectrum to which the qp's are coupled. A remarkable discovery by angle-resolved photoemission spectroscopy (ARPES) is a sharp low-energy feature (LEF) in qp spectra well below the superconducting energy gap but with its energy increasing in proportion to T_{c} and its intensity increasing sharply below T_{c}. This unexpected feature needs to be reconciled with d-wave superconductivity. Here, we present a quantitative analysis of ARPES data from Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi2212) using Eliashberg equations to show that the qp scattering rate due to the forward scattering impurities far from the Cu-O planes is modified by the energy gap below T_{c} and shows up as the LEF. This is also a necessary step to analyze ARPES data to reveal the spectrum of fluctuations promoting superconductivity. PMID:25126930

  6. Sharp low-energy feature in single-particle spectra due to forward scattering in d-wave cuprate superconductors.

    Science.gov (United States)

    Hong, Seung Hwan; Bok, Jin Mo; Zhang, Wentao; He, Junfeng; Zhou, X J; Varma, C M; Choi, Han-Yong

    2014-08-01

    There is an enormous interest in the renormalization of the quasiparticle (qp) dispersion relation of cuprate superconductors both below and above the critical temperature T_{c} because it enables the determination of the fluctuation spectrum to which the qp's are coupled. A remarkable discovery by angle-resolved photoemission spectroscopy (ARPES) is a sharp low-energy feature (LEF) in qp spectra well below the superconducting energy gap but with its energy increasing in proportion to T_{c} and its intensity increasing sharply below T_{c}. This unexpected feature needs to be reconciled with d-wave superconductivity. Here, we present a quantitative analysis of ARPES data from Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi2212) using Eliashberg equations to show that the qp scattering rate due to the forward scattering impurities far from the Cu-O planes is modified by the energy gap below T_{c} and shows up as the LEF. This is also a necessary step to analyze ARPES data to reveal the spectrum of fluctuations promoting superconductivity.

  7. Ultralow-threshold cascaded Brillouin microlaser for tunable microwave generation.

    Science.gov (United States)

    Guo, Changlei; Che, Kaijun; Cai, Zhiping; Liu, Shuai; Gu, Guoqiang; Chu, Chengxu; Zhang, Pan; Fu, Hongyan; Luo, Zhengqian; Xu, Huiying

    2015-11-01

    We experimentally demonstrate an ultralow-threshold cascaded Brillouin microlaser for tunable microwave generation in a high-Q silica microsphere resonator. The threshold of the Brillouin microlaser is as low as 8 μW, which is close to the theoretical prediction. Moreover, the fifth-order Stokes line with a frequency shift up to 55 GHz is achieved with a coupled pump power of less than 0.6 mW. Benefiting from resonant wavelength shifts driven by thermal dynamics in the microsphere, we further realized tunable microwave signals with tuning ranges of 40 MHz at an 11 GHz band and 20 MHz at a 22 GHz band. To the best of our knowledge, it was the first attempt for tunable microwave source based on the whispering-gallery-mode Brillouin microlaser. Such a tunable microwave source from a cascaded Brillouin microlaser could find significant applications in aerospace, communication engineering, and metrology.

  8. Resonant Raman scattering theory for Kitaev models and their Majorana fermion boundary modes

    Science.gov (United States)

    Perreault, Brent; Knolle, Johannes; Perkins, Natalia B.; Burnell, F. J.

    2016-09-01

    We study the inelastic light scattering response in two- (2D) and three-dimensional (3D) Kitaev spin-liquid models with Majorana spinon band structures in the symmetry classes BDI and D leading to protected gapless surface modes. We present a detailed calculation of the resonant Raman/Brillouin scattering vertex relevant to iridate and ruthenate compounds whose low-energy physics is believed to be proximate to these spin-liquid phases. In the symmetry class BDI, we find that while the resonant scattering on thin films can detect the gapless boundary modes of spin liquids, the nonresonant processes do not couple to them. For the symmetry class D, however, we find that the coupling between both types of light-scattering processes and the low-energy surface states is strongly suppressed. Additionally, we describe the effect of weak time-reversal symmetry breaking perturbations on the bulk Raman response of these systems.

  9. Magnetic field power density spectra during 'scatter-free' solar particle events

    Science.gov (United States)

    Tan, L. C.; Mason, G. M.

    1993-01-01

    We have examined interplanetary magnetic field power spectral density during four previously identified 3He-rich flare periods when the about 1 MeV nucleon-1 particles exhibited nearly scatter-free transport from the sun to 1 AU. Since the scattering mean free path A was large, it might be expected that interplanetary turbulence was low, yet the spectral density value was low only for one of the four periods. For the other three, however, the spectral index q of the power density spectrum was near 2.0, a value at which quasi-linear theories predict an increase in the scattering mean free path. Comparing the lambda values from the energetic particles with that computed from a recent quasi-linear theory which includes helicity and the propagation direction of waves, we find lambda(QLT)/lambda(SEP) = 0.08 +/- 0.03 for the four events. Thus, the theory fits the q-dependence of lambda; however, as found for previous quasi-linear theories, the absolute value is low.

  10. Stimulated Brillouin Scattering Enhancement Factor Improvement in a 11.6-GHz-Linewidth 1.5-kW Yb-Doped Fiber Amplifier

    Science.gov (United States)

    Guang-Bo, Liu; Yi-Feng, Yang; Jian-Hua, Wang; Ye, Zheng; Xiao-Long, Chen; Kai, Liu; Chun, Zhao; Yun-Feng, Qi; Bing, He; Jun, Zhou

    2016-07-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos U1330134, 61308024 and 11174305, the National High-Technology Research and Development Program of China under Grant No 2014AA041901, and the Shanghai Natural Science Foundation under Grant No 11ZR1441400.

  11. Rotational spectra and molecular structure

    CERN Document Server

    Wollrab, James E

    1967-01-01

    Physical Chemistry, A Series of Monographs: Rotational Spectra and Molecular Structure covers the energy levels and rotational transitions. This book is divided into nine chapters that evaluate the rigid asymmetric top molecules and the nuclear spin statistics for asymmetric tops. Some of the topics covered in the book are the asymmetric rotor functions; rotational transition intensities; classes of molecules; nuclear spin statistics for linear molecules and symmetric tops; and classical appearance of centrifugal and coriolis forces. Other chapters deal with the energy levels and effects of ce

  12. Influence of laser linewidth on performance of Brillouin optical time domain reflectometry

    Institute of Scientific and Technical Information of China (English)

    Hao Yun-Qi; Ye Qing; Pan Zheng-Qing; Cai Hai-Wen; Qu Rong-Hui

    2013-01-01

    The effects of optical sources with different laser linewidths on Brillouin optical time domain reflectometry (BOTDR) are investigated numerically and experimentally.Simulation results show that the spectral linewidth of spontaneous Brillouin scattering remains almost constant when the laser linewidth is less than 1 MHz at the same pulse width; otherwise,it increases sharply.A comparison between a fiber laser (FL) with 4-kHz linewidth at 3 dB and a distributed feedback (DFB) laser with 3-MHz linewidth is made experimentally.When a constant laser power is launched into the sensing fiber,the fitting linewidths of the beat signals (backscattered Brillouin light and local oscillator (LO)) is about 5 MHz wider for the DFB laser than for the FL and the intensity of the beat signal is about a half.Furthermore,the frequency fluctuation in the long sensing fiber is lower for the FL source,yielding about 2 MHz less than that of the DFB laser,indicating higher temperature/strain resolution.The experimental results are in good agreement with the numerical simulations.

  13. Brillouin optical time-domain analysis sensor with pump pulse amplification.

    Science.gov (United States)

    Mompó, Juan José; Urricelqui, Javier; Loayssa, Alayn

    2016-06-13

    We demonstrate a simple technique to provide conventional Brillouin optical time-domain analysis sensors with mitigation for pump pulse attenuation. The technique is based on operating the sensor in loss configuration so that energy is transferred from the probe wave to the pump pulse that becomes amplified as it counter-propagates with the probe wave. Furthermore, the optical frequency of the probe wave is modulated along the fiber so that the pump pulse experiences a flat total gain spectrum that equally amplifies all the spectral components of the pulse, hence, preventing distortion. This frequency modulation of the probe brings additional advantages because it provides increased tolerance to non-local effects and to spontaneous Brillouin scattering noise, so that a probe power above the Brillouin threshold of the fiber can be safely deployed, hence, increasing the signal-to-noise ratio of the measurement. The method is experimentally demonstrated in a 100-km fiber link, obtaining a measurement uncertainty of 1 MHz at the worst-contrast position. PMID:27410288

  14. Stimulated scattering from laser produced plasma

    International Nuclear Information System (INIS)

    Stimulated Brillouin and Raman scattering are of considerable interest because of their importance to basic nonlinear plasma physics phenomena and to laser-driven inertial confinement fusion. Induced scattering can be substantial for high intensity (I), long wavelength (λ) lasers because the instability growth rates depend exponentially on Iλ2, and also for short wavelength, long scalelength (L) laser/plasma interaction because of nearly homogeneous or large convective gain conditions. Experimental results from both KrF and CO2 laser/plasma interaction studies are presented to illustrate important wavelength dependent features of induced scattering such as the nature of the instability (absolute, convective), threshold, spectra, reflectivity and saturation effects. Backscattering characteristics have been measured for solid target plasma (aluminium, gold) produced by KrF laser pulses focused to intensities 14 W/cm2 and gas targets (hydrogen, oxygen) by CO2 laser pulses at intensities 13 W/cm2. Collisional absorption dominates the KrF laser experiments, whereas particle heating and increased Landau damping dominate the CO2 laser experiments. Current theoretical work concerned with nonlinear effects in Langmuir wave localization, wave collapse and particle heating (generating characteristic high temperature electrons) is also presented. (author)

  15. Polarized Raman spectra and intensities of aliphatic amino acids

    Science.gov (United States)

    Himmler, Hans J.; Eysel, Hans H.

    1989-01-01

    Raman spectra of aliphatic α- L-amino acids, glycine, alanine, and valine were re-investigated both in aqueous solution and deuterium oxide solution. The spectra were taken of the zwitterionic and of the completely deprotonated form of the amino acids. Spectra of leucine and isoleucine were studied in water at the isoelectric point. Spectra were recorded both with parallel and perpendicular polarization and the isotropic and anisotropic scattering components were isolated. The integrated intensities of CH stretch, CC stretch and carboxylate bend vibrations are discussed. Linear relations between the number of CC and CH bonds and the total scattered intensity in the appropriate spectral regions are observed. The sum over the carboxylate modes shows characteristic intensities for the first three members of the aliphatic amino acids. An increase of isotropic scattering of ϱ co 2 near 510 cm -1 with increasing chain length of the amino acid (or with increasing concentration) is interpreted as the result of micelle formation.

  16. Light scattering reviews 8 radiative transfer and light scattering

    CERN Document Server

    Kokhanovsky, Alexander A

    2013-01-01

    Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.

  17. Duality properties between spectra and tilings

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Spectra and tilings play an important role in analysis and geometry respectively.The relations between spectra and tilings have bafied the mathematicians for a long time.Many conjectures,such as the Fuglede conjecture,are placed on the establishment of relations between spectra and tilings,although there are no desired results.In the present paper we derive some characteristic properties of spectra and tilings which highlight certain duality properties between them.

  18. Strongly Enhanced Stimulated Brillouin Backscattering in an Electron-Positron Plasma

    Science.gov (United States)

    Edwards, Matthew R.; Fisch, Nathaniel J.; Mikhailova, Julia M.

    2016-01-01

    Stimulated Brillouin backscattering of light is shown to be drastically enhanced in electron-positron plasmas, in contrast to the suppression of stimulated Raman scattering. A generalized theory of three-wave coupling between electromagnetic and plasma waves in two-species plasmas with arbitrary mass ratios, confirmed with a comprehensive set of particle-in-cell simulations, reveals violations of commonly held assumptions about the behavior of electron-positron plasmas. Specifically, in the electron-positron limit three-wave parametric interaction between light and the plasma acoustic wave can occur, and the acoustic wave phase velocity differs from its usually assumed value.

  19. 最新英文防护文献报道(三)——应用于生物恐怖威胁的布里渊光谱数据法

    Institute of Scientific and Technical Information of China (English)

    ByRubel; G.O.Fung; 李铁虎

    2004-01-01

    Brillouin scattering from biological materials is conducted using a tandem Fabry-Perot interferometer. The interferometer is uniquely designed to measure small frequency shifts that are characteristic of Brillouin scattering. Brillouin scattering from DNA, ovalbumen, the Bacillus spores globigii and thuringiensis were measured to determine the feasibility of biological material discrimination using Brillouin scattering. It was found that all biological materials exhibited unique Brillouin spectra and that it was possible to discern Bacillusspores at the species level.

  20. Parametrized spectra, multiplicative Thom spectra, and the twisted Umkehr map

    CERN Document Server

    Ando, Matthew; Gepner, David

    2011-01-01

    We introduce and study a general theory of objects parametrized by spaces, in the setting of infinity categories. This framework specializes to give an infinity categorical model of parametrized spectra, and we apply these foundations to study the multiplicative properties of the generalized Thom spectrum functor. As part of this work we study the Picard space of a presentable monoidal infinity category. We sharpen classical results due to Lewis about the multiplicative properties of the Thom isomorphism. Our main application is the construction of twisted Umkehr maps on twistings of generalized cohomology theories.

  1. Effects of Fe-deficiency on magnetic properties and Brillouin function characteristics for NiCuZn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Linglong; Yu, Zhong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Yang, Yan [Department of Communication Engineering, Chengdu Technological University, Chengdu 611730 (China); Guo, Rongdi; Jiang, Xiaona; Sun, Ke; Wu, Chuanjian; Lan, Zhongwen [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-08-01

    The polycrystalline Ni{sub 0.56}Cu{sub 0.10}Zn{sub 0.34}Fe{sub 2−x}O{sub 4−3/2x} (x=0.00~0.14) ferrites have been prepared by conventional oxide ceramics process. The effects of Fe-deficiency content on magnetic properties and Brillouin function characteristics for NiCuZn ferrites have been investigated in details. With the increase of Fe-deficiency content, the opposite variation trend are observed for the saturation magntic induction B{sub s} and the coercivity H{sub c}. More importantly, based on the Néel molecular field theory, for the spinel ferrites which do not only contain Fe{sup 3+} but also some other multiple magnetic ions (Ni{sup 2+} and Cu{sup 2+}), the molecular field coefficients ω{sub aa}, ω{sub bb} and ω{sub ab=}ω{sub ba} are calculated by non-linear fitting method, and the Curie temperature T{sub c} formula has been modified. With the increase of Fe-deficiency content, the values of ω{sub aa} and ω{sub bb} increase gradually, however, the value of ω{sub ab}=ω{sub ba} has a contrary trend which results in the decrease of the Curie temperature. In addition, the fitting Curie temperatures values are coincided well with the Curie temperatures calculated by the modified formula. - Highlights: • Néel molecular field theory model of multi-magnetic ions (Fe{sup 3+}, Ni{sup 2+}, Cu{sup 2+}) is completed and the correlation formula of Curie temperature has been derived. • The calculating for the molecular field coefficients has been completed from absolute zero degree to Curie temperature. • The corresponding values and variation trend of molecular field coefficients have been completely investigated.

  2. Raman scattering of few-layers MoTe2

    Science.gov (United States)

    Grzeszczyk, M.; Gołasa, K.; Zinkiewicz, M.; Nogajewski, K.; Molas, M. R.; Potemski, M.; Wysmołek, A.; Babiński, A.

    2016-06-01

    We report on room-temperature Raman scattering measurements in few-layer crystals of exfoliated molybdenum ditelluride (MoTe2) performed with the use of 632.8 nm (1.96 eV) laser light excitation. In agreement with a recent study reported by Froehlicher et al (2015 Nano Lett. 15 6481) we observe a complex structure of the out-of-plane vibrational modes ({{{A}}}1{{g}}{/{{A}}}1\\prime ), which can be explained in terms of interlayer interactions between single atomic planes of MoTe2. In the case of low-energy shear and breathing modes of rigid interlayer vibrations, it is shown that their energy evolution with the number of layers can be well reproduced within a linear chain model with only the nearest neighbor interaction taken into account. Based on this model the corresponding in-plane and out-of-plane force constants are determined. We also show that the Raman scattering in MoTe2 measured using 514.5 nm (2.41 eV) laser light excitation results in much simpler spectra. We argue that the rich structure of the out-of-plane vibrational modes observed in Raman scattering spectra excited with the use of 632.8 nm laser light results from its resonance with the electronic transition at the M point of the MoTe2 first Brillouin zone.

  3. Dense Plasma X-ray Scattering: Methods and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Glenzer, S H; Lee, H J; Davis, P; Doppner, T; Falcone, R W; Fortmann, C; Hammel, B A; Kritcher, A L; Landen, O L; Lee, R W; Munro, D H; Redmer, R; Weber, S

    2009-08-19

    We have developed accurate x-ray scattering techniques to measure the physical properties of dense plasmas. Temperature and density are inferred from inelastic x-ray scattering data whose interpretation is model-independent for low to moderately coupled systems. Specifically, the spectral shape of the non-collective Compton scattering spectrum directly reflects the electron velocity distribution. In partially Fermi degenerate systems that have been investigated experimentally in laser shock-compressed beryllium, the Compton scattering spectrum provides the Fermi energy and hence the electron density. We show that forward scattering spectra that observe collective plasmon oscillations yield densities in agreement with Compton scattering. In addition, electron temperatures inferred from the dispersion of the plasmon feature are consistent with the ion temperature sensitive elastic scattering feature. Hence, theoretical models of the static ion-ion structure factor and consequently the equation of state of dense matter can be directly tested.

  4. Measurement of charged particle spectra in deep-inelastic ep scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Alexa, C.; Dobre, M.; Rotaru, M.; Stoicea, G. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A.; Baghdasaryan, S.; Zohrabyan, H. [Yerevan Physics Institute, Yerevan (Armenia); Bartel, W.; Belov, P.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Grebenyuk, A.; Habib, S.; Haidt, D.; Kleinwort, C.; Kraemer, M.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Radescu, V.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E. [DESY, Hamburg (Germany); Begzsuren, K.; Ravdandorj, T. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Boudry, V.; Specka, A. [Ecole Polytechnique, CNRS/IN2P3, LLR, Palaiseau (France); Bozovic-Jelisavcic, I.; Pandurovic, M. [University of Belgrade, Vinca Institute of Nuclear Sciences, Belgrade (Serbia); Brandt, G. [Oxford University, Department of Physics, Oxford (United Kingdom); Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F. [Universite Paris-Sud, CNRS/IN2P3, LAL, Orsay (France); Buniatyan, A.; Huber, F.; Pirumov, H.; Sauter, M.; Schoening, A. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Bylinkin, A.; Bystritskaya, L.; Fedotov, A.; Lubimov, V.; Rostovtsev, A.; Tseepeldorj, B. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E. [CINVESTAV, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Ceccopieri, F.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Roosen, R.; Staykova, Z.; Mechelen, P.Van [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerpen (Belgium); Cerny, K.; Pokorny, B.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R. [Charles University, Faculty of Mathematics and Physics, Praha (Czech Republic); Chekelian, V.; Grindhammer, G.; Kiesling, C. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Cvach, J.; Hladky and grave, J.; Reimer, P.; Zalesak, J. [Academy of Sciences of the Czech Republic, Institute of Physics, Praha (Czech Republic); Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Daum, K.; Meyer, H. [Universitaet Wuppertal, Fachbereich C, Wuppertal (Germany); Diaconu, C.; Hoffmann, D.; Sauvan, E.; Vallee, C. [Aix-Marseille Univ, CNRS/IN2P3, CPPM, Marseille (France); Dodonov, V. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Dossanov, A. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Max-Planck-Institut fuer Physik, Muenchen (Germany); Egli, S.; Hildebrandt, M.; Horisberger, R. [Paul Scherrer Institut, Villigen (Switzerland); Feltesse, J.; Perez, E.; Schoeffel, L. [CE-Saclay, CEA, DSM/Irfu, Gif-sur-Yvette (France); Ferencei, J. [Slovak Academy of Sciences, Institute of Experimental Physics, Kosice (Slovakia); Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J. [Institute for Nuclear Physics, Cracow (Poland); Grab, C. [ETH, Institut fuer Teilchenphysik, Zuerich (Switzerland); Henderson, R.C.W. [University of Lancaster, Department of Physics, Lancaster (United Kingdom); Hennekemper, E.; Herbst, M.; Schultz-Coulon, H.C. [Universitaet Heidelberg, Kirchhoff-Institut fuer Physik, Heidelberg (Germany); Herrera, G.; Lopez-Fernandez, R. [CINVESTAV IPN, Departamento de Fisica, Mexico City (Mexico); Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T. [DESY, Zeuthen (Germany); Joensson, L. [University of Lund, Physics Department, Lund (Sweden); Jung, H. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerpen (Belgium); DESY, Hamburg (Germany); Kapichine, M.; Morozov, A.; Nikitin, D.; Palichik, V.; Spaskov, V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kogler, R.; Nowak, K. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Landon, M.P.J.; Rizvi, E.; Traynor, D. [Queen Mary, University of London, School of Physics and Astronomy, London (United Kingdom); Martyn, H.U. [I. Physikalisches Institut der RWTH, Aachen (Germany); Morris, J.V.; Sankey, D.P.C. [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire (United Kingdom); Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P. [Physik-Institut der Universitaet Zuerich, Zuerich (Switzerland); Newman, P.R.; Thompson, P.D. [University of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Picuric, I.; Raicevic, N. [University of Montenegro, Faculty of Science, Podgorica (Montenegro); Soloviev, Y. [DESY, Hamburg (Germany); Lebedev Physical Institute, Moscow (Russian Federation); Stella, B. [Dipartimento di Fisica Universita di Roma Tre (Italy); INFN Roma 3, Roma (Italy); Sykora, T. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerpen (Belgium); Charles University, Faculty of Mathematics and Physics, Praha (Czech Republic); Tsakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Wegener, D. [TU Dortmund, Institut fuer Physik, Dortmund (Germany); Collaboration: The H1 Collaboration

    2013-04-15

    Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5 < Q{sup 2} < 100 GeV{sup 2}, and small values of Bjorken-x, 10{sup -4} < x < 10{sup -2}. The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity ({eta}{sup *}) and transverse momentum (p{sub T}{sup *}) in the range 0<{eta}{sup *} < 5 and 0and Q{sup 2}. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions. (orig.)

  5. Measurement of Charged Particle Spectra in Deep-Inelastic ep Scattering at HERA

    CERN Document Server

    Alexa, C; Baghdasaryan, A; Baghdasaryan, S; Bartel, W; Begzsuren, K; Belousov, A; Belov, P; Boudry, V; Bozovic-Jelisavcic, I; Brandt, G; Brinkmann, M; Brisson, V; Britzger, D; Buniatyan, A; Bylinkin, A; Bystritskaya, L; Campbell, A J; Cantun Avila, K B; Ceccopieri, F; Cerny, K; Chekelian, V; Contreras, J G; Cvach, J; Dainton, J B; Daum, K; De Wolf, E A; Diaconu, C; Dobre, M; Dodonov, V; Dossanov, A; Eckerlin, G; Egli, S; Elsen, E; Favart, L; Fedotov, A; Felst, R; Feltesse, J; Ferencei, J; Fischer, D J; Fleischer, M; Fomenko, A; Gabathuler, E; Gayler, J; Ghazaryan, S; Glazov, A; Goerlich, L; Gogitidze, N; Gouzevitch, M; Grab, C; Grebenyuk, A; Greenshaw, T; Grindhammer, G; Habib, S; Haidt, D; Henderson, R C W; Hennekemper, E; Herbst, M; Herrera, G; Hildebrandt, M; Hiller, K H; Hladky, J; Hoffmann, D; Horisberger, R; Hreus, T; Huber, F; Jacquet, M; Janssen, X; Jonsson, L; Jung, H; Kapichine, M; Kiesling, C; Klein, M; Kleinwort, C; Kogler, R; Kostka, P; Kramer, M; Kretzschmar, J; Kruger, K; Landon, M P P J; Lange, W; Laycock, P; Lebedev, A; Levonian, S; Lipka, K; List, B; List, J; Lobodzinski, B; Lopez-Fernandez, R; Lubimov, V; Malinovski, E; Martyn, H H U; Maxfield, S S J; Mehta, A; Meyer, A B; Meyer, H; Meyer, J; Mikocki, S; Milcewicz-Mika, I; Morozov, A; Morris, J V; Muller, K; Naumann, Th; Newman, P R; Niebuhr, C; Nikitin, D; Nowak, G; Nowak, K; Olsson, J E; Ozerov, D; Pahl, P; Palichik, V; Pandurovic, M; Pascaud, C; Patel, G D; Perez, E; Petrukhin, A; Picuric, I; Pirumov, H; Pitzl, D; Placakyte, R; Pokorny, B; Polifka, R; Radescu, V; Raicevic, N; Ravdandorj, T; Reimer, P; Rizvi, E; Robmann, P; Roosen, R; Rostovtsev, A; Rotaru, M; Ruiz Tabasco, J E; Rusakov, S; Salek, D; Sankey, D P C; Sauter, M; Sauvan, E; Schmitt, S; Schoeffel, L; Schoning, A; Schultz-Coulon, H H C; Sefkow, F; Shushkevich, S; Soloviev, Y; Sopicki, P; South, D; Spaskov, V; Specka, A; Staykova, Z; Steder, M; Stella, B; Stoicea, G; Straumann, U; Sykora, T; Thompson, P D; Traynor, D; Truol, P; Tsakov, I; Tseepeldorj, B; Turnau, J; Valkarova, A; Vallee, C; Van Mechelen, P; Vazdik, Y; Wegener, D; Wunsch, E; Zacek, J; Zalesak, J; Zhang, Z; Zlebcik, R; Zohrabyan, H; Zomer, F

    2013-01-01

    Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5 < Q^2 < 100 GeV^2, and small values of Bjorken-x, 10^{-4} < x < 10^{-2}. The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity (eta^*) and transverse momentum (p_T^*) in the range 0< \\eta^* < 5 and 0< p_T^* < 10$ GeV differentially in x and Q^2. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.

  6. Measurement of charged particle spectra in deep-inelastic ep scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A. [Yerevan Physics Institute (Armenia)] [and others; Collaboration: H1 Collaboration

    2013-01-15

    Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5and small values of Bjorken-x, 10{sup -4}and transverse momentum (p{sub T}{sup *}) in the range 0<{eta}{sup *}<5 and 0and Q{sup 2}. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.

  7. Carbon nanohorn-based nanofluids: characterization of the spectral scattering albedo.

    Science.gov (United States)

    Mercatelli, Luca; Sani, Elisa; Giannini, Annalisa; Di Ninni, Paola; Martelli, Fabrizio; Zaccanti, Giovanni

    2012-01-01

    The full characterization of the optical properties of nanofluids consisting of single-wall carbon nanohorns of different morphologies in aqueous suspensions is carried out using a novel spectrophotometric technique. Information on the nanofluid scattering and absorption spectral characteristics is obtained by analyzing the data within the single scattering theory and validating the method by comparison with previous monochromatic measurements performed with a different technique. The high absorption coefficient measured joint to the very low scattering albedo opens promising application perspectives for single-wall carbon nanohorn-based fluid or solid suspensions. The proposed approximate approach can be extended also to other low-scattering turbid media.PACS: 78.35.+c Brillouin and Rayleigh scattering, other light scattering; 78.40.Ri absorption and reflection spectra, fullerenes and related materials; 81.05.U- carbon/carbon-based materials; 78.67.Bf optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures, nanocrystals, nanoparticles, and nanoclusters. PMID:22297089

  8. Electromagnetic Scattering and Material Characterization

    CERN Document Server

    Omar, Abbas

    2011-01-01

    Based on the author's more-than 30 years of experience, this first-of-its-kind volume presents a comprehensive and systematic analysis of electromagnetic fields and their scattering by material objects. The book considers all three categories of scattering environments commonly used for material measurements – unbounded regions, waveguides, and cavity resonators. The book covers such essential topics as electromagnetic field propagation, radiation, and scattering, containing mathematically rigorous approaches for the computation of electromagnetic fields and the explanation of their behavior.

  9. Optical Scattering Measurement and Analysis

    CERN Document Server

    Stover, John C

    2009-01-01

    As the authoritative resource on optical scattering, this book was developed from many years of teaching light-scatter measurement and analysis courses to optical engineers. Dr. Stover covers scattering beginning with its basics and covering surface roughness calculations, measurements, instrumentation, predictions, specifications, and industrial applications. Also included are appendices that review the basics of wave propagation and Kirchhoff diffraction. Whether you're an optical engineer currently investigating roughness-induced haze in the semiconductor industry, or just entering the fiel

  10. Retrieval of stratospheric aerosol size information from OSIRIS limb scattered sunlight spectra

    Directory of Open Access Journals (Sweden)

    A. E. Bourassa

    2008-02-01

    Full Text Available Recent work has shown that the retrieval of stratospheric aerosol vertical profiles is possible using limb scattered sunlight measurements at optical wavelengths. The aerosol number density profile is retrieved for an assumed particle size distribution and composition. This result can be used to derive the extinction at the measured wavelength. However, large systematic error can result from the uncertainty in the assumed size distribution when the result is used to estimate the extinction at other wavelengths. It is shown in this work that the addition of information obtained from the near infrared limb radiance profile at 1530 nm measured by the imaging module of the OSIRIS instrument yields an indication of the aerosol size distribution profile that can be used to improve the fidelity of the retrievals. A comparison of the estimated extinction profile at 1020 nm with coincident occultation measurements demonstrates agreement to within approximately 15% from 12 to 27 km altitude.

  11. Born approximation, scattering, and algorithm

    Science.gov (United States)

    Martinez, Alex; Hu, Mengqi; Gu, Haicheng; Qiao, Zhijun

    2015-05-01

    In the past few decades, there were many imaging algorithms designed in the case of the absence of multiple scattering. Recently, we discussed an algorithm for removing high order scattering components from collected data. This paper is a continuation of our previous work. First, we investigate the current state of multiple scattering in SAR. Then, we revise our method and test it. Given an estimate of our target reflectivity, we compute the multi scattering effects in the target region for various frequencies. Furthermore, we propagate this energy through free space towards our antenna, and remove it from the collected data.

  12. Irreducible Brillouin conditions and contracted Schroedinger equations for n-electron systems. III. Systems of noninteracting electrons

    International Nuclear Information System (INIS)

    We analyze the structure and the solutions of the irreducible k-particle Brillouin conditions (IBCk) and the irreducible contracted Schroedinger equations (ICSEk) for an n-electron system without electron interaction. This exercise is very instructive in that it gives one both the perspective and the strategies to be followed in applying the IBC and ICSE to physically realistic systems with electron interaction. The IBC1 leads to a Liouville equation for the one-particle density matrix γ1=γ, consistent with our earlier analysis that the IBC1 holds both for a pure and an ensemble state. The IBC1 or the ICSE1 must be solved subject to the constraints imposed by the n-representability condition, which is particularly simple for γ. For a closed-shell state γ is idempotent, i.e., all natural spin orbitals (NSO's) have occupation numbers 0 or 1, and all cumulants λk with k≥2 vanish. For open-shell states there are NSO's with fractional occupation number, and at the same time nonvanishing elements of λ2, which are related to spin and symmetry coupling. It is often useful to describe an open-shell state by a totally symmetric ensemble state. If one wants to treat a one-particle perturbation by means of perturbation theory, this mainly as a run-up for the study of a two-particle perturbation, one is faced with the problem that the perturbation expansion of the Liouville equation gives information only on the nondiagonal elements (in a basis of the unperturbed states) of γ. There are essentially three possibilities to construct the diagonal elements of γ: (i) to consider the perturbation expansion of the characteristic polynomial of γ, especially the idempotency for closed-shell states ,(ii) to rely on the ICSE1, which (at variance with the IBC1) also gives information on the diagonal elements, though not in a very efficient manner, and (iii) to formulate the perturbation theory in terms of a unitary transformation in Fock space. The latter is particularly

  13. Influence of multi-orbital hopping and anisotropy in intra and inter orbital Coulomb interactions on the electronic spectra in iron pnictide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Luxmi, E-mail: Luxmiphyiitr@gmail.com; Ajay, E-mail: ajphyfpt@iitr.ernet.in

    2015-03-15

    Highlights: • Analysis of spectral function within BCS mean- field approximation. • The various orbital hopping parameters, onsite Coulomb interactions and Hund’s orbital coupling control the electronic states at different k-point of Brillouin zone in superconducting state. • Hund’s coupling energy and Coulomb correlations show opposite influence on spectral weight as also viewed in terms of ARPES measurement. - Abstract: The present work deals with a theoretical study of the electronic spectral function in iron pnictide superconductors, like LaFeAs(O, F) material. We have attempted three orbital per site model Hamiltonian containing various orbitals hopping energies, onsite intra and inter orbital electronic correlations, and Hund’s coupling energy in Fe 3d orbitals. The expression of single particle spectral function within mean-field Green’s function approach for superconducting state of iron pnictides, is obtained. The single particle spectral function is numerically analyzed for extended s-wave pairing symmetry as a function of various model parameters applicable for these systems. It is pointed out that the nature of electronic states at different k-point of Brillouin zone is essentially influenced by various orbital hopping parameters, onsite Coulomb interaction and Hund’s orbital coupling. At X(0, π) point of Brillouin zone a well-defined three peak spectra is predicted while at Γ(0, 0) and M(π, π) point the electronic spectra show two peaks due to crossing of electronic state (at Γ-point). Our analysis also indicates that Hund’s coupling pile up the spectral weight close to Fermi level and onsite Coulomb correlations suppress the electronic states close to Fermi level at Γ(0, 0) point and show opposite influence on spectral weight at different location of Brillouin zone. Finally, the theoretically obtained behavior of single particle spectral function has been viewed in terms of recent photoemission ARPES measurements and existing

  14. A novel-configuration multi-wavelength Brillouin erbium fiber laser and its application in switchable high-frequency microwave generation

    Science.gov (United States)

    Fu, J.; Chen, D.; Sun, B.; Gao, S.

    2010-10-01

    A novel configuration of compound-cavity multi-wavelength Brillouin erbium fiber laser is proposed and experimentally demonstrated. With an incident optical carrier power of 8 dBm, at least 14 lasing lines are obtained with a wavelength spacing of ˜0.08 nm. Stability and power uniformity of the multi-wave-length lasing are ensured by the flat hybrid gain of Brillouin and erbium, the compound-cavity structure, and the four-wave mixing suppression using a long (10 km) single-mode fiber. A stable and frequency-switchable microwave can be achieved by incorporating a fiber Bragg grating filter to select the desired nth-order Stokes wave and beating it with the optical carrier at a photodetector. In our experiment, the 1st-4th-order Stokes waves are filtered respectively and hence a high-quality microwave with a switchable frequency from ˜10 to ˜40 GHz and a tuning step of ˜10 GHz is achieved. The signal-to-noise ratio is measured to be >25 dB.

  15. Temperature-dependent strain and temperature sensitivities of fused silica single mode fiber sensors with pulse pre-pump Brillouin optical time domain analysis

    Science.gov (United States)

    Bao, Yi; Chen, Genda

    2016-06-01

    This paper reports a distributed temperature and strain sensor based on pulse pre-pump Brillouin optical time domain analysis. An uncoated, telecom-grade fused silica single-mode fiber as a distributed sensor was calibrated for its sensitivity coefficients under various strains and temperatures up to 800 °C. The Brillouin frequency of fiber samples changed nonlinearly with temperature and linearly with strain. The temperature sensitivity decreased from 1.113 to 0.830 MHz /°C in the range of 22–800 °C. The strain sensitivity was reduced from 0.054 to 0.042 MHz /με as the temperature increased from 22 to 700 °C and became unstable at higher temperatures due to creep effect. The strain measurement range was reduced from 19 100 to 6000 με in the temperature range of 22–800 °C due to fused silica’s degradation. The calibrated fiber optic sensor demonstrated adequate accuracy and precision for strain and temperature measurements and stable performance in heating–cooling cycles. It was validated in an application setting.

  16. Squeezed States and Helmholtz Spectra

    CERN Document Server

    Francisco Delgado, C; Reyes, M A; Mielnik, Bogdan; Reyes, Marco A

    1997-01-01

    The 'classical interpretation' of the wave function psi(x) reveals an interesting operational aspect of the Helmholtz spectra. It is shown that the traditional Sturm-Liouville problem contains the simplest key to predict the squeezing effect for charged particle states.

  17. An ultra-wideband tunable multi-wavelength Brillouin fibre laser based on a semiconductor optical amplifier and dispersion compensating fibre in a linear cavity configuration

    International Nuclear Information System (INIS)

    A multi-wavelength Brillouin fibre laser (MBFL) with an ultra-wideband tuning range from 1420 nm to 1620 nm is demonstrated. The MBFL uses an ultra-wideband semiconductor optical amplifier (SOA) and a dispersion compensating fibre (DCF) as the linear gain medium and nonlinear gain medium, respectively. The proposed MBFL has a wide tuning range covering the short (S-), conventional (C-) and long (L-) bands with a wavelength spacing of 0.08 nm, making it highly suitable for DWDM system applications. The output power of the observed Brillouin Stokes ranges approximately from -5.94 dBm to -0.41 dBm for the S-band, from -4.34 dBm to 0.02 dBm for the C-band and from -2.19 dBm to 0.39 dBm for the L-band. The spacing between each adjacent wavelengths of all the three bands is about 0.08 nm, which is approximately 10.7 GHz for the frequency domain. (lasers)

  18. Neutron and photon spectra in LINACs

    International Nuclear Information System (INIS)

    A Monte Carlo calculation, using the MCNPX code, was carried out in order to estimate the photon and neutron spectra in two locations of two linacs operating at 15 and 18 MV. Detailed models of both linac heads were used in the calculations. Spectra were estimated below the flattening filter and at the isocenter. Neutron spectra show two components due to evaporation and knock-on neutrons. Lethargy spectra under the filter were compared to the spectra calculated from the function quoted by Tosi et al. that describes reasonably well neutron spectra beyond 1 MeV, though tends to underestimate the energy region between 10–6 and 1 MeV. Neutron and the Bremsstrahlung spectra show the same features regardless of the linac voltage. - Highlights: ► With MCNPX code realistic models of two LINACs were built. ► Photon and neutron spectra below the flattening filter and at the isocenter were calculated. ► Neutron spectrum at the flattening filter was compared against the Tosi et al. source-term model. ► Tosi et al. model underestimates the neutron contribution below 1 MeV. ► Photon spectra look alike to those published in literature.

  19. Method for fast computation of angular light scattering spectra from 2D periodic arrays

    CERN Document Server

    Pomplun, J; Zschiedrich, L; Gutsche, P; Schmidt, F

    2016-01-01

    An efficient numerical method for computing angle-resolved light scattering off periodic arrays is presented. The method combines finite-element discretization with a Schur complement solver. A significant speed-up of the computations in comparison to standard finite-element method computations is observed.

  20. Plasma characterization using ultraviolet Thomson scattering from ion-acoustic and electron plasma waves (invited)

    Science.gov (United States)

    Follett, R. K.; Delettrez, J. A.; Edgell, D. H.; Henchen, R. J.; Katz, J.; Myatt, J. F.; Froula, D. H.

    2016-11-01

    Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 1021 cm-3, which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation. Practical techniques for including these effects when fitting Thomson-scattering spectra are presented and applied to the measured spectra to show the improvements in plasma characterization.

  1. Determination of Matrine and Oxymatrine in Radix Sophorae Flavescentis by Resonance Rayleigh Scattering, Second-order Scattering and Frequency Doubling Scattering Technique

    Institute of Scientific and Technical Information of China (English)

    SONG Yan-qi; LIU Shao-pu; LIU Zhong-fang; HU Xiao-li

    2011-01-01

    In 0.1 mol/L HCl medium,12-tungstophosphoric(TP) acid reacted with matrine(Mat) and oxymatrine(Oxy)to form an ion-association complex.As a result,the new spectra of resonance Rayleigh scattering(RRS),second-order scattering(SOS) and frequency doubling scattering(FDS) appeared and their intensities were enhanced greatly.The maximum scattering wavelengths of RRS,SOS and FDS were located at 370,670 and 390 nm,respectively.The increments of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range.Based on this,the method for the determination of matrine and oxymatrine has been established.It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result.The reaction mechanism and reasons of RRS enhancement were discussed.

  2. Photonic-phononic orbital angular momentum in Brillouin parametric conversion

    CERN Document Server

    Zhu, Zhihan; Mu, Chunyuan; Li, Hongwei

    2014-01-01

    Orbital angular momentum (OAM) is a fundamental photonic degree of freedom, showed by Allen and co-workers. Its most attractive feature is an inherently infinite dimensionality, which in recent years has obtained several ground-breaking demonstrations for high information-density communication and processing, both in classical and quantum. Here, by seeking the reason for photonic OAM non-conservation in stimulated Brillouin amplification, we report the first demonstration of the evolution law for OAM in Brillouin process. The parameter of OAM can conveniently transfer between the phonons and different polarized photons due to the photonic spin angular momentum conservation. Our results have revealed a parametric conversion mechanism of Brillouin process for Photonic-phononic OAM, demonstrated the role of phononic OAM and the vortex acoustic wave in this process, and suggested this mechanism may find important applications in OAM-based information communication and processing.

  3. General Notes on Processes and Their Spectra

    Directory of Open Access Journals (Sweden)

    Gustav Cepciansky

    2012-01-01

    Full Text Available The frequency spectrum performs one of the main characteristics of a process. The aim of the paper is to show the coherence between the process and its own spectrum and how the behaviour and properties of a process itself can be deduced from its spectrum. Processes are categorized and general principles of their spectra calculation and recognition are given. The main stress is put on power spectra of electric and optic signals, as they also perform a kind of processes. These spectra can be directly measured, observed and examined by means of spectral analyzers and they are very important characteristics which can not be omitted at transmission techniques in telecommunication technologies. Further, the paper also deals with non electric processes, mainly with processes and spectra at mass servicing and how these spectra can be utilised in praxis.

  4. Neutron scattering and hydrogen storage

    Directory of Open Access Journals (Sweden)

    A.J. Ramirez-Cuesta

    2009-11-01

    Full Text Available Hydrogen has been identified as a fuel of choice for providing clean energy for transport and other applications across the world and the development of materials to store hydrogen efficiently and safely is crucial to this endeavour. Hydrogen has the largest scattering interaction with neutrons of all the elements in the periodic table making neutron scattering ideal for studying hydrogen storage materials. Simultaneous characterisation of the structure and dynamics of these materials during hydrogen uptake is straightforward using neutron scattering techniques. These studies will help us to understand the fundamental properties of hydrogen storage in realistic conditions and hence design new hydrogen storage materials.

  5. Temperature sensing based on a Brillouin fiber microwave generator

    Science.gov (United States)

    Yang, X. P.; Gan, J. L.; Xu, S. H.; Yang, Z. M.

    2013-04-01

    We propose and demonstrate a novel dual-frequency Brillouin fiber laser used for microwave generation. Based on this configuration, temperature sensing has been realized. The dual-frequency Brillouin lasing is generated independently from two pieces of fiber cascaded within one ring resonator. Microwave generation is acquired as the beat signal of the dual-frequency Brillouin fiber laser, with the beat frequency being linearly proportional to the temperature difference of the two fiber sections. In the experiment, the temperature coefficient of frequency shift is 1.015 ± 0.001 MHz °C-1. The temperature can be precisely measured by acquiring the frequency of the microwave generator, and this new configuration provides a promising application for temperature sensing.

  6. Brillouin distributed temperature sensing system for monitoring of submarine export cables of off-shore wind farms

    Science.gov (United States)

    Marx, Benjamin; Rath, Alexander; Kolm, Frederick; Schröder, Andreas; Buntebarth, Christian; Dreß, Albrecht; Hill, Wieland

    2016-05-01

    For high-voltage cables, the maximum temperature of the insulation must never be exceeded at any location and at any load condition. The local temperatures depend not only on the cable design and load history, but also on the local thermal environment of the cable. Therefore, distributed temperature monitoring of high-voltage cables is essential to ensure the integrity of the cable at high load. Especially, the load of the export cables of wind farms varies strongly in dependence on weather conditions. In this field study, we demonstrate the measurement performance of a new, robust Brillouin distributed temperature sensing system (Brillouin-DTS). The system is based on spontaneous Brillouin scattering and does not require a fibre loop. This is essential for long submarine high-voltage cables, where normally no loop can be formed in the seabed. It is completely passively cooled and does not contain any moving or wearing parts. The instrument is dedicated for use in industrial and other rough environments. With a measuring time below 10 min, the temperature resolution is better than 1 °C for distances up to 50 km. In the field study, the submarine export cable of an off-shore wind farm has been monitored. The temperature profile of the export cable shows several hot spots, mostly located at cable joints, and also several cold spots.

  7. Absorption and Recurrence Spectra of Sodium Rydberg Atom in a Strong External Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WANG De-Hua; LIN Sheng-Lu

    2004-01-01

    Using core-scattered closed-orbit theory, we calculate the photoabsorption and the scaled recurrence spectra of sodium Rydberg atom in strong magnetic field below ionization threshold. The non-Coulombic nature of the ionic core have been modified by a model potential, which includes an attractive Coulomb potential and a short-ranged core potential. A family of core-scattered nonhydrogenic closed orbits have also been discovered. The Fourier transformed spectra of sodium atom have allowed direct comparison between peaks in such plot and the scaled action values of closed orbits. The new peaks in the recurrence spectra of sodium atom have been considered as effects caused by the core scattering of returning waves at the ionic core. The results are compared with those of hydrogen case, which show that the core-scattered effects play an important role in alkali-metal atoms.

  8. Absorption and Recurrence Spectra of Sodium Rydberg Atom in a Strong External Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WANGDe-Hua; LINSheng-Lu

    2004-01-01

    Using core-scattered closed-orbit theory, we calculate the photoabsorption and the scaled recurrence spectra of sodium Rydberg atom in strong magnetic fied below ionization threshoM. The non-Coulombic nature of the ionic core have been modified by a model potential, which includes an attractive Coulomb potential and a short-ranged core potential. A family of core-scattered nonhydrogenic closed orbits have also been discovered. The Fourier transformed spectra of sodium atom have allowed direct comparison between peaks in such plot and the scaled action values of closed orbits. The new peaks in the recurrence spectra of sodium atom have been considered as effects caused by the core scattering of returning waves at the ionic core. The results are compared with those of hydrogen case, which show that the core-scattered effects play an important role in alkali-metal atoms.

  9. Brillouin spectroscopy of clotting dynamics in a model system

    Science.gov (United States)

    Bustamante-Lopez, Sandra C.; Traverso, Andrew J.; Yakovlev, Vladislav V.; Meissner, Kenith E.

    2016-02-01

    Keys to successful treatment of disease include early diagnosis and timely treatment. It is hypothesized that early clotting events may contribute to a pro-thrombotic state that exacerbates atherothrombotic vascular disease. Brillouin spectroscopy involves inelastic coupling of light with phonons and enables viscoelastic characterization of samples at the microscale. In this work, we apply Brillouin spectroscopy to a model fibrinogen-thrombin clotting system with the goal of measuring clotting dynamics at the microscale and providing characterization that is not possible with standard rheometric techniques. Here, the clotting dynamics of the model clotting system are measured at various fibrinogen and thrombin concentrations.

  10. Neutron scattering and models: Titanium

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.

    1997-07-01

    Differential neutron elastic-scattering cross sections of elemental titanium were measured from 4.5 {r_arrow} 10.0 MeV in incident energy increments of {approx} 0.5 MeV. At each energy the measurements were made at forty or more scattering angles distributed between {approx} 17 and 160{degree}. Concurrently, differential neutron inelastic-scattering cross sections were measured for observed excitations of 0.975 {+-} 0.034, 1.497 {+-} 0.033, 2.322 {+-} 0.058, 3.252 {+-} 0.043, 3.700 {+-} 0.093, 4.317 {+-} 0.075 and 4.795 {+-} 0.100 MeV. All of the observed inelastically-scattered neutron groups were composites of contributions from several isotopes and/or levels. The experimental results were used to develop energy-average optical, statistical and coupled-channels models.

  11. Small-angle scattering theory revisited: Photocurrent and spatial localization

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Michelsen, Poul

    2005-01-01

    In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto......- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize....... Saffman et al., "CO2 laser based two-volume collective scattering instrument for spatially localized turbulence measurements,"Rev. Sci. Instrum. 72, 2579-2592 (2001)]....

  12. Photonic methods of millimeter-wave generation based on Brillouin fiber laser

    Science.gov (United States)

    Al-Dabbagh, R. K.; Al-Raweshidy, H. S.

    2016-05-01

    In optical communication link, generation and delivering millimeter-wave (mm-waves) in radio over fiber (RoF) systems has limitation due to fiber non-linearity effects. To solve this problem, photonic methods of mm-wave generation based on characterizations of Brillouin fiber laser are proposed in this work for the first time. Three novel photonic approaches for mm-wave generation methods based on Brillouin fiber laser and phase modulator are proposed and demonstrated by simulation. According to our theoretical analysis and simulation, mm-waves with frequency up to 80 GHz and good signal to noise ratio (SNR) up to 90 dB are generated by new and cost effective methods of generation that make them suitable for applications of the fifth generation (5G) networks. The proposed configurations increase the stability and the quality of the mm-wave generation system by using a single laser source as a pump wave and the fiber non-linearity effects are reduced. A key advantage of this research is that proposed a number of very simple generation methods and cost effective which only use standard components of optical telecommunications. Stimulated Brillouin Scattering (SBS) effect that exists in the optical fiber is studied with the characterization of phase modulator. An all optically stable mm-wave carriers are achieved successfully in the three different methods with different frequencies from 20 GHz up to 80 GHz. Simulation results show that all these carriers have low phase noise, good SNR ranging between 60 and 90 dB and tuning capability in comparison with previous methods reported. This makes them suitable for mm-wave transmission in RoF systems to transmit data in the next generation networks.

  13. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    Science.gov (United States)

    Dey, S.; Banik, M.; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2016-01-01

    Surface-enhanced Raman scattering (SERS) from bipyridyl ethylene adsorbed on gold dumbbells shows Fano-like spectra at high incident light intensity. This is accompanied by an increased electronic temperature, while no vibrational anti-Stokes scattering is observed. Theory indicates that interference between vibrational and electronic Raman scattering can yield such asymmetric scattering lineshapes. The best fit to observations is however obtained by disregarding this coupling and accounting for the detailed lineshape of the continuous electronic component of the SERS.

  14. Mass Spectra of Tetraselenafulvalenes, Diselenadithiafulvalenes and Tetrathiafulvalenes

    DEFF Research Database (Denmark)

    Andersen, Jan Rud; Egsgaard, Helge; Larsen, Elfinn;

    1978-01-01

    The mass spectra of 13 heterofulvalenes are reported. The spectra show great similarities within the selenium and within the sulphur series. The main difference between the selenium and the sulphur compounds results from the more facile loss of selenium compared with sulphur, and from the first...... fragmentation of the molecular ion, as the selenium fulvalenes lose an alkyne molecule, whereas the sulphur fulvalenes first lose an (SĊR) radical. An important feature of the spectra of the simple heterofulvalenes is the formation of a rearrangement ion by migration of a heteroatom. The mechanism was...

  15. Raman Scattering by Molecular Hydrogen and Nitrogen in Exoplanetary Atmospheres

    CERN Document Server

    Oklopčić, Antonija; Heng, Kevin

    2016-01-01

    An important source of opacity in the atmospheres of exoplanets at short visible and near-UV wavelengths is Rayleigh scattering of light on molecules. It is accompanied by a related, albeit weaker process -- Raman scattering. In this paper, we analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets, which could provide valuable information about planetary atmospheres. Raman scattering affects the geometric albedo spectra of planets in two main ways. Firstly, it causes filling-in of strong absorption lines in the incident radiation, thus producing sharp peaks in the albedo. Secondly, it shifts the wavelengths of spectral features in the reflected light causing the so-called Raman ghost lines. Observing the Raman peaks in the albedo could be used to measure the column density of the scattering molecule, thus providing constrains on the presence of clouds and hazes in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically iden...

  16. Cyclotron resonant scattering feature simulations. I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling

    CERN Document Server

    Schwarm, F -W; Falkner, S; Pottschmidt, K; Wolff, M T; Becker, P A; Sokolova-Lapa, E; Klochkov, D; Ferrigno, C; Fuerst, F; Hemphill, P B; Marcu-Cheatham, D M; Dauser, T; Wilms, J

    2016-01-01

    Electron cyclotron resonant scattering features (CRSFs) are observed as absorption-like lines in the spectra of X-ray pulsars. A significant fraction of the computing time for Monte Carlo simulations of these quantum mechanical features is spent on the calculation of the mean free path for each individual photon before scattering, since it involves a complex numerical integration over the scattering cross section and the (thermal) velocity distribution of the scattering electrons. We aim to numerically calculate interpolation tables which can be used in CRSF simulations to sample the mean free path of the scattering photon and the momentum of the scattering electron. The tables also contain all the information required for sampling the scattering electron's final spin. The tables were calculated using an adaptive Simpson integration scheme. The energy and angle grids were refined until a prescribed accuracy is reached. The tables are used by our simulation code to produce artificial CRSF spectra. The electron...

  17. Calculation of Vibrational Energy-Spectra of α-Helical Protein Molecules and Its Properties

    Institute of Scientific and Technical Information of China (English)

    PANG XiaoFeng; CHEN XiangRong

    2002-01-01

    The quantum vibrational energy-spectra of amide-Is in alpha-protein molecules are calculated by using the discretely nonlinear Schrodinger equation and physical parameters appropriate to the systems on the basis of theory of bio-energy transport. The numerical results for the energy-spectra are basically consistent with the experimental values obtained by the infrared absorption and Raman scattering and emission-spectra of infrared lights of person's hand-fingers. Utilizing the energy-spectra we explain the laser-Raman spectrum from metabolically active E. Coli. and give some features of the infrared absorption of the protein molecules.

  18. N=2 supersymmetric quantum mechanics and the inverse scattering problem

    International Nuclear Information System (INIS)

    Connection between the N=2 supersymmetrical quantum mechanics and the inverse scattering problem is established. In contrast to the N=1 supersymmetrical quantum mechanics, in the approach under consideration, the rearrangement of spectra is possible in the construction of isospectral Hamiltonians which concern both ground and excited states

  19. Integrated Raman and angular scattering of single biological cells

    Science.gov (United States)

    Smith, Zachary J.

    2009-12-01

    Raman, or inelastic, scattering and angle-resolved elastic scattering are two optical processes that have found wide use in the study of biological systems. Raman scattering quantitatively reports on the chemical composition of a sample by probing molecular vibrations, while elastic scattering reports on the morphology of a sample by detecting structure-induced coherent interference between incident and scattered light. We present the construction of a multimodal microscope platform capable of gathering both elastically and inelastically scattered light from a 38 mum2 region in both epi- and trans-illumination geometries. Simultaneous monitoring of elastic and inelastic scattering from a microscopic region allows noninvasive characterization of a living sample without the need for exogenous dyes or labels. A sample is illuminated either from above or below with a focused 785 nm TEM00 mode laser beam, with elastic and inelastic scattering collected by two separate measurement arms. The measurements may be made either simultaneously, if identical illumination geometries are used, or sequentially, if the two modalities utilize opposing illumination paths. In the inelastic arm, Stokes-shifted light is dispersed by a spectrograph onto a CCD array. In the elastic scattering collection arm, a relay system images the microscope's back aperture onto a CCD detector array to yield an angle-resolved elastic scattering pattern. Post-processing of the inelastic scattering to remove fluorescence signals yields high quality Raman spectra that report on the sample's chemical makeup. Comparison of the elastically scattered pupil images to generalized Lorenz-Mie theory yields estimated size distributions of scatterers within the sample. In this thesis we will present validations of the IRAM instrument through measurements performed on single beads of a few microns in size, as well as on ensembles of sub-micron particles of known size distributions. The benefits and drawbacks of the

  20. Selection and Characterization of Interesting Grism Spectra

    CERN Document Server

    Meurer, G R

    2006-01-01

    Observations with the ACS Wide Field Camera and G800L grism can produce thousands of spectra within a single WFC field producing a potentially rich treasure trove of information. However, the data are complicated to deal with. Here we describe algorithms to find and characterize spectra of emission line galaxies and supernovae using tools we have developed in conjunction with off the shelf software.

  1. Scintillation Dynamic Spectra and Transverse Velocities of Seven Pulsars

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using a pulsar timing system developed at Urumqi Astronomical Observatory's 25-m telescope, we observed scintillation dynamic spectra for seven pulsars at the relatively high frequency of 1540 MHz over a wide frequency band of 320 MHz. Averaging observations at different epochs, we obtain time scales and decorrelation bandwidths for diffractive scintillation and show that these imply a power-law index for the electron density fluctuation close to 4.0. Assuming this value and that the scattering disk is approximately midway between the pulsar and the earth, we compute transverse velocities for the seven pulsars. These values are generally in good agreement with the proper motion velocities.

  2. Microresonator Brillouin Laser Stabilization Using a Microfabricated Rubidium Cell

    CERN Document Server

    Loh, William; Leopardi, Holly F; Fortier, Tara M; Quinlan, Frank; Kitching, John; Papp, Scott B; Diddams, Scott A

    2016-01-01

    We frequency stabilize the output of a miniature stimulated Brillouin scattering (SBS) laser to rubidium atoms in a microfabricated cell to realize a laser system with frequency stability at the $10^{-11}$ level over seven decades in averaging time. In addition, our system has the advantages of robustness, low cost and the potential for integration that would lead to still further miniaturization. The SBS laser operating at 1560 nm exhibits a spectral linewidth of 820 Hz, but its frequency drifts over a few MHz on the 1 hour timescale. By locking the second harmonic of the SBS laser to the Rb reference, we reduce this drift by a factor of $10^3$ to the level of a few kHz over the course of an hour. For our combined SBS and Rb laser system, we measure a frequency noise of $4\\times10^4$ $Hz^2/Hz$ at 10 Hz offset frequency which rapidly rolls off to a level of 0.2 $Hz^2/Hz$ at 100 kHz offset. The corresponding Allan deviation is $\\leq2\\times10^{-11}$ for averaging times spanning $10^{-4}$ to $10^3$ s. By optical...

  3. Beyond the Brillouin limit with the Penning fusion experiment

    International Nuclear Information System (INIS)

    Several years ago, it was proposed that a dense nonneutral plasma could be produced in a Penning trap. Nonneutral plasmas have excellent confinement. Thus, such a dense plasma might produce simultaneously high density and good confinement (as needed for fusion). Recently, this theoretical conjecture has been demonstrated in a small (3 mm radius) electron experiment (PFX). Densities up to 35 times the Brillouin density (limiting number density in a static trap) have been inferred from the observed strong (100:1) spherical focussing. Electrons are injected at low energy from a single pole of the sphere. A surprising observation is the self-organization of the system into a spherical state, which occurs precisely when the trap parameters are adjusted to produce a spherical well. This organization is observed by a bootstrapping which produces a hysteresis. Additional observations which confirm the dense spherical focus are energy-scattered electrons and deflections of an electron probe beam by the space charge of the central focus

  4. Direct time integration of Maxwell's equations in linear dispersive media with absorption for scattering and propagation of femtosecond electromagnetic pulses

    Science.gov (United States)

    Joseph, Rose M.; Hagness, Susan C.; Taflove, Allen

    1991-01-01

    The initial results for femtosecond pulse propagation and scattering interactions for a Lorentz medium obtained by a direct time integration of Maxwell's equations are reported. The computational approach provides reflection coefficients accurate to better than 6 parts in 10,000 over the frequency range of dc to 3 x 10 to the 16th Hz for a single 0.2-fs Gaussian pulse incident upon a Lorentz-medium half-space. New results for Sommerfeld and Brillouin precursors are shown and compared with previous analyses. The present approach is robust and permits 2D and 3D electromagnetic pulse propagation directly from the full-vector Maxwell's equations.

  5. Relativistic Brillouin flow in the high ν/γ diode

    International Nuclear Information System (INIS)

    Relativistic Brillouin solutions have been derived for electron flow in crossed electric and magnetic fields. The application of these solutions to the high ν/γ diode is discussed and an approximate analytical expression for the anode current is derived. Measurements of diode current are compared to the theoretical and empirical expressions for diode current which have been developed

  6. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS

    Science.gov (United States)

    MacDonald, M. J.; Gorkhover, T.; Bachmann, B.; Bucher, M.; Carron, S.; Coffee, R. N.; Drake, R. P.; Ferguson, K. R.; Fletcher, L. B.; Gamboa, E. J.; Glenzer, S. H.; Göde, S.; Hau-Riege, S. P.; Kraus, D.; Krzywinski, J.; Levitan, A. L.; Meiwes-Broer, K.-H.; O'Grady, C. P.; Osipov, T.; Pardini, T.; Peltz, C.; Skruszewicz, S.; Swiggers, M.; Bostedt, C.; Fennel, T.; Döppner, T.

    2016-11-01

    Atomic clusters can serve as ideal model systems for exploring ultrafast (˜100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination with a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.

  7. High frequency and pulse scattering physical acoustics

    CERN Document Server

    Pierce, Allan D

    1992-01-01

    High Frequency and Pulse Scattering investigates high frequency and pulse scattering, with emphasis on the phenomenon of echoes from objects. Geometrical and catastrophe optics methods in scattering are discussed, along with the scattering of sound pulses and the ringing of target resonances. Caustics and associated diffraction catastrophes are also examined.Comprised of two chapters, this volume begins with a detailed account of geometrically based approximation methods in scattering theory, focusing on waves transmitted through fluid and elastic scatterers and glory scattering; surface ray r

  8. Neutron Thermalization and Reactor Spectra. Vol. I. Proceedings of the Symposium on Neutron Thermalization and Reactor Spectra

    International Nuclear Information System (INIS)

    Proceedings of a Symposium organized by the IAEA and held at Ann Arbor, Michigan, USA, 17 - 21 July 1967. The meeting was attended by 143 participants from 24 Member States and one international organization. Contents: (Vol.I) Theory of neutron thermalization (15 papers); Scattering law (20 papers); Angular, space, temperature and time dependence of neutron spectra (9 papers). (Vol.II) Measurement of thermal neutron spectra and spectral indices, and comparison with theory (17 papers); Time-dependent problems in neutron thermalization (12 papers). Each paper is in its original language (61 English, 1 French and 11 Russian) and is preceded by an abstract in English with one in the original language if this is not English. Discussions are in English. (author)

  9. Neutron Thermalization and Reactor Spectra. Vol. II. Proceedings of the Symposium on Neutron Thermalization and Reactor Spectra

    International Nuclear Information System (INIS)

    Proceedings of a Symposium organized by the IAEA and held at Ann Arbor, Michigan, USA, 17 - 21 July 1967. The meeting was attended by 143 participants from 24 Member States and one international organization. Contents: (Vol.I) Theory of neutron thermalization (15 papers); Scattering law (20 papers); Angular, space, temperature and time dependence of neutron spectra (9 papers). (Vol.II) Measurement of thermal neutron spectra and spectral indices, and comparison with theory (17 papers); Time-dependent problems in neutron thermalization (12 papers). Each paper is in its original language (61 English, 1 French and 11 Russian) and is preceded by an abstract in English with one in the original language if this is not English. Discussions are in English.

  10. Superfluid Brillouin Optomechanics

    CERN Document Server

    Kashkanova, A D; Brown, C D; Flowers-Jacobs, N E; Childress, L; Hoch, S W; Hohmann, L; Ott, K; Reichel, J; Harris, J G E

    2016-01-01

    Optomechanical systems couple an electromagnetic cavity to a mechanical resonator which is typically formed from a solid object. The range of phenomena accessible to these systems depends on the properties of the mechanical resonator and on the manner in which it couples to the cavity fields. In both respects, a mechanical resonator formed from superfluid liquid helium offers several appealing features: low electromagnetic absorption, high thermal conductivity, vanishing viscosity, well-understood mechanical loss, and in situ alignment with cryogenic cavities. In addition, it offers degrees of freedom that differ qualitatively from those of a solid. Here, we describe an optomechanical system consisting of a miniature optical cavity filled with superfluid helium. The cavity mirrors define optical and mechanical modes with near-perfect overlap, resulting in an optomechanical coupling rate ~3 kHz. This coupling is used to drive the superfluid; it is also used to observe the superfluid's thermal motion, resolving...

  11. Parity violation and electron scattering

    International Nuclear Information System (INIS)

    I have been asked to set stage for the more specialized talks to follow and to review the history of parity nonconservation in electron scattering. In electron scattering, parity violation (PV) is the unique signal which allows us to study the weak interactions among the much stronger electromagnetic ones. It is observed through the detection of a pseudoscalar quantity in the cross section or rate of a reaction. These pseudoscalars usually involve a spin or polarization. Since it is known that spin effects are more sensitive to dynamics than differential or total cross sections, which are partially determined by geometry, PV measurements allow us to learn about the weak interactions and nucleon and nuclear structure. Because the weak interactions are of short range, the measurements are sensitive to different aspects of the target structure than the long range electromagnetic scattering. 15 refs., 7 figs

  12. A microrod-resonator Brillouin laser with 240 Hz absolute linewidth

    CERN Document Server

    Loh, William; Cole, Daniel C; Coillet, Aurelien; Baynes, Fred N; Papp, Scott B; Diddams, Scott A

    2015-01-01

    We demonstrate an ultralow-noise microrod-resonator based laser that oscillates on the gain supplied by the stimulated Brillouin scattering optical nonlinearity. Microresonator Brillouin lasers are known to offer an outstanding frequency noise floor, which is limited by fundamental thermal fluctuations. Here, we show experimental evidence that thermal effects also dominate the close-to-carrier frequency fluctuations. The 6-mm diameter microrod resonator used in our experiments has a large optical mode area of ~100 {\\mu}m$^2$, and hence its 10 ms thermal time constant filters the close-to-carrier optical frequency noise. The result is an absolute laser linewidth of 240 Hz with a corresponding white-frequency noise floor of 0.1 Hz$^2$/Hz. We explain the steady-state performance of this laser by measurements of its operation state and of its mode detuning and lineshape. Our results highlight a mechanism for noise that is common to many microresonator devices due to the inherent coupling between intracavity power...

  13. Correlation between porosity and roughness as obtained by porous silicon nano surface scattering spectrum

    Directory of Open Access Journals (Sweden)

    R Dariani

    2015-01-01

    Full Text Available Reflection spectra of four porous silicon samples under etching times of 2, 6, 10, and 14 min with current density of 10 mA/cm2 were measured. Reflection spectra behaviors for all samples were the same, but their intensities were different and decreased by increasing the etching time. The similar behavior of reflection spectra could be attributed to the electrolyte solution concentration which was the same during fabrication and reduction of reflection spectrum due to the reduction of particle size. Also, the region for the lowest intensity at reflection spectra was related to porous silicon energy gap which shows blue shift for porous silicon energy gap. Roughness study of porous silicon samples was done by scattering spectra measurements, Rayleigh criteria, and Davis-Bennet equation. Scattering spectra of the samples were measured at 10, 15, and 20 degrees by using spectrophotometer. Reflected light intensity reduced by increasing the scattering angle except for the normal scattering which agreed with Rayleigh criteria. Also, our results showed that by increasing the etching time, porosity (sizes and numbers of pores increases and therefore light absorption increases and scattering from surface reduces. But since scattering varies with the observation scale (wavelength, the relationship between scattering and porosity differs by varying the observation scale (wavelength

  14. Study on the resonance light scattering spectra of the interaction of quinine dihydrochloride with perfluorooctane sulfonate and its analytical applications%盐酸奎宁与全氟辛烷磺酸体系的共振光散射光谱研究及其分析应用

    Institute of Scientific and Technical Information of China (English)

    吴飞; 谭克俊; 刘忠德

    2011-01-01

    研究了盐酸奎宁(Quinine dihydrochloride,简称Quinine)与全氟辛烷磺酸(perfluorooctane sulfonate,简称PFOS)相互作用的共振光散射(resonance light scattering,RLS)光谱,并建立了PFOS的共振光散射分析方法.在pH值为2.87的Britton-Robinson(BR)缓冲溶液中,全氟辛烷磺酸根阴离子与质子化的盐酸奎宁通过静电引力和疏水作用形成2:1的离子缔合物,引起共振光散射强度(IRLS)显著增强,最大散射波长位于283nm处,增强的散射信号强度与PFOS浓度在0.10-50.0μmol/L范围内呈线性关系,据此建立了测定PFOS的散射分析方法,检测限为9.88nmol/L.讨论了体系的最佳反应条件及外来物质的干扰,同时研究了体系的吸收光谱及荧光光谱,并探讨了反应机理.本方法用于水样及人体血清样品中PFOS的测定,RSD≤4.2%.%The resonance light scattering(RLS) spectra of the interaction Quinine dihydrochloride (Quinine)with perfluorooctane sulfonate (PFOS) was investigated. A RLS method for the determination of PFOS has been established. In pH 2.87 Britton-Robinson (BR) buffer solution, perfluorooctane sulfonate (PFOS) anions can react with the protonated Quinine by electrostatic forces and hydrophobic interactions to form 2:1 ion-association complexes and resulting in greatly enhanced resonance light scattering signals characterized by a peak at 283 nm, and the RLS intensity was proportional to the concentration of PFOS in the range of 0.10 ~ 5.00 μmol/L. The limit of detection is 9.88 nmol/L. In this paper, the optimum reaction conditions and the interference of foreign substances of the system were investigated. The absorption and fluorescence spectra of the system as well as the reaction mechanism were also discussed. This RLS method has been applied to the determination of PFOS in environmental samples and human serum samples with RSD ≤ 4.2%.

  15. Spectroscopy, scattering, and KK molecules

    International Nuclear Information System (INIS)

    The author presents a pedagogical description of a new theoretical technique, based on the multichannel Schroedinger equation, for simultaneously applying the quark model to both meson spectroscopy and meson-meson scattering. This is an extension of an earlier analysis which led to the prediction that the fo(975) and ao(980) scalar mesons are K bar K molecular states

  16. Soil emissivity and reflectance spectra measurements.

    Science.gov (United States)

    Sobrino, José A; Mattar, Cristian; Pardo, Pablo; Jiménez-Muñoz, Juan C; Hook, Simon J; Baldridge, Alice; Ibañez, Rafael

    2009-07-01

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer.

  17. A tunable multiwavelength Brillouin fiber laser with a semiconductor optical amplifier

    International Nuclear Information System (INIS)

    A multiwavelength Brillouin fiber laser with wavelength tunability using a semiconductor optical amplifier (SOA) and a birefringence fiber loop mirror has been demonstrated. The inhomogeneous broadening, and flat and broad gain in the SOA make the proposed multiwavelength laser comparatively stable and have the potential to generate a large number of Brillouin lasing wavelengths. A stable multiwavelength output with a spectral spacing of the Brillouin frequency shift of 0.08 nm and a wavelength number of more than 91 has been successfully produced. Moreover, wavelength tuning over a 21 nm wavelength range has been achieved. (paper)

  18. Rotational Spectra of the Baryons and Mesons

    CERN Document Server

    Akers, D

    2003-01-01

    An investigation of the rotational spectra of baryons and mesons is conducted. Diakonov, Petrov and Polyakov claimed that all light baryons are rotational excitations. A study of the history of particle physics indicates that the ideas of rotational spectra can be originally attributed to a constituent-quark (CQ) model as proposed by Mac Gregor. Later research advanced spin-orbit splitting in a deformed model as suggested by Bhaduri and others. In the present work, we show from current data that the rotational spectra of baryons and mesons are in agreement with the original claims of Mac Gregor: namely, the values for the rotational energies Erot of particles merge with those of nuclear rotational bands in light nuclei. It is also shown that particles of different isotopic spins are separated in mass by a 70 MeV quantum, which is related to the SU(3) decuplet mass spacing as originally proposed by Gell-Mann.

  19. Crossover from inelastic magnetic scattering of Cooper pairs to spin-wave dispersion produces the low-energy kink structure in the spectra of cuprate superconductors

    Science.gov (United States)

    Das, Tanmoy; Markiewicz, R. S.; Bansil, A.

    2012-04-01

    We present GW-based-self-energy calculations for the state of the coexisting spin-density-wave and d-wave superconductivity in a series of cuprate superconductors. The spin-resonance spectrum is found to exhibit the typical “hourglass” form whose upward and downward dispersion branches come from the gapped-spin-wave and magnetic scattering, of Cooper pairs, respectively. We show that the crossover between these two different dispersion features leads to an abrupt change of slope in the quasiparticle self-energy, and hence, the low-energy kink commences in the single-particle quasiparticle spectrum. The calculated electron-boson-coupling strength agrees well with experimental data as a function of temperature, doping, and material. The results demonstrate that electronic correlations dominate the quasiparticle spectra of cuprates near the low-energy kink, suggesting a relatively smaller role for phonons in this energy range.

  20. A new approach to measure the ocean temperature using Brillouin lidar

    Institute of Scientific and Technical Information of China (English)

    Wei Gao; Zhiwei Lü; Yongkang Dong; Weiming He

    2006-01-01

    @@ An approach of lidar measurements of ocean temperature through measuring the spectral linewidth of the backscattered Brillouin lines is presented. An empirical equation for the temperature as a function of Brillouin linewidth and salinity is derived. Theoretical results are in good agreement with the experimental data. The equation also reveals the dependence of the temperature on the salinity and Brillouin linewidth.It is shown that the uncertainty of the salinity has very little impact on the temperature measurement.The uncertainty of this temperature measurement methodology is approximately 0.02 ℃.

  1. Spectra of atoms and molecules

    CERN Document Server

    Bernath, Peter F

    2005-01-01

    1. Introduction. 1.1. Waves, Particles, and Units. 1.2. The Electromagnetic Spectrum. 1.3. Interaction of Radiation with Matter. 1.3a. Blackbody Radiation. 1.3b. Einstein A and B Coefficients. 1.3c. Absorption and Emission of Radiation. 1.3d. Beer''s Law. 1.3e. Lineshape Functions. 1.3f. Natural Lifetime Broadening. 1.3g. Pressure Broadening. 1.3h. Doppler Broadening. 1.3i. Transit-Time Broadening. 1.3j. Power Broadening. 2. Molecular Symmetry. 2.1. Symmetry Operations. 2.1a. Operator Algebra. 2.1b. Symmetry Operator Algebra. 2.2. Groups. 2.2a. Point Groups. 2.2b. Classes. 2.2c. Subgroups. 2.3. Notation for Point Groups. 3. Matrix Representation of Groups. 3.1. Vectors and Matrices. 3.1a. Matrix Eigenvalue Problem. 3.1b. Similarity Transformations. 3.2. Symmetry Operations and Position Vectors. 3.2a. Reflection. 3.2b. Rotation. 3.2c. Rotation-Reflection. 3.2d. Inversion. 3.2e. Identity. 3.3. Symmetry Operators and Basic Vectors. 3.4. Symmetry Operators and Basic Functions. 3.4a. Function Spaces. 3.4b. Gram-Sc...

  2. Vibrational properties and phonon anharmonicity in ZnS{sub 1−x}Se{sub x}: Inelastic neutron scattering, Raman scattering, X-ray diffraction measurements and lattice dynamical studies

    Energy Technology Data Exchange (ETDEWEB)

    Basak, Tista, E-mail: tistabasak1@gmail.com [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Rao, Mala N.; Chaplot, S.L.; Salke, Nilesh; Rao, Rekha [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Dhanasekaran, R. [Crystal Growth Centre, Anna University, SP Road, Chennai 600025 (India); Rajarajan, A.K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Rols, S. [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, Grenoble (France); Mittal, R.; Jayakrishnan, V.B.; Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)

    2014-01-15

    Inelastic neutron scattering, Raman and X-ray diffraction measurements coupled with lattice dynamical calculations (employing a semi-empirical transferable potential model) have been carried out to gain a detailed understanding of the peculiar vibrational spectrum exhibited by the mixed crystal ZnS{sub 1−x}Se{sub x}. Raman scattering measurements performed over a varying range of temperature (100–800 K) and pressure (up to 13 GPa) have confirmed that the additional mode observed in the spectra are visible over the entire range of temperature and pressure. Correlation of the individual motions of atoms (obtained from computed total and partial phonon density of states) with the inelastic neutron scattering measurements (carried out over the entire Brillouin zone) have then indicated that the existence of the additional mode in ZnS{sub 1−x}Se{sub x} is due to the vibrations of the Se atom being in resonance with that of the S atom. Further, it has been shown that the presence of this additional mode can be tuned by varying the mass of the atom at the Se site. In addition, an analysis of bond-length distribution with increasing Se concentration have elucidated that bond-length spread is not responsible for the presence of the additional mode. An analysis of the peak shifts of the Raman modes with temperature and pressure indicate that the anharmonicity of the vibrational modes increases with increasing compositional disorder. This is attributed to the fact that increasing Se concentration gives rise to a distribution of bond-lengths in ZnS{sub 1−x}Se{sub x}, which is responsible for this compositional disorder induced anharmonicity. Our computations have thus revealed that mass of the anion is responsible for the presence of additional mode while bond-length distribution gives rise to the existence of compositional disorder induced anharmonicity in ZnS{sub 1−x}Se{sub x}. Further, it is observed that the contribution of explicit anharmonicity to the total

  3. Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra

    CERN Document Server

    Morley, Caroline V; Marley, Mark S; Zahnle, Kevin; Line, Michael; Kempton, Eliza; Lewis, Nikole; Cahoy, Kerri

    2015-01-01

    Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features (Kreidberg et al. 2014b). We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000x solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (~400-800 K) planets can distinguish cloudy spectra, which have moderate ...

  4. Rotational Spectra of Phenylalanine, Tirosine and Tryptophan

    Science.gov (United States)

    Mata, S.; Perez, C.; Sanz, M. E.; Blanco, S.; López, J. C.; Alonso, J. L.

    2009-06-01

    The rotational spectra of the aromatic natural amino acids phenylalanine, tyrosine and tryptophan have been investigated by Laser Ablation Molecular Beam Fourier transform Microwave Spectroscopy LA-MB-FTMW. The spectra of two rotamers of phenylalanine have been detected in the supersonic expansion. Both forms are stabilized by a chain of intramolecular hydrogen bonds O-H\\cdotsN-H\\cdots{π}, being the carboxylic group incis configuration. One conformer of tyrosine, which only differs from phenylalanine in a -OH group inpara position, has been also characterized. Preliminary results on the rotational spectrum of tryptophan are presented.

  5. Beam quality improvement of pulsed Nd:YAG lasers using Brillouin phase conjugation

    Science.gov (United States)

    Eichler, Hans J.; Haase, Andreas; Hermann, S.; Menzel, Ralf; Schumann, D.

    1993-04-01

    Using phaseconjugating mirrors (PCMs) the beam quality of solid state lasers can be improved by compensating the thermal lens of the rods at high average powers. Oscillators with one PCM as a highly reflecting mirror and double-pass amplifiers with PCMs have been investigated. PCMs are realized by stimulated Brillouin scattering (SBS). Nd:YAG and Nd,Cr:GSGG oscillators have been built with pulse repetition rates up to 45 Hz. Stable TEM00-mode operation has been obtained. Average output powers of 10 watts for 15 ns Q-switched pulses of a Nd:YAG laser and 7 watts for Nd,Cr:GSGG have been achieved. In a double pass Nd:YAG amplifier the thermal lens was compensated leading to a nearly diffraction limited beam with a maximum output power of 40 watts.

  6. Leveraging High Resolution Spectra to Understand the Disk and Relativistic Iron Line of Cygnus X-1

    Science.gov (United States)

    Nowak, M.; Wilms, J.; Pottschmidt, K.; Grinberg, V.; Schulz, N.; Corrales, L.

    2016-06-01

    In April 2008 we conducted an observation of the black hole candidate Cygnus X-1 that was performed simultaneously with every X-ray and gamma-ray satellite flying at that time, including Chandra-HETG. The HETG spectra are crucial for modeling the ionized absorbtion from the "focused-wind" of the secondary, which is present and must be accounted for in all of our spectra. These features, however, are unresolved in the non-gratings instruments (e.g., RXTE, Suzaku, Swift, XMM-EPIC, INTEGRAL). Similarly, we must account for differences in spatial resolution. The X-ray scattering dust halo, which is usually ignored in most analyses, is spatially resolved in the Chandra and XMM-Newton spectra, but is unresolved in the other instruments. Thus one must account for dust scattering loss in the high spatial resolution spectra, and the scattering back into our line of site for the low resolution spectra. In this work, we attempt to arrive at a joint model for these spectra, and further comment on the cross calibration of each of the X-ray instruments participating in this campaign.

  7. Experimental Effects on IR Reflectance Spectra: Particle Size and Morphology

    Energy Technology Data Exchange (ETDEWEB)

    Beiswenger, Toya N.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; Blake, Thomas A.; Ertel, Alyssa B.; Tonkyn, Russell G.; Szecsody, James E.; Johnson, Timothy J.; Smith, Milton; Lanker, Cory

    2016-05-23

    For geologic and extraterrestrial samples it is known that both particle size and morphology can have strong effects on the species’ infrared reflectance spectra. Due to such effects, the reflectance spectra cannot be predicted from the absorption coefficients alone. This is because reflectance is both a surface as well as a bulk phenomenon, incorporating both dispersion as well as absorption effects. The same spectral features can even be observed as either a maximum or minimum. The complex effects depend on particle size and preparation, as well as the relative amplitudes of the optical constants n and k, i.e. the real and imaginary components of the complex refractive index. While somewhat oversimplified, upward-going amplitude in the reflectance spectrum usually result from surface scattering, i.e. rays that have been reflected from the surface without penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. While the effects are well known, we report seminal measurements of reflectance along with quantified particle size of the samples, the sizing obtained from optical microscopy measurements. The size measurements are correlated with the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to understand the effects on the spectral features as a function of the mean grain size of the sample. We report results for both sodium sulfate Na2SO4 as well as ammonium sulfate (NH4)2SO4; the optical constants have been measured for (NH4)2SO4. To go a step further from the field to the laboratory we explore our understanding of particle size effects on reflectance spectra in the field using standoff detection. This has helped identify weaknesses and strengths in detection using standoff distances of up 160 meters away from the Target. The studies have

  8. Robust, Brillouin Active Embedded Fiber-Is-The-Sensor System in Smart Composite Structures

    Science.gov (United States)

    Yu, Chung

    1996-01-01

    Extensive review of our proposed sensing scheme, based mainly on the forward Guided Acoustic Wave Brillouin Scattering (GAWBS) with backward stimulated Brillouin scattering (sBs) as an auxiliary scheme for system fault tolerance has been completed during this project period. This preliminary study is conducted for a number of reasons. The most significant reasons lie in the essential capability of the system to measure temperature and pressure. These two measurands have been proposed to be sensed by sBs in our proposal. Temperature and pressure/strain are important measurands in structural monitoring, so that the effectiveness of sensing by sBs needs to be further examined. It has been pointed out initially that sBs shift will be dependent on temperature and pressure/strain simultaneously. The shift versus temperature or strain is linear. Now, the question is how can these two measurands be separated when sBs is used to sense an environment, in which both temperature and strain are changing simultaneously. Typical sBs shift plotted versus strain and varying temperature is shown in Fig. 1. As is clear, a fiber initially stressed will relax with rising temperature. This is verified by a displacement to the right with rising temperature of the sBs shift vs strain curves in the figure. A way to circumvent this ambiguity is by employing two fibers, one pre-stressed and the other is a free fiber. The latter will measure temperature and subtracting data in the latter fiber from those of the former will give us net strain readings. This is a laborious approach, since it involves the use of two identical fibers, and this is hard to accomplish, especially when many sensors are needed. Additional multiplexing of the data stream for data subtraction becomes a necessity.

  9. Spectroscopy, scattering, and KK molecules

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J. [Univ. of Mississippi, University, MS (United States)

    1994-04-01

    The author presents a pedagogical description of a new theoretical technique, based on the multichannel Schroedinger equation, for simultaneously applying the quark model to both meson spectroscopy and meson-meson scattering. This is an extension of an earlier analysis which led to the prediction that the f{sub o}(975) and a{sub o}(980) scalar mesons are K{bar K} molecular states.

  10. Chiral recognition in electron scattering by S- and R-2-butanol

    DEFF Research Database (Denmark)

    Jones, Nykola C.; Hoffmann, Søren Vrønning; Field, David

    2015-01-01

    Experiments are described involving the low energy scattering of electrons from the two optical enantiomers S- and R- 2-butanol. Using a synchrotron radiation photoionization source on the ASTRID storage ring, scattering spectra are reported between a few meV and 140 meV at an electron energy...

  11. Comparative Studies of Slow Neutron Scattering by Solid and Liquid Tin

    International Nuclear Information System (INIS)

    The scattering of 4.0A and 6.2A neutrons by tin as solid (210oC) and liquid (240oC) has been measured. The scattered spectra at six scatter angles between 20o and 90o was analysed by titne-of-flight methods. At the longer wavelength the low intensity elastic scattered peaks are used to derive the incoherent cross-section for tin (0.04 ± 0.01 b ). Sharp steps in scattered spectra for the solid can be identified and similar but broadened steps for the liquid are seen. Using a theory due to Egelstaff, the steps for the solid can be interpreted as the excitation of particular phonons. The single phonon theory for the solid is modified to attempt to account for the different behaviour of the liquids The appreciable scattering observed in the liquid at low energy transfers is not explained in this way. (author)

  12. Single-end simultaneous temperature and strain sensing techniques based on Brillouin optical time domain reflectometry in few-mode fibers.

    Science.gov (United States)

    Weng, Yi; Ip, Ezra; Pan, Zhongqi; Wang, Ting

    2015-04-01

    Recently there is a growing interest in developing few-mode fiber (FMF) based distributed sensors, which can attain higher spatial resolution and sensitivity compared with the conventional single-mode approaches. However, current techniques require two lightwaves injected into both ends of FMF, resulting in their complicated setup and high cost, which causes a big issue for geotechnical and petroleum applications. In this paper, we present a single-end FMF-based distributed sensing system that allows simultaneous temperature and strain measurement by Brillouin optical time-domain reflectometry (BOTDR) and heterodyne detection. Theoretical analysis and experimental assessment of multi-parameter discriminative measurement techniques applied to distributed FMF sensors are presented. Experimental results confirm that FM-BOTDR has similar performance with two-end methods such as FM-BOTDA, but with simpler setup and lower cost. The temperature-induced expansion strain (TIES) in response to different modes is discussed as well. Furthermore, we optimized the FMF design by exploiting modal profile and doping concentration, which indicates up to fivefold enhancement in measurement accuracy. This novel distributed FM-sensing system endows with good sensitivity characteristics and can prevent catastrophic failure in many applications. PMID:25968738

  13. The mechanical properties of a nanocrystalline Al2O3/a-Al2O3 composite coating measured by nanoindentation and Brillouin spectroscopy

    International Nuclear Information System (INIS)

    In this work, ellipsometry, Brillouin spectroscopy and nanoindentation are combined to assess the mechanical properties of a nanocrystalline Al2O3/a-Al2O3 composite coating with high accuracy and precision. The nanocomposite is grown by pulsed laser deposition at either room temperature or 600 °C. The adhesive strength is evaluated by nanoscratch tests. In the room temperature process the coating attains an unusual combination of compactness, strong interfacial bonding, moderate stiffness (E = 195 ± 9 GPa and ν = 0.29 ± 0.02) and significant hardness (H = 10 ± 1 GPa), resulting in superior plastic behavior and a relatively high ratio of hardness to elastic modulus (H/E = 0.049). These features are correlated to the nanostructure of the coating, which comprises a regular dispersion of ultrafine crystalline Al2O3 nanodomains (2–5 nm) in a dense and amorphous alumina matrix, as revealed by transmission electron microscopy. For the coating grown at 600 °C, strong adhesion is also observed, with an increase of stiffness and a significant enhancement of hardness (E = 277 ± 9 GPa, ν = 0.27 ± 0.02 and H = 25 ± 1 GPa), suggesting an outstanding resistance to wear (H/E = 0.091)

  14. Electronic structure in a one-Fe Brillouin zone of the iron pnictide superconductors CsFe2As2 and RbFe2As2

    Science.gov (United States)

    Kong, S.; Liu, D. Y.; Cui, S. T.; Ju, S. L.; Wang, A. F.; Luo, X. G.; Zou, L. J.; Chen, X. H.; Zhang, G. B.; Sun, Z.

    2015-11-01

    Using angle-resolved photoemission spectroscopy, we studied the electronic structures of CsFe2As2 and RbFe2As2 . Contrary to other iron-based superconductors where the band structures are usually depicted in the two-Fe Brillouin zone (BZ), we found that the distribution of electronic spectral weight in CsFe2As2 and RbFe2As2 follows the one-Fe BZ, and that the emerging band structure is qualitatively consistent with theoretical band calculations of the one-Fe BZ except for some shadow band effect. Our data suggest that the interlayer separation is an important tuning factor for the physics of FeAs layers, the increase of which can reduce the coupling between Fe and As and lead to the emergence of the electronic structure in accord with the one-Fe symmetry of the Fe square lattice. Our finding puts strong constraints on the theoretical models constructed on the basis of the one-Fe BZ.

  15. Atomic and Molecular Aspects of Astronomical Spectra

    OpenAIRE

    Sochi, T.

    2012-01-01

    In the first section of this thesis, we present the atomic part of our investigation. A C2+ atomic target was prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. The R-matrix method of electron scattering theory was used to describe the C2+ plus electron system. Theoretical data concerning bound and autoionizing states...

  16. Raman scattering and anomalous Stokes–anti-Stokes ratio in MoTe2 atomic layers

    Science.gov (United States)

    Goldstein, Thomas; Chen, Shao-Yu; Tong, Jiayue; Xiao, Di; Ramasubramaniam, Ashwin; Yan, Jun

    2016-06-01

    Stokes and anti-Stokes Raman scattering are performed on atomic layers of hexagonal molybdenum ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor. The data reveal all six types of zone center optical phonons, along with their corresponding Davydov splittings, which have been challenging to see in other TMDCs. We discover that the anti-Stokes Raman intensity of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain experimental conditions, and find the effect to be tunable by excitation frequency and number of atomic layers. These observations are interpreted as a result of resonance effects arising from the C excitons in the vicinity of the Brillouin zone center in the photon-electron-phonon interaction process.

  17. Raman scattering and anomalous Stokes-anti-Stokes ratio in MoTe2 atomic layers.

    Science.gov (United States)

    Goldstein, Thomas; Chen, Shao-Yu; Tong, Jiayue; Xiao, Di; Ramasubramaniam, Ashwin; Yan, Jun

    2016-01-01

    Stokes and anti-Stokes Raman scattering are performed on atomic layers of hexagonal molybdenum ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor. The data reveal all six types of zone center optical phonons, along with their corresponding Davydov splittings, which have been challenging to see in other TMDCs. We discover that the anti-Stokes Raman intensity of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain experimental conditions, and find the effect to be tunable by excitation frequency and number of atomic layers. These observations are interpreted as a result of resonance effects arising from the C excitons in the vicinity of the Brillouin zone center in the photon-electron-phonon interaction process. PMID:27324297

  18. Multi-zone temperature sensor using a multi-wavelength Brillouin fiber ring laser

    OpenAIRE

    Galíndez Jamioy, Carlos Augusto; Madruga Saavedra, Francisco Javier; Ullán Nieto, Ángel; López Amo, Manuel; López Higuera, José Miguel

    2009-01-01

    A simple system for sensing temperature in multiple zones based on a multi-wavelength Brillouin fiber laser ring is presented. Optical fiber reels are serially concatenated and divided in zones (one per sensing area). Setting the Brillouin lasing in each spool of fiber generates a characteristic wavelength that depends on the fiber properties and the temperature in the zone. Thus, it is possible to measure temperature independently and accurately through heterodyne detection between two narro...

  19. POLLUX: a database of stellar spectra - First step : SED and High Resolution Synthetic Spectra

    Science.gov (United States)

    Palacios, A.; Josselin, E.; Lèbre, A.; Martins, F.; Monier, R.; Plez, B.; Belmas, M.

    2008-10-01

    POLLUX is a stellar spectra database under development at the GRAAL laboratory (Montpellier, France). It will be made available on-line to the community through a VO compliant interface (http://pollux.graal.univ-montp2.fr). In its first version, POLLUX will propose theoretical data: high resolution synthetic spectra and spectral energy distribution.

  20. Elastic scattering by hot electrons and apparent lifetime of longitudinal optical phonons in gallium nitride

    Science.gov (United States)

    Khurgin, Jacob B.; Bajaj, Sanyam; Rajan, Siddharth

    2015-12-01

    Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, the saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.

  1. Elastic scattering by hot electrons and apparent lifetime of longitudinal optical phonons in gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Khurgin, Jacob B., E-mail: jakek@jhu.edu [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Bajaj, Sanyam; Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-12-28

    Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, the saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.

  2. First numerical experiences with overlap fermions based on the Brillouin kernel

    CERN Document Server

    Durr, Stephan

    2016-01-01

    Numerical experiences are reported with overlap fermions which employ the Brillouin action as a kernel. After discussing the dispersion relations of both the kernel and the resulting chiral action, some of the physics features are addressed on quenched backgrounds. We find that the overlap with Brillouin kernel is much better localized than the overlap with Wilson kernel. Also a preliminary account is given of the cost of the formulation, in terms of CPU time and memory.

  3. Classical and quantum scattering in optical systems

    NARCIS (Netherlands)

    Puentes, Graciana

    2007-01-01

    The central topic of the Thesis concerns light scattering experiments with entangled photons. Specifically, we study the effect of scattering processes on polarization-entanglement of twin-photons. The main idea is that scattering generally couples polarization and spatial degrees of freedom of pho

  4. Scattering by two spheres: Theory and experiment

    DEFF Research Database (Denmark)

    Bjørnø, Irina; Jensen, Leif Bjørnø

    1998-01-01

    on three issues: (1) to develop a simplified theory for scattering by two elastical spheres; (2) to measure the scattering by two spheres in a water tank, and (3) to compare the theoretical/numerical results with the measured data. A number of factors influencing multiple scattering, including...

  5. Anomalies in the sound velocities of [011]-oriented Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals studied by using Brillouin light scattering

    Science.gov (United States)

    Kim, Tae Hyun; Kojima, Seiji; Ko, Jae-Hyeon

    2016-06-01

    The acoustic properties of [011]-oriented Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals were studied by using Brillouin spectroscopy over a wide temperature range under unpoled and poled conditions. Poling the crystal along the [011] direction induced significant changes in the sound velocity and the acoustic attenuation coefficient of both the longitudinal and the transverse acoustic modes at several characteristic temperatures. These acoustic anomalies could be attributed to changes in the polar character from macroscopic ferroelectric domains to mesoscopic polar regions along with quasi-static polar nanoregions and then to dynamic polar nanoregions upon heating the poled crystal.

  6. High-resolution Brillouin analysis in a carbon-fiber-composite unmanned aerial vehicle model wing

    Science.gov (United States)

    Stern, Yonatan; London, Yosef; Preter, Eyal; Antman, Yair; Shlomi, Orel; Silbiger, Maayan; Adler, Gadi; Zadok, Avi

    2016-05-01

    Standard optical fibers are successfully embedded within a model wing of an unmanned aerial vehicle, constructed of carbon fiber and epoxy, during its production. Time-gated Brillouin optical correlation domain analysis along the embedded optical fibers is performed with a spatial resolution of 4 cm. Tests were carried out using a portable measurement setup prototype. The results represent an important step towards applications of high-resolution Brillouin analysis outside the research laboratory.

  7. Understanding the baryon and meson spectra

    Energy Technology Data Exchange (ETDEWEB)

    Pennington, Michael R. [JLAB

    2013-10-01

    A brief overview is given of what we know of the baryon and meson spectra, with a focus on what are the key internal degrees of freedom and how these relate to strong coupling QCD. The challenges, experimental, theoretical and phenomenological, for the future are outlined, with particular reference to a program at Jefferson Lab to extract hadronic states in which glue unambiguously contributes to their quantum numbers.

  8. Thermal Emission and Reflected Light Spectra of Super Earths with Flat Transmission Spectra

    Science.gov (United States)

    Morley, Caroline V.; Fortney, Jonathan J.; Marley, Mark S.; Zahnle, Kevin; Line, Michael; Kempton, Eliza; Lewis, Nikole; Cahoy, Kerri

    2015-12-01

    Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000× solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (˜400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (˜200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳ 1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R ˜ 105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.

  9. Dose spectra from energetic particles and neutrons

    Science.gov (United States)

    Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

    2013-10-01

    spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

  10. Atomic and Molecular Aspects of Astronomical Spectra

    CERN Document Server

    Sochi, Taha

    2012-01-01

    In the first section we present the atomic part where a C2+ atomic target was prepared and used to generate theoretical data to investigate recombination lines arising from electron-ion collisions in thin plasma. R-matrix method was used to describe the C2+ plus electron system. Theoretical data concerning bound and autoionizing states were generated in the intermediate-coupling approximation. The data were used to generate dielectronic recombination data for C+ which include transition lines, oscillator strengths, radiative transition probabilities, emissivities and dielectronic recombination coefficients. The data were cast in a line list containing 6187 optically-allowed transitions which include many C II lines observed in astronomical spectra. This line list was used to analyze the spectra from a number of astronomical objects, mainly planetary nebulae, and identify their electron temperature. The electron temperature investigation was also extended to include free electron energy analysis to investigate...

  11. Raman Spectra of Methane, Ethylene, Ethane, Dimethyl ether, Formaldehyde and Propane for Combustion Applications

    KAUST Repository

    Magnotti, G.

    2015-05-09

    Spontaneous Raman scattering measurements of temperature and major species concentration in hydrocarbon-air flames require detailed knowledge of the Raman spectra of the hydrocarbons present when fuels more complex than methane are used. Although hydrocarbon spectra have been extensively studied at room temperature, there are no data available at higher temperatures. Quantum mechanical calculations, when available are not sufficiently accurate for combustion applications. This work presents experimental measurements of spontaneous Stokes-Raman scattering spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane in the temperature range 300-860 K. Raman spectra from heated hydrocarbons jets have been collected with a higher resolution than is generally employed for Raman measurements in combustion applications. A set of synthetic spectra have been generated for each hydrocarbon, providing the basis for extrapolation to higher temperatures. The spectra provided here will enable simultaneous measurements of multiple hydrocarbons in flames. This capability will greatly extend the range of applicability of Raman measurements in combustion applications. In addition, the experimental spectra provide a validation dataset for quantum mechanical models.

  12. Inflation and alternatives with blue tensor spectra

    International Nuclear Information System (INIS)

    We study the tilt of the primordial gravitational waves spectrum. A hint of blue tilt is shown from analyzing the BICEP2 and POLARBEAR data. Motivated by this, we explore the possibilities of blue tensor spectra from the very early universe cosmology models, including null energy condition violating inflation, inflation with general initial conditions, and string gas cosmology, etc. For the simplest G-inflation, blue tensor spectrum also implies blue scalar spectrum. In general, the inflation models with blue tensor spectra indicate large non-Gaussianities. On the other hand, string gas cosmology predicts blue tensor spectrum with highly Gaussian fluctuations. If further experiments do confirm the blue tensor spectrum, non-Gaussianity becomes a distinguishing test between inflation and alternatives

  13. Soil emissivity and reflectance spectra measurements

    International Nuclear Information System (INIS)

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 μm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer.

  14. Soil emissivity and reflectance spectra measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sobrino, Jose A.; Mattar, Cristian; Pardo, Pablo; Jimenez-Munoz, Juan C.; Hook, Simon J.; Baldridge, Alice; Ibanez, Rafael

    2009-07-01

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 {mu}m with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer.

  15. Soil emissivity and reflectance spectra measurements.

    Science.gov (United States)

    Sobrino, José A; Mattar, Cristian; Pardo, Pablo; Jiménez-Muñoz, Juan C; Hook, Simon J; Baldridge, Alice; Ibañez, Rafael

    2009-07-01

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer. PMID:19571921

  16. Brillouin microspectroscopy of nanostructured biomaterials: photonics assisted tailoring mechanical properties

    Science.gov (United States)

    Meng, Zhaokai; Jaiswal, Manish K.; Chitrakar, Chandani; Thakur, Teena; Gaharwar, Akhilesh K.; Yakovlev, Vladislav V.

    2016-03-01

    Developing new biomaterials is essential for the next-generation of materials for bioenergy, bioelectronics, basic biology, medical diagnostics, cancer research, and regenerative medicine. Specifically, recent progress in nanotechnology has stimulated the development of multifunctional biomaterials for tissue engineering applications. The physical properties of nanocomposite biomaterials, including elasticity and viscosity, play key roles in controlling cell fate, which underlines therapeutic success. Conventional mechanical tests, including uniaxial compression and tension, dynamic mechanical analysis and shear rheology, require mechanical forces to be directly exerted onto the sample and therefore may not be suitable for in situ measurements or continuous monitoring of mechanical stiffness. In this study, we employ spontaneous Brillouin spectroscopy as a viscoelasticity-specific probing technique. We utilized a Brillouin spectrometer to characterize biomaterial's microscopic elasticity and correlated those with conventional mechanical tests (e.g., rheology).

  17. Wave propagation and scattering in random media

    CERN Document Server

    Ishimaru, Akira

    1978-01-01

    Wave Propagation and Scattering in Random Media, Volume 2, presents the fundamental formulations of wave propagation and scattering in random media in a unified and systematic manner. The topics covered in this book may be grouped into three categories: waves in random scatterers, waves in random continua, and rough surface scattering. Random scatterers are random distributions of many particles. Examples are rain, fog, smog, hail, ocean particles, red blood cells, polymers, and other particles in a state of Brownian motion. Random continua are the media whose characteristics vary randomly an

  18. All-optical signal processing using dynamic Brillouin gratings

    Science.gov (United States)

    Santagiustina, Marco; Chin, Sanghoon; Primerov, Nicolay; Ursini, Leonora; Thévenaz, Luc

    2013-01-01

    The manipulation of dynamic Brillouin gratings in optical fibers is demonstrated to be an extremely flexible technique to achieve, with a single experimental setup, several all-optical signal processing functions. In particular, all-optical time differentiation, time integration and true time reversal are theoretically predicted, and then numerically and experimentally demonstrated. The technique can be exploited to process both photonic and ultra-wide band microwave signals, so enabling many applications in photonics and in radio science. PMID:23549159

  19. The Transit Spectra of Earth and Jupiter

    CERN Document Server

    Irwin, Patrick G J; Bowles, Neil E; Fletcher, Leigh N; Aigrain, Suzanne; Lee, Jae-Min

    2014-01-01

    In recent years, a number of observations have been made of the transits of 'Hot Jupiters', such as HD 189733b, which have been modelled to derive atmospheric structure and composition. As measurement techniques improve, the transit spectra of 'Super-Earths' such as GJ 1214b are becoming better constrained, allowing model atmospheres to be fitted for this class of planet also. While it is not yet possible to constrain the atmospheric states of small planets such as the Earth or cold planets like Jupiter, this may become practical in the coming decades and if so, it is of interest to determine what we might infer from such measurements. Here we have constructed atmospheric models of the Solar System planets from 0.4 - 15.5 microns that are consistent with ground-based and satellite observations and from these calculate the primary transit and secondary eclipse spectra (with respect to the Sun and typical M-dwarfs) that would be observed by a 'remote observer', many light years away. From these spectra we test ...

  20. IR, Raman and SERS spectra of propantheline bromide.

    Science.gov (United States)

    Baraldi, C; Freguglia, G; Tinti, A; Sparta, M; Alexandrova, A N; Gamberini, M C

    2013-02-15

    The two known propantheline bromide polymorphs (form I and form II) were studied and characterized by a multianalytical approach. In the present work, the identification of propantheline bromide polymorphic forms through vibrational IR spectroscopies are presented and for the first time Raman microscopy and hot stage Raman microscopy (HSRM) studies are reported. Finally, quantum mechanical calculations were performed. For assisting the assignment of the experimental picks, the two IR spectra of the most and least stable representatives of a set of 56 conformers are calculated and studied. DSC thermograms data, are also reported. The surface enhanced Raman scattering (SERS) spectrum was also recorded in a silver colloid; it could be inferred that propantheline bromide is adsorbed on silver colloid through the oxygen atom with the molecular plane perpendicular to the metal surface.