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Sample records for brillouin scattering and spectra

  1. 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.

  2. 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.

  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. Temperature Dependence of Brillouin Light Scattering Spectra of Acoustic Phonons in Silicon

    Science.gov (United States)

    Somerville, Kevin; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin

    2015-03-01

    Thermal management represents an outstanding challenge in many areas of technology. Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. Interest in non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report temperature dependent BLS spectra of silicon, with Raman spectra taken simultaneously for comparison. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons. We determine that the integrated BLS intensity can be used measure the temperature of specific acoustic phonon modes. This work is supported by National Science Foundation (NSF) Thermal Transport Processes Program under Grant CBET-1336968.

  5. Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

    International Nuclear Information System (INIS)

    Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons

  6. Shear Brillouin light scattering microscope.

    Science.gov (United States)

    Kim, Moonseok; Besner, Sebastien; Ramier, Antoine; Kwok, Sheldon J J; An, Jeesoo; Scarcelli, Giuliano; Yun, Seok Hyun

    2016-01-11

    Brillouin spectroscopy has been used to characterize shear acoustic phonons in materials. However, conventional instruments had slow acquisition times over 10 min per 1 mW of input optical power, and they required two objective lenses to form a 90° scattering geometry necessary for polarization coupling by shear phonons. Here, we demonstrate a confocal Brillouin microscope capable of detecting both shear and longitudinal phonons with improved speeds and with a single objective lens. Brillouin scattering spectra were measured from polycarbonate, fused quartz, and borosilicate in 1-10 s at an optical power level of 10 mW. The elastic constants, phonon mean free path and the ratio of the Pockels coefficients were determined at microscopic resolution. PMID:26832263

  7. THE INTERFACE POLYCARBONATE-GLASS : A THEORETICAL STUDY OF BRILLOUIN SPECTRA AND PHOTOELASTIC PROPERTIES

    OpenAIRE

    Nizzoli, F.; A Franchini; Santoro, G.

    1984-01-01

    We present calculations of surface waves and Brillouin scattering intensity for polycarbonate films supported by a pyrex substrate in the thickness range 0-0.6 µm. Comparison between calculated and experimental spectra shows that it is possible to obtain accurate information concerning the thickness of the film and the value and sign of the photoelastic constants.

  8. Brillouin amplification and processing of the Rayleigh scattered signal.

    Science.gov (United States)

    Mermelstein, David; Shacham, Eliashiv; Biton, Moran; Sternklar, Shmuel

    2015-07-15

    Brillouin amplification of Rayleigh scattering is demonstrated using two different configurations. In the first technique, the Rayleigh scattering and amplification occurs simultaneously in the same fiber. In the second technique, the amplification takes place in a second fiber. The differences between the two techniques are delineated. Using the second technique, we demonstrate single-sideband off-resonant Brillouin amplification of the Rayleigh signal. This technique is shown to enhance the SNR of a signal that is due to vibration-induced strain on the fiber. PMID:26176464

  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. 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

  12. 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.

  13. 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...

  14. 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...

  15. 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.

  16. Acoustic confinement and Stimulated Brillouin Scattering in integrated optical waveguides

    CERN Document Server

    Poulton, Christopher G; Eggleton, Benjamin J

    2013-01-01

    We examine the effect of acoustic mode confinement on Stimulated Brillouin Scattering in optical waveguides that consist of a guiding core embedded in a solid substrate. We find that SBS can arise due to coupling to acoustic modes in three different regimes. First, the acoustic modes may be guided by total internal reflection; in this case the SBS gain depends directly on the degree of confinement of the acoustic mode in the core, which is in turn determined by the acoustic V-parameter. Second, the acoustic modes may be leaky, but may nevertheless have a sufficiently long lifetime to have a large effect on the SBS gain; the lifetime of acoustic modes in this regime depends not only on the contrast in acoustic properties between the core and the cladding, but is also highly dependent on the waveguide dimensions. Finally SBS may occur due to coupling to free modes, which exist even in the absence of acoustic confinement; we find that the cumulative effect of coupling to these non-confined modes results in signi...

  17. 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...

  18. 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)

  19. Suppression of stimulated Brillouin scattering in high power fibre lasers and amplifiers

    OpenAIRE

    Hernandez-Solis, Vladimir

    2009-01-01

    Fibre sources in high power devices have significant advantages over conventional gas and solid state lasers. However, for applications that require the so-called singlefrequency sources with narrow linewidths, the output power is low mainly because of the problem of the stimulated Brillouin scattering (SBS). A model that accounts for the SBS in dual-clad fibre lasers and amplifiers is presented. This was carried out in order to study the key parameters that affect the Brillouin threshold...

  20. Localized and stationary dynamic gratings via stimulated Brillouin scattering with phase modulated pumps

    OpenAIRE

    Antman, Yair; Primerov, Nikolay; Sancho Dura, Juan; Thévenaz, Luc; Zadok, Avinoam

    2012-01-01

    A novel technique for the localization of stimulated Brillouin scattering (SBS) interaction is proposed, analyzed and demonstrated experimentally. The method relies on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS), these waves being spectrally detuned by the Brillouin frequency shift. The PRBS symbol duration is much shorter than the acoustic lifetime. The interference between the two modulated waves gives rise to an acoustic grati...

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. Simulation of stimulated Brillouin scattering and stimulated Raman scattering in shock ignition

    Science.gov (United States)

    Hao, L.; Li, J.; Liu, W. D.; Yan, R.; Ren, C.

    2016-04-01

    We study stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) in shock ignition by comparing fluid and particle-in-cell (PIC) simulations. Under typical parameters for the OMEGA experiments [Theobald et al., Phys. Plasmas 19, 102706 (2012)], a series of 1D fluid simulations with laser intensities ranging between 2 × 1015 and 2 × 1016 W/cm2 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 0.17nc to be less than 3.5 × 1015 W/cm2. 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.

  6. 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.

  7. 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).

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. Brillouin scattering in glass-forming liquids: q-dependent linewidths and the generalized viscosity

    International Nuclear Information System (INIS)

    Recently, Gomperts, Variyar, and Kivelson [J. Chem. Phys. 98, 31 (1993)] analyzed Brillouin linewidth data for triphenylphosphite and found a striking wave vector dependence which varied strongly with temperature. We present a simple explanation based on a Debye relaxation model from which results similar to theirs are obtained even though the longitudinal viscosity has no intrinsic wave vector dependence. We also explore the quantitative differences between their results and those obtained with the Debye model, and show that these differences can be explained by the two-step structural realaxation dynamics predicted by mode coupling theory and observed in recent neutron- and light-scattering experiments

  16. 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.

  17. 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.

  18. 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...

  19. Optimized determination of elastic constants of crystals and their uncertainties from surface Brillouin scattering.

    Science.gov (United States)

    Every, A G; Sumanya, C; Mathe, B A; Zhang, X; Comins, J D

    2016-07-01

    Surface Brillouin scattering of light allows the angular-dependent velocities of Rayleigh surface acoustic waves (SAW), pseudo-SAW and longitudinal lateral waves (L) on the surface of an opaque crystal to be measured, and the elastic constants thereby determined. Closed form expressions exist for the surface wave velocities in high symmetry directions on crystallographic symmetry planes, and these have been exploited in the past for obtaining the values of the elastic constants. This paper describes a procedure for obtaining an optimized set of elastic constants from SAW, pseudo-SAW and L velocities measured in arbitrary directions in the (001) and (110) surfaces of cubic crystals. It does so by affecting a linearization of the numerically determined angular-dependent SAW and pseudo-SAW velocities near the best fit, and using analytic expressions for the L velocity. The method also generates covariance ellipsoids, from which the uncertainties in the determined values of the elastic constants can be read off. The method is illustrated using surface Brillouin scattering data to obtain the room-temperature elastic constants C11, C12 and C44 of the cubic crystals VC0.75 and Rh3Nb. PMID:26899728

  20. 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.

  1. 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...

  2. 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.

  3. Localized and stationary dynamic gratings via stimulated Brillouin scattering with phase modulated pumps.

    Science.gov (United States)

    Antman, Y; Primerov, N; Sancho, J; Thevenaz, L; Zadok, A

    2012-03-26

    A novel technique for the localization of stimulated Brillouin scattering (SBS) interaction is proposed, analyzed and demonstrated experimentally. The method relies on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS), these waves being spectrally detuned by the Brillouin frequency shift. The PRBS symbol duration is much shorter than the acoustic lifetime. The interference between the two modulated waves gives rise to an acoustic grating that is confined to narrow correlation peaks, as short as 1.7 cm. The separation between neighboring peaks, which is governed by the PRBS length, can be made arbitrarily long. The method is demonstrated in the generation and applications of dynamic gratings in polarization maintaining (PM) fibers. Localized and stationary acoustic gratings are induced by two phase modulated pumps that are polarized along one principal axis of the PM fiber, and interrogated by a third, readout wave which is polarized along the orthogonal axis. Using the proposed technique, we demonstrate the variable delay of 1 ns-long readout pulses by as much as 770 ns. Noise due to reflections from residual off-peak gratings and its implications on the potential variable delay of optical communication data are discussed. The method is equally applicable to the modulation of pump and probe waves in SBS over standard fibers. PMID:22453458

  4. 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.

  5. 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.

  6. Time-dependent filamentation and stimulated Brillouin forward scattering in inertial confinement fusion plasmas

    International Nuclear Information System (INIS)

    Numerical simulations of the temporal evolution of laser light filamentation and stimulated Brillouin forward scattering (SBFS) in plasmas, under conditions that are relevant to laser fusion, are presented and analyzed. Long term unsteady behavior of filaments is observed to be the norm. Temporal and spatial incoherence due to filamentation and SBFS are impressed upon time-independent incident laser beams. The bandwidth and angular divergence imposed upon the beam increase with the strength of the interaction. In addition, the spectrum of the transmitted light is redshifted by an amount that increases with the interaction strength. Spectral analysis of the transmitted light reveals that SBFS plays a role in the generation of the observed temporal incoherence. Incident beams with some spatial incoherence but no temporal smoothing are compared to those with ab initio temporal beam smoothing (TBS). Under typical conditions, TBS beams will undergo far less angular and spectral spreading and far less SBFS than unsmoothed beams

  7. 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...

  8. Surface acoustic waves and elastic constants of InN epilayers determined by Brillouin scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Rioboo, R.J.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid (Spain); Cusco, R.; Domenech-Amador, N.; Artus, L. [Institut Jaume Almera, Consell Superior d' Investigacions Cientifiques (CSIC), Lluis Sole i Sabaris s.n., Barcelona, Catalonia (Spain); Yamaguchi, T.; Nanishi, Y. [Faculty of Science and Engineering, Ritsumeikan University, Noji-Higashi, Kusatsu, Shiga (Japan)

    2012-06-15

    The surface acoustic wave velocity in InN has been experimentally determined by means of Brillouin scattering experiments on c - and m -face epilayers. From simulations based on the Green's function formalism we determine the shear elastic constants c{sub 66} and c{sub 44} and propose a complete set of elastic constants for wurtzite InN. The analysis of the sagittal and azimuthal dependence of the surface acoustic wave velocity indicates a slightly different elastic behavior of the m -face sample that basically affects the c{sub 44} elastic constant. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Competition between the modulation instability and stimulated Brillouin scattering in a broadband slow light device

    International Nuclear Information System (INIS)

    We observe competition between the modulation instability (MI) and stimulated Brillouin scattering (SBS) in a 9.2 GHz broadband SBS slow light device, in which a standard 20 km long single-mode LEAF fibre is used as the SBS medium. We find that MI is dominant and depletes most of the pump power when we use an intense pump beam at ∼ 1.55 µm, where the LEAF fibre is anomalously dispersive. The dominance of the MI in the LEAF-fibre-based system suppresses the SBS gain, degrading the SBS slow light delay and limiting the SBS gain-bandwidth to 125 dB GHz. In a dispersion-shifted highly nonlinear fibre, the SBS slow light delay is improved due to the suppression of the MI, resulting in a gain-bandwidth product of 344 dB GHz, limited by our available pump power of 0.82 W

  10. Trehalose Bioprotective Effects in Lysozyme Aqueous Solution Studied by Brillouin Scattering and Calorimetric Measurements

    Science.gov (United States)

    Sasanuma, Keita; Seshimo, Yuichi; Hashimoto, Eiji; Ike, Yuji; Kojima, Seiji

    2008-05-01

    The bioprotective effect of trehalose in lysozyme aqueous solutions has been investigated by Brillouin scattering and modulated-temperature differential scanning calorimetry (MDSC). MDSC experiments show that the isothermal kinetics of thermally irreversible denaturation can be described by the Arrhenius equation. By the addition of trehalose, the irreversible denaturation of lysozyme is suppressed, and its activation energy is half that of the denaturation without trehalose. The sound velocity of lysozyme-trehalose-water ternary solutions obviously depends on the trehalose concentration. With increasing trehalose concentration, the sound velocity becomes higher because the hydration of trehalose reduces the hydrogen bonds between water molecules. Moreover, hydration around lysozyme molecules increases the sound velocity further. Trehalose molecules tend to aggregate with lysozyme molecules at high trehalose concentrations. The bioprotective effect of trehalose probably originates from the mechanical suppression of conformational fluctuations of lysozyme molecules.

  11. 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

  12. Tailorable stimulated Brillouin scattering in nanoscale silicon waveguides.

    Science.gov (United States)

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

    2013-01-01

    Nanoscale modal confinement is known to radically enhance the effect of intrinsic Kerr and Raman nonlinearities within nanophotonic silicon waveguides. By contrast, stimulated Brillouin-scattering nonlinearities, which involve coherent coupling between guided photon and phonon modes, are stifled in conventional nanophotonics, preventing the realization of a host of Brillouin-based signal-processing technologies in silicon. Here we demonstrate stimulated Brillouin scattering in silicon waveguides, for the first time, through a new class of hybrid photonic-phononic waveguides. Tailorable travelling-wave forward-stimulated Brillouin scattering is realized-with over 1,000 times larger nonlinearity than reported in previous systems-yielding strong Brillouin coupling to phonons from 1 to 18 GHz. Experiments show that radiation pressures, produced by subwavelength modal confinement, yield enhancement of Brillouin nonlinearity beyond those of material nonlinearity alone. In addition, such enhanced and wideband coherent phonon emission paves the way towards the hybridization of silicon photonics, microelectromechanical systems and CMOS signal-processing technologies on chip. PMID:23739586

  13. 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.

  14. [A Brillouin Scattering Spectrum Feature Extraction Based on Flies Optimization Algorithm with Adaptive Mutation and Generalized Regression Neural Network].

    Science.gov (United States)

    Zhang, Yan-jun; Liu, Wen-zhe; Fu, Xing-hu; Bi, Wei-hong

    2015-10-01

    According to the high precision extracting characteristics of scattering spectrum in Brillouin optical time domain reflection optical fiber sensing system, this paper proposes a new algorithm based on flies optimization algorithm with adaptive mutation and generalized regression neural network. The method takes advantages of the generalized regression neural network which has the ability of the approximation ability, learning speed and generalization of the model. Moreover, by using the strong search ability of flies optimization algorithm with adaptive mutation, it can enhance the learning ability of the neural network. Thus the fitting degree of Brillouin scattering spectrum and the extraction accuracy of frequency shift is improved. Model of actual Brillouin spectrum are constructed by Gaussian white noise on theoretical spectrum, whose center frequency is 11.213 GHz and the linewidths are 40-50, 30-60 and 20-70 MHz, respectively. Comparing the algorithm with the Levenberg-Marquardt fitting method based on finite element analysis, hybrid algorithm particle swarm optimization, Levenberg-Marquardt and the least square method, the maximum frequency shift error of the new algorithm is 0.4 MHz, the fitting degree is 0.991 2 and the root mean square error is 0.024 1. The simulation results show that the proposed algorithm has good fitting degree and minimum absolute error. Therefore, the algorithm can be used on distributed optical fiber sensing system based on Brillouin optical time domain reflection, which can improve the fitting of Brillouin scattering spectrum and the precision of frequency shift extraction effectively. PMID:26904844

  15. 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)

  16. 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.

  17. 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.

  18. 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...

  19. 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

  20. 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

  1. 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.

  2. 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...

  3. Noise sources and competition between stimulated Brillouin and Raman scattering: A one-dimensional steady-state approach

    International Nuclear Information System (INIS)

    A 1D steady-state model is developed to deal with stimulated scattering processes. The volume and boundary noise sources for scattered light are discussed in detail. Our results indicate that the boundary noise sources may play a significant role in estimating the reflectivity of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). With the capability of our model to deal with broadband scattered light, we find that pump depletion could be the main reason to the anti-correlation between SBS and SRS versus electron density observed in experiments. A simple method is proposed to phenomenologically include the effect of nonlinear saturation mechanisms in our model and reasonable results are obtained

  4. Nonlinear stimulated Brillouin scattering based photonic signal processors

    Energy Technology Data Exchange (ETDEWEB)

    Minasian, Robert A. [School of Electrical and Information Engineering, Institute of Photonics and Optical Science, University of Sydney, NSW, Sydney, 2006 (Australia)

    2014-10-06

    Recent new methods in photonic signal processing based on stimulated Brillouin scattering, that enable the realization of photonic mixers with high conversion efficiency, ultra-wide continuously tunable high-resolution microwave photonic filters and programmable switchable microwave photonic tunable filters, are presented. These processors provide new capabilities for the realisation of high-performance and high-resolution signal processing.

  5. Nonlinear stimulated Brillouin scattering based photonic signal processors

    International Nuclear Information System (INIS)

    Recent new methods in photonic signal processing based on stimulated Brillouin scattering, that enable the realization of photonic mixers with high conversion efficiency, ultra-wide continuously tunable high-resolution microwave photonic filters and programmable switchable microwave photonic tunable filters, are presented. These processors provide new capabilities for the realisation of high-performance and high-resolution signal processing

  6. 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.

  7. 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...

  8. 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.

  9. 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

  10. Distributed sensing employing stimulated Brillouin scattering in optical fibers

    OpenAIRE

    Antman, Yair; Thévenaz, Luc; Zadok, Avinoam

    2012-01-01

    Disclosed are methods and devices for distributed sensing of a measurable parameter employing stimulated Brillouin scattering in an optical fiber. A frequency-modulated or phase-modulated light wave is transmitted into the optical fiber. A scattered light wave in the optical fiber is monitored for sensing a measurable parameter. In some embodiments, the calculating step may include calculating a distance of a sensed location along the optical fiber using the monitored time of arrival.

  11. 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...

  12. 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

  13. Recent Progress in Brillouin Scattering Based Fiber Sensors

    Directory of Open Access Journals (Sweden)

    Liang Chen

    2011-04-01

    Full Text Available Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave, and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave, the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, and railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures.

  14. 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.

  15. 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...

  16. 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...

  17. Study of low-frequency dynamics of short peptides by Brillouin light scattering and Monte-Carlo global energy minimization

    International Nuclear Information System (INIS)

    Brillouin light scattering studies of the behavior of hypersound velocity in solutions of short peptides Asp-Ser, Glu-Asp-Arg, Ala-Glu-Asp-Leu with widely varying concentrations at temperatures ranging from 295 to 360K are presented. As shown by analysis of experimental data and molecular simulation, the dipeptide Asp-Ser is characterized by formation of dimers which decompose at high temperatures. High-concentration solutions of tri- and tetrapeptides form aggregates at high temperatures which are preserved on cooling

  18. Brillouin light scattering from surface acoustic waves in a subwavelength-diameter optical fibre.

    Science.gov (United States)

    Beugnot, Jean-Charles; Lebrun, Sylvie; Pauliat, Gilles; Maillotte, Hervé; Laude, Vincent; Sylvestre, Thibaut

    2014-01-01

    Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward-guided acoustic wave Brillouin scattering and backward-stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of Brillouin light scattering from surface acoustic waves. These Rayleigh-type surface waves travel the wire surface at a specific velocity of 3,400 m s(-1) and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics. PMID:25341638

  19. 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.

  20. 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.

  1. 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.)

  2. 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

  3. 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.

  4. 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.

  5. 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 ...

  6. 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.

  7. 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.

  8. 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

  9. ``Bloch wave'' modification of stimulated Raman by stimulated Brillouin scattering

    Science.gov (United States)

    Dodd, E. S.; Vu, H. X.; DuBois, D. F.; Bezzerides, B.

    2013-03-01

    Using the reduced-description particle-in-cell (RPIC) method, we study the coupling of backward stimulated Raman scattering (BSRS) and backward stimulated Brillouin scattering (BSBS) in regimes where the reflectivity involves the nonlinear behavior of particles trapped in the daughter plasma waves. The temporal envelope of a Langmuir wave (LW) obeys a Schrödinger equation where the potential is the periodic electron density fluctuation resulting from an ion-acoustic wave (IAW). The BSRS-driven LWs in this case have a Bloch wave structure and a modified dispersion due to the BSBS-driven spatially periodic IAW, which includes frequency band gaps at kLW˜kIAW/2˜k0 (kLW, kIAW, and k0 are the wave number of the LW, IAW, and incident pump electromagnetic wave, respectively). This band structure and the associated Bloch wave harmonic components are distinctly observed in RPIC calculations of the electron density fluctuation spectra and this structure may be observable in Thomson scatter. Bloch wave components grow up in the LW spectrum, and are not the result of isolated BSRS. Self-Thomson scattered light from these Bloch wave components can have forward scattering components. The distortion of the LW dispersion curve implies that the usual relationship connecting the frequency shift of the BSRS-scattered light and the density of origin of this light may become inaccurate. The modified LW frequency results in a time-dependent frequency shift that increases as the IAW grows, detunes the BSRS frequency matching condition, and reduces BSRS growth. A dependence of the BSRS reflectivity on the IAW Landau damping results because this damping determines the levels of IAWs. The time-dependent reflectivity in our simulations is characterized by bursts of sub-picosecond pulses of BSRS alternating with multi-ps pulses of BSBS, and BSRS is observed to decline precipitously as soon as SBS begins to grow from low levels. In strong BSBS regimes, the Bloch wave effects in BSRS are

  10. 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.

  11. 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

  12. Tailorable stimulated Brillouin scattering in nanoscale silicon waveguides

    OpenAIRE

    Shin, Heedeuk; Qiu, Wenjun; 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...

  13. 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

  14. Fermi states and anisotropy of Brillouin zone scattering in the decagonal Al-Ni-Co quasicrystal

    Science.gov (United States)

    Rogalev, V. A.; Gröning, O.; Widmer, R.; Dil, J. H.; Bisti, F.; Lev, L. L.; Schmitt, T.; Strocov, V. N.

    2015-10-01

    Quasicrystals (QCs) are intermetallic alloys that have excellent long-range order but lack translational symmetry in at least one dimension. The valence band electronic structure near the Fermi energy EF in such materials is of special interest since it has a direct relation to their unusual physical properties. However, the Fermi surface (FS) topology as well as the mechanism of QC structure stabilization are still under debate. Here we report the first observation of the three-dimensional FS and valence band dispersions near EF in decagonal Al70Ni20Co10 (d-AlNiCo) QCs using soft X-ray angle-resolved photoemission spectroscopy. We show that the FS, formed by dispersive Al sp-states, has a multicomponent character due to a large contribution from high-order bands. Moreover, we discover that the magnitude of the gap at the FS related to the interaction with Brillouin zone boundary (Hume-Rothery gap) critically differs for the periodic and quasiperiodic directions.

  15. 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.

  16. 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.

  17. On the dominant and subdominant behavior of stimulated Raman and Brillouin scattering driven by nonuniform laser beams

    International Nuclear Information System (INIS)

    In a number of experiments, stimulated Brillouin (SBS) or Raman backscattering (SRS) has been observed to be much more vigorous than the other although the expectations based on linear gain exponents are that they should both be reflecting large amounts of incident light. Multidimensional fluid simulations of the growth and saturation of these two instabilities driven by a nonuniform incident laser beam are presented. On the fast time scale, the nonlinear saturation occurs via an anomalous damping inspired by fundamental studies of Langmuir turbulence [D. F. DuBois et al., Bull. Am. Phys. Soc. 41, 1531 (1996)] and acoustic wave turbulence [B. I. Cohen et al., Phys. Plasmas 4, 956 (1997)]. Over a longer time scale, SRS and SBS are limited by quasilinear processes such as flows induced by the transfer of momentum from the light to the plasma and ion temperature increases caused by a loss of light energy in SBS. The simulations show a reduction of the SBS reflectivity under conditions of strong SRS reflectivity even if the laser energy is not depleted. The recent observations of decreasing SBS reflectivity with increasing plasma density [D. S. Montgomery, Phys. Plasmas 5, 1973 (1998)] are shown to be consistent with linear theory and nonlinear simulations of SBS provided the increasing levels of SRS are included. Because the reflectivity is produced by scattering in intense hotspots, where the local reflectivity can be very large, the SBS and SRS can be anticorrelated even when the total scattering is quite modest. copyright 1998 American Institute of Physics

  18. On the dominant and subdominant behavior of stimulated Raman and Brillouin scattering driven by nonuniform laser beams

    Science.gov (United States)

    Berger, R. L.; Still, C. H.; Williams, E. A.; Langdon, A. B.

    1998-12-01

    In a number of experiments, stimulated Brillouin (SBS) or Raman backscattering (SRS) has been observed to be much more vigorous than the other although the expectations based on linear gain exponents are that they should both be reflecting large amounts of incident light. Multidimensional fluid simulations of the growth and saturation of these two instabilities driven by a nonuniform incident laser beam are presented. On the fast time scale, the nonlinear saturation occurs via an anomalous damping inspired by fundamental studies of Langmuir turbulence [D. F. DuBois et al., Bull. Am. Phys. Soc. 41, 1531 (1996)] and acoustic wave turbulence [B. I. Cohen et al., Phys. Plasmas 4, 956 (1997)]. Over a longer time scale, SRS and SBS are limited by quasilinear processes such as flows induced by the transfer of momentum from the light to the plasma and ion temperature increases caused by a loss of light energy in SBS. The simulations show a reduction of the SBS reflectivity under conditions of strong SRS reflectivity even if the laser energy is not depleted. The recent observations of decreasing SBS reflectivity with increasing plasma density [D. S. Montgomery, Phys. Plasmas 5, 1973 (1998)] are shown to be consistent with linear theory and nonlinear simulations of SBS provided the increasing levels of SRS are included. Because the reflectivity is produced by scattering in intense hotspots, where the local reflectivity can be very large, the SBS and SRS can be anticorrelated even when the total scattering is quite modest.

  19. 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

  20. Protein dynamics in Brillouin light scattering: Termal denaturation of hen egg white lysozyme

    Science.gov (United States)

    Svanidze, A. V.; Lushnikov, S. G.; Kojima, S.

    2009-09-01

    Thermal denaturation of hen egg white lysozyme has been investigated by Brillouin light scattering in the temperature range from 297 to 350 K. Anomalies in the temperature dependences of velocity and damping of hypersound and also in the behavior of the intensity of Brillouin components for the lysozyme solution at thermal denaturation have been revealed. These anomalies are attributable to phase transformations of the protein in the high-temperature region. It has been shown that Brillouin light scattering is a suitable tool for studying the structural evolution of proteins.

  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 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.

  3. 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

  4. 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.

  5. Spectral shape of stimulated Brillouin scattering in crystals

    Science.gov (United States)

    Ohno, S.; Sonehara, T.; Tatsu, E.; Koreeda, A.; Saikan, S.

    2015-12-01

    We derived a formula to describe the stimulated Brillouin spectral shape in crystals for various temperatures ranging from room temperature to liquid-helium temperature. We modeled a sample as a one-dimensional system with a finite thickness in which the optically induced phonon propagates, partly interacting with the pump and probe laser beams. When the sample length is shorter than the propagation distance (i.e., the mean free path) of phonons, the spectral shape becomes multipeaked due to the multiple phonon reflections in the sample. Such a situation can be realized in a thin film or a bulk sample at low temperatures. We experimentally measured the Brillouin gain spectra with a multipeak structure in TeO2 and PbMoO4 crystals at low temperatures. We found that these spectra were reproduced by our formula for both the coaxial and off-axis phonon propagations with respect to the laser beams. It was revealed that our formula is very useful in estimating the phonon attenuation coefficient from the observed spectra, which gradually change from Lorentzian shape to a multipeak spectrum with decreasing temperature.

  6. Relaxation phenomena in supercooled liquid and glassy acetaminophen studied by dielectric, photon correlation and Brillouin light scattering spectroscopies

    Science.gov (United States)

    Kwon, Hyun-Joung; Kim, Tae Hyun; Ko, Jae-Hyeon; Hwang, Yoon-Hwae

    2013-01-01

    Relaxation phenomena and acoustic properties of acetaminophen in the glassy and supercooled liquid phase were studied by dielectric, photon correlation and Brillouin spectroscopies. Dielectric and photon correlation studies revealed the structural relaxation process while a new relaxation process was found by dielectric measurement in a much lower frequency range. The acoustic anomalies clearly indicated a glass transition at 293 K and some remnant localized motions in the glassy phase that contributed to the acoustic damping. Partial crystallization in the supercooled liquid phase was signified at temperatures above 318 K by drastic changes in the Brillouin spectrum and decrease in the dielectric strength.

  7. 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.

  8. 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

  9. 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.

  10. Elastic anomaly and order-disorder nature of multiferroic barium sodium niobate studied by broadband brillouin scattering

    International Nuclear Information System (INIS)

    The successive phase transitions of multiferroic barium sodium niobate, Ba2NaNb5O15 (BNN), were studied by Brillouin scattering. The LA, TA modes, and central peak were measured in a large temperature range from room temperature up to 750 °C. In the vicinity of a ferroelectric phase transition at about TC = 585 °C from the prototypic tetragonal 4/mmm to ferroelectric 4mm phases, elastic anomaly was observed for LA and TA modes. In addition, the order-disorder nature was observed by the temperature dependence of a central peak. For further cooling another elastic anomaly was also observed in the vicinity of a ferroelastic incommensurate phase transition at about TIC = 285 °C into orthorhombic 2mm phase with the appearance of incommensurate modulation. The large thermal hysteresis of elastic anomaly near TIC can be attributed the typical feature of the type III incommensurate phase transition predicted recently by Ishibashi and Iwata (2013 J. Phys. Soc. Jpn. 82 044703)

  11. Stimulated Brillouin scattering of laser in semiconductor plasma embedded with nano-sized grains

    International Nuclear Information System (INIS)

    A high power laser propagating through semiconductor plasma undergoes Stimulated Brillouin scattering (SBS) from the electrostrictively generated acoustic perturbations. We have considered that nano-sized grains (NSGs) ions are embedded in semiconductor plasma by means of ion implantation. The NSGs are bombarded by the surrounding plasma particles and collect electrons. By considering a negative charge on the NSGs, we present an analytically study on the effects of NSGs on threshold field for the onset of SBS and Brillouin gain of generated Brillouin scattered mode. It is found that as the charge on the NSGs builds up, the Brillouin gain is significantly raised and the threshold pump field for the onset of SBS process is lowered

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Wave front reversal during nonstationary stimulated Mandel'shtam-Brillouin scattering of focused beams

    Science.gov (United States)

    Betin, A. A.; Vasilev, A. F.; Kulagin, O. V.; Manishin, V. G.; Iashin, V. E.

    1985-09-01

    Consideration is given to the conditions for the existence and observation of wave front reversal in focused light beams due to nonstationary stimulated Mandel'shtam-Brillouin scattering. Experimental observations were carried out for light beams having small scale spatial inhomogeneities at a wavelength of 1.05 microns. The precision of the wave front reversal is determined, and the reflection coefficients of the Mandel'shtam-Brillouin scattering mirrors are measured with respect to quasi-homogeneous light beams under saturation conditions. The relative duration of the light pulses was t sub i/T2 = 0.15-1 (where T2 is the hypersound relaxation time). It is shown that the maximum duration of the pulses, which were reflected by a stimulated Mandel'shtam-Brillouin mirror, was limited by competing nonlinear breakdown and self-focusing processes. The accuracy of a correction for wave front reversal is also determined.

  20. 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)

  1. Observation of stimulated brillouin scattering in a microwave plasma interaction emperiment

    International Nuclear Information System (INIS)

    Stimulated Brillouin scattering of microwave radiation is investigated in an underdense laboratory plasma. The energy and momentum selection rules are seen to be satisfied for a variety of incident wavelengths (lambda0 = 3 approx. 10 cm) and ion species (He, Ne, Ar and Kr). The threshold power, growth rate and scattered power appear to be consistent with the finite interaction length theory. Saturation of the backscatter is observed and compared with existing theories

  2. Impact of nonlinear loss on Stimulated Brillouin Scattering

    CERN Document Server

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

    2015-01-01

    We study the impact of two-photon absorption (2PA) and fifth-order nonlinear loss such as 2PA-induced free-carrier absorption in semiconductors on the performance of Stimulated Brillouin Scattering devices. We formulate the equations of motion including effective loss coefficients, whose explicit expressions are provided for numerical evaluation in any waveguide geometry. We find that 2PA results in a monotonic, algebraic relationship between amplification, waveguide length and pump power, whereas fifth-order losses lead to a non-monotonic relationship. We define a figure of merit for materials and waveguide designs in the presence of fifth-order losses. From this, we determine the optimal waveguide length for the case of 2PA alone and upper bounds for the total Stokes amplification for the case of 2PA as well as fifth-order losses. The analysis is performed analytically using a small-signal approximation and is compared to numerical solutions of the full nonlinear modal equations.

  3. Fiber break location technique utilizing stimulated Brillouin scattering effects in optical fiber

    International Nuclear Information System (INIS)

    A new technique of fiber break detection system in optical communication networks is proposed and experimentally demonstrated in this paper. This technique is based-on continuous wave light source rather than pulsed source that is commonly deployed in existing techniques. The nonlinear effect of stimulated Brillouin scattering is manipulated to locate the fiber-break position in optical communication networks. This technique enables the utilization of a less-sensitive photodetector to detect the Brillouin Stokes line since its intensity increases with the fiber length in the detectable region. The fiber break location can be determined with accuracy of more than 98% for fiber length less than 50 km using this technique

  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. 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.

  6. 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.

  7. A new chopper spectrometer for neutron Brillouin scattering and low-angle neutron inelastic scattering: PHAROS (Phase 1)

    International Nuclear Information System (INIS)

    Phase I of PHAROS, the new chopper spectrometer at LANSCE, is described in detail. The main components are a water moderator, a 60-Hz double-bladed T-zero chopper, a 600Hz magnetic-bearing Fermi chopper, a 6m-long vacuum vessel with thin aluminium-alloy vacuum window and a 1.2m2 array of linear position-sensitive detectors

  8. 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...

  9. 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...

  10. 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.

  11. Variable delay using stationary and localized Brillouin dynamic gratings

    OpenAIRE

    Antman, Yair; Primerov, Nikolay; Sancho Dura, Juan; Thévenaz, Luc; Zadok, Avinoam

    2012-01-01

    Reflections from movable, dynamic acoustic gratings in polarization maintaining (PM) fibers are employed in the long variable delay of periodic, isolated pulses. The gratings are introduced by stimulated Brillouin scattering (SBS) interaction between two counter-propagating pump waves, which are spectrally detuned by the Brillouin frequency shift of the PM fiber and are both polarized along one of its principal axes. The gratings are interrogated by the reflections of read-out signals that ar...

  12. 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...

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

    International Nuclear Information System (INIS)

    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 N2 temperature (∼ 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 (H2S). As a result, three ratios of elastic constants to density were successfully determined at P = 3.70 GPa, T = 240 K: C11 /ρ = 16.4, C12 /ρ = 12.4, C44 /ρ = 7.57 x 106 m2 s-2. These values are almost the same as those obtained at room temperature

  14. Nonstationary Mandelstam-Brillouin stimulated scattering of focused light beams under conditions of saturation

    Science.gov (United States)

    Andreev, N. F.; Bespalov, V. I.; Dvoretskii, M. A.; Pasmanik, G. A.

    1983-10-01

    It is shown that with nonstationary Mandelstam-Brillouin stimulated scattering in SF6 (p = 16 atm), wave front reversal occurs over a wide range of changes in the energy of the laser radiation (0.3 to 3 J). The reversal has a large reflectivity (approximately 0.9-0.95) and high precision (approximately 0.95). It is found that the nonstationariness of the Mandelstam-Brillouin scattering leads to time variation in the spatial distribution of the hypersound and laser radiation intensities in the bulk of the nonlinear medium. With a sufficiently high energy of laser radiation, the characteristic region of its attenuation from the scattering by the hypersound into an oncoming Stokes wave is localized near the entrance to the nonlinear medium. As a result, the intensity of the radiation passing through the focal instability decreases sharply, and this aids in eliminating the optical breakdown.

  15. Improvement of thomson scattering diagnostics using stimulated-Brillouin-scattering-based phase conjugate mirrors

    International Nuclear Information System (INIS)

    In order to improve the measurement performance of incoherent Thomson scattering diagnostics, a high performance phase conjugate mirror based on stimulated Brillouin scattering (SBS-PCM) is applied to a Thomson scattering system for the first time in the JT-60U tokamak. We have demonstrated that a SBS-PCM which uses heavy-fluorocarbon liquid showed a high reflectivity of 95% at a high input-power of 145 W. Using the SBS-PCM, two newly developed methods were employed to increase the amount of scattered light. In the first method, we first developed a new optical design to provide a double-pass scattering scheme with the SBS-PCM. In this new optical design, a laser beam passing through the plasma is reflected by the SBS-PCM, and the reflected beam is returned via the same path by means of the phase conjugate effect, and is then passed through the plasma again, in order to increase the scattered light. A double-pass Thomson scattering scheme using the SBS-PCM was demonstrated in JT-60U ohmic plasma, resulting in an increase of the scattered light by a factor of 1.6, and the reduction of relative error by 2/3 for electron temperature measurement in contrast to single-pass scattering. A multi-pass Thomson scattering scheme is also proposed based on the results of double-pass scattering. It is estimated that multi-pass scattering allows the generation of several times the amount of scattered light, and the reduction of the relative error for electron temperature measurement by 37% in contrast to single-pass scattering. Regarding the second method, a high average-power of YAG laser system was developed by applying the SBS-PCM to a existent diagnostic laser. As a result, the average-power was increased by over 8 times in contrast to the average power of the original system, achieving up to 368 W (7.4 J x 50 Hz). (author)

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

    OpenAIRE

    Casas-Bedoya, Alvaro; Morrison, Blair; 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.

  17. 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.

  18. 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

  19. Stimulated Brillouin scattering for generating an acoustic wave in optical fibers

    Czech Academy of Sciences Publication Activity Database

    Holík, M.; Mikel, Břetislav; Urban, F.

    Bellingham : SPIE, 2012, 86971I:1-6. ISBN 978-0-8194-9481-8. [CPS 2012. Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics /18./. Ostravice (CZ), 03.09.2012-07.09.2012] R&D Projects: GA TA ČR TA01010995 Institutional support: RVO:68081731 Keywords : stimulated Brillouin scattering * acoustic wave * optical fiber Subject RIV: BH - Optics, Masers, Laser s

  20. Brillouin scattering from collective spin waves in magnetic superlattices (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Hillebrands, B.; Boufelfel, A.; Falco, C.M.; Baumgart, P.; Guentherodt, G.; Zirngiebl, E.; Thompson, J.D.

    1988-04-15

    We report on the observation and the analysis of collective magnetostatic spin-wave excitations in magnetic superlattices. The influence of interface anisotropies, which can become dominant for small modulation wavelengths, is discussed. For the system Fe/Pd we show that Brillouin spectroscopy experiments in combination with the measurement of the saturation magnetization by a SQUID magnetometer give evidence for a magnetic polarization of the Pd spacer layers, as well as for a small negative out-of-plane interface anisotropy constant of K/sub s/ = -0.15 erg/cm/sup 2/.

  1. Brillouin scattering from collective spin waves in magnetic superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Hillebrands, B.; Boufelfel, A.; Falco, C.M.; Baumgart, P.; Guentherodt, G.; Zirngiebl, E.; Thompson, J.D.

    1987-01-01

    We report on the observation and the analysis of collective magnetostatic spin-wave excitations in magnetic superlattices. The influence of interface anisotropies, which can become dominant for small modulation wavelengths, is discussed. For the system Fe/Pd we show that Brillouin spectroscopy experiments in combination with the measurement of the saturation magnetization by a SQUID magnetometer give evidence for a magnetic polarization of the Pd spacer layers, as well as for a small negative out-of-plane interface anisotropy constant of K/sub s/ = -0.15 erg/cm/sup 2/. 22 refs., 5 figs., 1 tab.

  2. 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.

  3. 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.

  4. Observation of the dynamic modes of a magnetic antivortex using Brillouin light scattering

    Science.gov (United States)

    Riley, Grant A.; Liu, H. J. Jason; Asmat-Uceda, Martin A.; Haldar, Arabinda; Buchanan, Kristen S.

    2015-08-01

    The dynamic behavior of magnetic antivortices stabilized in patterned pound-key-like microstructures was studied using microfocus Brillouin light scattering (micro-BLS) at frequencies above the gyrotropic mode (>1 GHz ). Micro-BLS spectra obtained as a function of the frequency of a driving microwave field show an intricate spectrum for the antivortex state for an in-plane driving field. Spatial mode profiles for the strongest antivortex resonance frequencies, obtained for samples in the antivortex as well as the single domain states, show that while the symmetry of one of the observed resonances is relatively insensitive to the spin configuration, the antivortex exhibits a unique mode profile for the other. A comparison with micromagnetic simulations shows that the frequency and symmetry of the latter are consistent with one of the antivortex azimuthal modes. Furthermore, the simulations show that this mode involves coupling between the antivortex spin excitations and propagating spin waves in the structure legs, which may be useful for high-wave-number spin-wave generation.

  5. “Bloch wave” modification of stimulated Raman by stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Using the reduced-description particle-in-cell (RPIC) method, we study the coupling of backward stimulated Raman scattering (BSRS) and backward stimulated Brillouin scattering (BSBS) in regimes where the reflectivity involves the nonlinear behavior of particles trapped in the daughter plasma waves. The temporal envelope of a Langmuir wave (LW) obeys a Schrödinger equation where the potential is the periodic electron density fluctuation resulting from an ion-acoustic wave (IAW). The BSRS-driven LWs in this case have a Bloch wave structure and a modified dispersion due to the BSBS-driven spatially periodic IAW, which includes frequency band gaps at kLW∼kIAW/2∼k0 (kLW, kIAW, and k0 are the wave number of the LW, IAW, and incident pump electromagnetic wave, respectively). This band structure and the associated Bloch wave harmonic components are distinctly observed in RPIC calculations of the electron density fluctuation spectra and this structure may be observable in Thomson scatter. Bloch wave components grow up in the LW spectrum, and are not the result of isolated BSRS. Self-Thomson scattered light from these Bloch wave components can have forward scattering components. The distortion of the LW dispersion curve implies that the usual relationship connecting the frequency shift of the BSRS-scattered light and the density of origin of this light may become inaccurate. The modified LW frequency results in a time-dependent frequency shift that increases as the IAW grows, detunes the BSRS frequency matching condition, and reduces BSRS growth. A dependence of the BSRS reflectivity on the IAW Landau damping results because this damping determines the levels of IAWs. The time-dependent reflectivity in our simulations is characterized by bursts of sub-picosecond pulses of BSRS alternating with multi-ps pulses of BSBS, and BSRS is observed to decline precipitously as soon as SBS begins to grow from low levels. In strong BSBS regimes, the Bloch wave effects in BSRS are

  6. Systematic Brillouin light scattering study of the elastic properties of porous silicon superlattices

    International Nuclear Information System (INIS)

    Brillouin light scattering spectroscopy was used to determine elastic properties of porous silicon films and superlattices. The film elastic properties were compared with previously published results and also used as input for an effective elastic medium model (M Grimsditch and F Nizzoli 1986, Phys. Rev. B 33 5891) to predict the elastic constants of porous silicon superlattices with constituent layers comprised of thin copies of the films. Values of superlattice elastic constants c33 and c44 obtained from the model show reasonably good agreement with those determined directly from superlattice Brillouin data while constants c11 and c13 show crude agreement. This partial agreement suggests that the model holds promise as a means for accurately predicting the elastic properties of p-Si SLs. The results of this study show that it is possible to tailor porous silicon superlattices for custom applications as well as further fundamental studies. (paper)

  7. 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.

  8. Detection of nonlinear picosecond acoustic pulses by time-resolved Brillouin scattering

    International Nuclear Information System (INIS)

    In time-resolved Brillouin scattering (also called picosecond ultrasonic interferometry), the time evolution of the spatial Fourier component of an optically excited acoustic strain distribution is monitored. The wave number is determined by the momentum conservation in photon-phonon interaction. For linear acoustic waves propagating in a homogeneous medium, the detected time-domain signal of the optical probe transient reflectivity shows a sinusoidal oscillation at a constant frequency known as the Brillouin frequency. This oscillation is a result of heterodyning the constant reflection from the sample surface with the Brillouin-scattered field. Here, we present an analytical theory for the nonlinear reshaping of a propagating, finite amplitude picosecond acoustic pulse, which results in a time-dependence of the observed frequency. In particular, we examine the conditions under which this information can be used to study the time-evolution of the weak-shock front speed. Depending on the initial strain pulse parameters and the time interval of its nonlinear transformation, our theory predicts the detected frequency to either be monotonically decreasing or oscillating in time. We support these theoretical predictions by comparison with available experimental data. In general, we find that picosecond ultrasonic interferometry of nonlinear acoustic pulses provides access to the nonlinear acoustic properties of a medium spanning most of the GHz frequency range

  9. 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.

  10. Multi-dimensional dynamics of stimulated Brillouin scattering in a laser speckle: Ion acoustic wave bowing, breakup, and laser-seeded two-ion-wave decay

    Science.gov (United States)

    Albright, B. J.; Yin, L.; Bowers, K. J.; Bergen, B.

    2016-03-01

    Two- and three-dimensional particle-in-cell simulations of stimulated Brillouin scattering (SBS) in laser speckle geometry have been analyzed to evaluate the relative importance of competing nonlinear processes in the evolution and saturation of SBS. It is found that ion-trapping-induced wavefront bowing and breakup of ion acoustic waves (IAW) and the associated side-loss of trapped ions dominate electron-trapping-induced IAW wavefront bowing and breakup, as well as the two-ion-wave decay instability over a range of Z Te/Ti conditions and incident laser intensities. In the simulations, the latter instability does not govern the nonlinear saturation of SBS; however, evidence of two-ion-wave decay is seen, appearing as a modulation of the ion acoustic wavefronts. This modulation is periodic in the laser polarization plane, anti-symmetric across the speckle axis, and of a wavenumber matching that of the incident laser pulse. A simple analytic model is provided for how spatial "imprinting" from a high frequency inhomogeneity (in this case, the density modulation from the laser) in an unstable system with continuum eigenmodes can selectively amplify modes with wavenumbers that match that of the inhomogeneity.

  11. 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.

  12. 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.

  13. Stimulated-Brillouin-scattering studies in low-density plasmas using microwave sources

    International Nuclear Information System (INIS)

    Observations of stimulated Brillouin scattering (SBS) in microwave interaction with a plasma, as verified by the satisfaction of the frequency and wavelength matching rules and growth rate, are presented. A small amount of chamber reflectivity causes ion fluctuations due to the standing-wave ponderomotive force, which then serve as an enhanced noise level for the initiation of the instability. Saturation of the backscatter is observed and compared with existing theories. The control of SBS using finite-bandwidth comb-type or random-noise-type pumps is also reported. (author)

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Observation of spin-wave dispersion in Nd-Fe-B magnets using neutron Brillouin scattering

    International Nuclear Information System (INIS)

    The low-energy spin-wave dispersion in polycrystalline Nd-Fe-B magnets was observed using neutron Brillouin scattering (NBS). Low-energy spin-wave excitations for the lowest acoustic spin-wave mode were clearly observed. From the spin-wave dispersion, we were able to determine the spin-wave stiffness constant Dsw (100.0 ± 4.9 meV.Å2) and the exchange stiffness constant A (6.6 ± 0.3 pJ/m)

  20. 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)

  1. 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.

  2. YAG laser performance improved by stimulated Brillouin scattering phase conjugation mirror in thomson scattering diagnostics at JT-60

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Hidetsugu; Nakatsuka, Masahiro [Osaka Univ., Institute of Laser Engineering, Suita, Osaka (Japan); Hatae, Takaki; Kitamura, Shigeru; Kashiwabara, Tsuneo [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2003-02-01

    An improvement of the output energy of a multistage YAG laser system by using a stimulated Brillouin scattering (SBS) phase conjugation mirror (PCM) was achieved. The phase conjugation of the optically nonlinear SBS process in a liquid material effectively compensated thermal degradation at an average/peak power amplifier, resulting in an average power increase from 1.5 J at 30 Hz repetition rate to 2.6 J at 50 Hz drive. The beam quality was also recovered without wave front deformation and depolarization resulting in a transfer-limited divergence with a good flat-top pattern in a near field. (author)

  3. YAG laser performance improved by stimulated Brillouin scattering phase conjugation mirror in thomson scattering diagnostics at JT-60

    International Nuclear Information System (INIS)

    An improvement of the output energy of a multistage YAG laser system by using a stimulated Brillouin scattering (SBS) phase conjugation mirror (PCM) was achieved. The phase conjugation of the optically nonlinear SBS process in a liquid material effectively compensated thermal degradation at an average/peak power amplifier, resulting in an average power increase from 1.5 J at 30 Hz repetition rate to 2.6 J at 50 Hz drive. The beam quality was also recovered without wave front deformation and depolarization resulting in a transfer-limited divergence with a good flat-top pattern in a near field. (author)

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Brillouin distributed sensing using localized and stationary dynamic gratings

    OpenAIRE

    Primerov, Nikolay; Antman, Yair; Sancho Dura, Juan; Zadok, Avinoam; Thévenaz, Luc

    2012-01-01

    In this work, we apply a recent technique for the generation of stimulated Brillouin scattering (SBS) dynamic gratings that are both localized and stationary to realize high-resolution distributed temperature sensing. The gratings generation method relies on the phase modulation of two pump waves by a common pseudo-random bit sequence (PRBS), with a symbol duration that is much shorter than the acoustic lifetime. This way the acoustic wave can efficiently build up in the medium at discrete lo...

  10. 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.

  11. 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.

  12. 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.

  13. Elastic properties of bismuth layer-structure perovskite single crystals studied by brillouin scattering

    International Nuclear Information System (INIS)

    Elastic properties of bismuth layered perovskite compounds, LaxBi4-xTi3O12 (LBT-x) and SrBi2Ta2O9 (SBT), were examined at room temperature by Brillouin scattering. Elastic stiffness coefficients, c33 and c44, defined in the pseudotetragonal symmetry, were obtained. The longitudinal sound velocities propagating along the c axis, were 3985 m/s and 3118 m/s for the pure bismuth titanate (BTO) and SBT, respectively. The sound velocity of SBT is very slow and is believed to be related with the weak interlayer bonding of this layer-structure compound. A simple linear chain model showed that the difference in the sound velocity between BTO and SBT is mainly due to the difference in the c axis lattice constant. The sound velocity of LBT-x increased slightly with the increase of x, while c33 seems to be insensitive to x

  14. Absolute instability of a laser-produced plasma during induced Mandelstam-Brillouin scattering

    International Nuclear Information System (INIS)

    The aim of investigation is to obtain the dependence of increments and frequencies of absolutely growing modes on the main plasma characteristics, laser radiation, as well as the calculation of saturation of the absolute instability of the forced Mandelstam-Brillouin scattering (FMBS) in a laser-produced plasma. A case is considered typical of a laser produced plasma when the primary role is played by density inhomogeneities and recession velocities. Explicit expressions for increments and frequencies of absolute FMBS instabilities in a hot plasma with an inhomogeneous density and recession velocity, are obtained. The absolute instability saturation due to the pumping wave depletion and generation of the second harmonics of ion-acoustic wave is considered

  15. 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.

  16. Beam combined laser fusion driver using stimulated Brillouin scattering phase conjugation mirrors

    International Nuclear Information System (INIS)

    The beam combination method using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCMs) is a promising technique for realizing the laser fusion driver with an ultrahigh energy/power laser system operating with a high repetition rate over 10 Hz. For realizing the beam combined laser system, it is necessary to lock/control the phases of SBS beams. In our previous papers, the new phase control technique using the self-generated density modulation was proposed, and its principle has been demonstrated experimentally. However, all the previous works were done without amplifiers. In this work, it has been demonstrated that the phase is stabilized with λ /51 fluctuation by standard deviation during 5,000 laser shots (500 sec.) in the two-beam combination system with amplifiers with 200 mJ total output energy and 10 Hz repletion rate. (author)

  17. 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.

  18. 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.

  19. Brillouin light scattering study of spin waves in NiFe/Co exchange spring bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Haldar, Arabinda; Banerjee, Chandrima; Laha, Pinaki; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700098 (India)

    2014-04-07

    Spin waves are investigated in Permalloy(Ni{sub 80}Fe{sub 20})/Cobalt(Co) exchange spring bilayer thin films using Brillouin light scattering (BLS) experiment. The magnetic hysteresis loops measured by magneto-optical Kerr effect show a monotonic decrease in coercivity of the bilayer films with increasing Py thickness. BLS study shows two distinct modes, which are modelled as Damon-Eshbach and perpendicular standing wave modes. Linewidths of the frequency peaks are found to increase significantly with decreasing Py layer thickness. Interfacial roughness causes to fluctuate exchange coupling at the nanoscale regimes and the effect is stronger for thinner Py films. A quantitative analysis of the magnon linewidths shows the presence of strong local exchange coupling field which is much larger compared to macroscopic exchange field.

  20. 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.

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

    International Nuclear Information System (INIS)

    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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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)

  15. 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

  16. 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.

  17. All-optical pulse compression of broadband microwave signal based on stimulated Brillouin scattering

    CERN Document Server

    Long, Xin; Chen, Jianping

    2015-01-01

    Pulse compression processing based on stimulated Brillouin scattering (SBS) in an optical fiber is theoretically and experimentally demonstrated. Broadband microwave signal is electro-optically modulated onto the pump lightwave that is launched into one end of the fiber. Acoustic wave in the fiber inherits the amplitude and phase information of the pump lightwave and thus the coupling between the acoustic wave and pump lightwave leads to the auto-correlated process of the pump lightwave as well as the modulated microwave signal. Derivation of the SBS coupling equations shows that the short-pulse probe lightwave amplified by the pump lightwave possesses the nature of auto-correlation formula. All-optical pulse compression of the broadband microwave signal is implemented after a subtraction between the detected probe pulse with and without SBS. A proof-of-concept experiment is carried out. The pulse compression of a linear frequency-modulated microwave signal with 1 GHz sweep range at the carrier frequency of 4...

  18. 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

  19. High frequency organ-pipe modes in amorphous boron carbide observed using surface Brillouin scattering

    International Nuclear Information System (INIS)

    Amorphous boron carbide films of 2 micron thickness were deposited at room temperature by a thermal deposition process on single-crystal silicon substrates. The elastic constants of an amorphous B4C film have been successfully measured by surface Brillouin scattering as a function of temperature, in the process, revealing a phase transition at about 350 deg.C. Quantized wave-vector components perpendicular to the film surface associated with organ-pipe modes occurring within the film were used in conjunction with elastodynamic Green's function calculations as well as independent measurement of longitudinal frequency from bulk excitations to extract the elastic constants

  20. 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)

  1. Brillouin distributed sensing using localized and stationary dynamic gratings

    Science.gov (United States)

    Primerov, Nikolay; Antman, Yair; Sancho, Juan; Zadok, Avi; Thevenaz, Luc

    2012-04-01

    In this work, we apply a recent technique for the generation of stimulated Brillouin scattering (SBS) dynamic gratings that are both localized and stationary to realize high-resolution distributed temperature sensing. The gratings generation method relies on the phase modulation of two pump waves by a common pseudo-random bit sequence (PRBS), with a symbol duration that is much shorter than the acoustic lifetime. This way the acoustic wave can efficiently build up in the medium at discrete locations only, where the phase difference between the two waves does not temporarily vary. The separation between neighboring correlation peaks can be made arbitrarily long. Using the proposed method, we experimentally demonstrate distributed temperature sensing with 5 cm resolution, based on modifications to both the local birefringence and the local Brillouin frequency shift in polarization maintaining fibers. The localization method does not require wideband detection and can generate the grating at any random position along the fiber, with complete flexibility. The phase-coding method is equally applicable to high-resolution SBS distributed sensing over standard fibers.

  2. 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.)

  3. 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

  4. 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)

  5. 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.

  6. Brillouin study of phonons, magnons and magnetoelastic coupling in the antiferromagnet KNiF3

    Science.gov (United States)

    Ganot, F.; Dugautier, S.; Moch, P.; Nouet, J.

    1981-03-01

    Brillouin scattering by magnons and acoustic phonons in KNiF3 has been studied as function of the temperature. At low temperature, we observe unusually large splittings of the phonon Brillouin lines, related to the multidomains structure of the samples. Using our determination of the anisotropy constant, K = 1.1×104 erg/cm3, we calculate from the splitting of the longitudinal [1, 1, 0] phonon a magnetoelastic coefficient ‖b2‖ = 3.3×107 erg/cm3. We also study the domains reorientation under an applied magnetic field.

  7. 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.

  8. 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.

  9. Variable delay using stationary and localized Brillouin dynamic gratings

    Science.gov (United States)

    Antman, Yair; Primerov, Nikolay; Sancho, Juan; Thévenaz, Luc; Zadok, Avi

    2012-03-01

    Reflections from movable, dynamic acoustic gratings in polarization maintaining (PM) fibers are employed in the long variable delay of periodic, isolated pulses. The gratings are introduced by stimulated Brillouin scattering (SBS) interaction between two counter-propagating pump waves, which are spectrally detuned by the Brillouin frequency shift of the PM fiber and are both polarized along one of its principal axes. The gratings are interrogated by the reflections of read-out signals that are polarized along the orthogonal principal axis. High-rate phase modulation of both pump waves by a pseudo-random binary sequence introduces dynamic gratings that are both localized and stationary, at specific locations in which the modulated pumps are correlated. The separation between adjacent correlation peaks can be made arbitrarily long. Long variable delays are readily obtained by scanning the grating along the fiber, via changing either the length or the rate of the modulation sequence. At the same time, the short length of the gratings, on the order of a cm, accommodates the delay of broadband pulses. The technique is therefore free of the delay-times-bandwidth product limitation that undermines the performance of SBS-based 'slow light' delay: we report the delay 1-ns long pulses by as much as 770 ns. In addition, the combined reflections from two dynamic gratings with a variable separation are used to implement radio-frequency photonic filters of tunable free spectral range. At the current stage, the technique is restricted by noise from residual scattering that takes place outside of the correlation peaks. Hence, it is thus far limited to the processing of repetitive signals, for which the noise may be effectively averaged out.

  10. Effects of material parameter on interaction length to occur optical phase conjugation via stimulated Brillouin scattering in semiconductors

    International Nuclear Information System (INIS)

    In the present formulation using hydrodynamic model and coupled mode scheme of plasmas the interaction length necessary to achieve optical phase conjugation is obtained from steady-state Brillouin gain coefficient for a semiconductor crystal. The analytical investigation of steady-state gain of stimulated Brillouin scattering (SBS) is made by assuming that the SBS is resulted from the nonlinear interaction of an intense electromagnetic wave with acoustic perturbation internally generated due to acousto-optic property of the semiconductor crystal. Numerical estimates confirm that when cyclotron frequency is tuned with pump frequency, interaction length is found to be nearly 104 m smaller than that obtained in absence of magnetic filed. Pump intensity and free carrier concentration both helpful in reducing the required interaction length. -- Highlights: ► OPC via SBS is obtained in doped semiconductors. ► Favourable interaction length to occur OPC is obtained. ► Magnetic field reduces interaction length. ► Minimum interaction length is obtained in dispersionless acoustic regime.

  11. 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)

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

    International Nuclear Information System (INIS)

    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)

  13. 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).

  14. 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.

  15. 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

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

    International Nuclear Information System (INIS)

    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

  17. 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.

  18. 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.

  19. High-resolution Brillouin fiber sensing using random phase coding of the pump and probe waves

    OpenAIRE

    Antman, Yair; Primerov, Nikolay; Thévenaz, Luc; Zadok, Avinoam

    2012-01-01

    Distributed temperature measurements with 1.2 cm resolution based on stimulated Brillouin scattering (SBS) in standard fibers are reported. High resolution is achieved by phase-coding both pump and probe waves with a high-rate, pseudo-random binary phase code. The SBS interaction is effectively confined to narrow correlation peaks. The separation between adjacent peaks, signifying the unambiguous measurement range, scales with the length of the modulation code and can therefore be made arbitr...

  20. 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...

  1. 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.

  2. The effect of pathological processes on absorption and scattering spectra of samples of bile and pancreatic juice

    Science.gov (United States)

    Giraev, K. M.; Ashurbekov, N. A.; Magomedov, M. A.; Murtazaeva, A. A.; Medzhidov, R. T.

    2015-07-01

    Spectra of optical transmission coefficients and optical reflectance for bile and pancreatic juice samples were measured experimentally for different forms of pathologies of the pancreas within the range of 250-2500 nm. The absorption and scattering spectra, as well as the spectrum of the anisotropy factor of scattering, were determined based on the results obtained using the reverse Monte Carlo method. The surface morphology for the corresponding samples of the biological media was studied employing electron microscopy. The dynamics of the optical properties of the biological media was determined depending on the stage of the pathology. It has been demonstrated that the results of the study presented are in a good agreement with pathophysiological data and could supplement and broaden the results of conventional methods for diagnostics of the pancreas.

  3. 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.

  4. 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.

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

    International Nuclear Information System (INIS)

    We report the observation of stimulated Brillouin scattering and lasing at 1550 nm in barium fluoride (BaF2) crystal. Brillouin lasing was achieved with ultra-high quality (Q) factor monolithic whispering gallery mode 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. BaF2 resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics

  6. 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.

  7. Analysis and simulation of photon scattering and neutron capture gamma spectra

    International Nuclear Information System (INIS)

    Within this thesis two twin experiments consisting of neutron capture and photon scattering on the neighbour isotopes 77Se/78Se and 195Pt/196Pt have been analysed to gain qualitative and quantitative information about the photon strength function and level density in the respective compound nuclei. For the analysis and simulation of both experimental types a new Monte Carlo simulation using a fast and efficient, extreme statistical treatment of radiative nuclear deexcitations, was developed. Furthermore the influence of fluctuations of transition widths on photon scattering were investigated and quantified. It could be shown that those lead to an enhancement of elastic scattering processes. The data analysis of both twin experiments reveals non-Lorentzian extra E1 photon strength below the neutron separation energy.

  8. Investigation of the Slow- and Fast-Light Effect on the Basis of Stimulated Brillouin Scattering for Application in Optical Communication and Information Systems.

    OpenAIRE

    Henker, Ronny

    2010-01-01

    In today's information age demand for ultra-fast information transfer with ultra-high bandwidths has reached extraordinary levels. Hence, the transmission in the future internet-backbone will be increasingly constrained in the network nodes. At the same time, the power consumption of the network systems will increase to unsustainable levels. To overcome these constraints power-ecient photonic networks which provide ultra-fast all-optical switching and routing are essential. Nowadays, optical ...

  9. Design and operation of high-energy and high-average-power diode-pumped single Nd:YAG amplifier with stimulated-Brillouin-scattering phase conjugate mirror

    International Nuclear Information System (INIS)

    We describe a compact laser-diode-pumped, phase conjugate Nd:YAG master oscillator power amplifier system with a reduced number of components in the single slab amplifier geometry. This system is readily suited for pumping a Ti:sapphire amplifier, making it possible to construct a compact, high-repetition-rate, terawatt-peak-power chirped-pulse amplification system. An average infrared power of 362 W at a repetition rate of 1 kHz in a 29 ns pulse has been produced with an optical-to-optical efficiency of 14%. With a KTiOPO4 frequency-doubling crystal, as average green output power of 132 W at a repetition rate of 1 kHz has also been generated when pumped at an input incident power of 222 W, corresponding to a second-harmonic energy conversion efficiency of 60%. The average power at both infrared and green wavelengths represents a record performance for a single-amplifier system. We discuss in detail the design, performance and operation of the system including output power, optical efficiency, beam quality and stability. (author)

  10. Time-Domain Techniques for Transient Scattering from Dielectric Bodies and Sea Surface Governed by Jonswap's Sea Spectra

    International Nuclear Information System (INIS)

    A time-domain surface integral equation (TDCFIE) approach is utilized to calculate the transient scattering from arbitrarily shaped, three-dimensional dielectric bodies. In conjunction with the marching-on-in-time (MOT) method, the TDCFIE-MOT method is used to derive explicit expressions for the present-time current as a function of the incident field. Sample results showing various geometries are presented and are compared with other numerical techniques. Finally, by an incident Gaussian plane tapered wave, transient scattering from the sea surface governed by Jonswap's sea spectra is computed. (fundamental areas of phenomenology (including applications))

  11. 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.

  12. SU-E-I-76: Matching Primary and Scattered X-Ray Spectra for Use in Calculating the Diagnostic Radiation Index of Protection

    Energy Technology Data Exchange (ETDEWEB)

    Pasciak, A [University of Tennessee Medical Center, Knoxville, TN (United States); Jones, A [MD Anderson Cancer Center, Houston, TX (United States); Wagner, L [UT Medical School, Houston, TX (United States)

    2014-06-01

    Purpose: Lightweight lead-free or lead-composite protective garments exploit k-edge interactions to attenuate scattered X-rays. Manufacturers specify the protective value of garments in terms of lead equivalence at a single kVp. This is inadequate, as the protection provided by such garments varies with radiation quality in different use conditions. We present a method for matching scattered X-ray spectra to primary X-ray spectra. The resulting primary spectra can be used to measure penetration through protective garments, and such measurements can be weighted and summed to determine a Diagnostic Radiation Index for Protection (DRIP). Methods: Scattered X-ray spectra from fluoroscopic procedures were modeled using Monte Carlo techniques in MCNP-X 2.7. Data on imaging geometry, operator position, patient size, and primary beam spectra were gathered from clinical fluoroscopy procedures. These data were used to generate scattered X-ray spectra resulting from procedural conditions. Technical factors, including kV and added filtration, that yielded primary X-ray spectra that optimally matched the generated scattered X-ray spectra were identified through numerical optimization using a sequential quadratic programming (SQP) algorithm. Results: The primary spectra generated with shape functions matched the relative flux in each bin of the scattered spectra within 5%, and half and quarter-value layers matched within 0.1%. The DRIP for protective garments can be determined by measuring the penetration through protective garments using the matched primary spectra, then calculating a weighted average according to the expected clinical use of the garment. The matched primary spectra are specified in terms of first and second half-value layers in aluminum and acrylic. Conclusion: Lead equivalence is inadequate for completely specifying the protective value of garments. Measuring penetration through a garment using full scatter conditions is very difficult. The primary spectra

  13. 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.

  14. 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

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

    OpenAIRE

    Lin, Guoping; Diallo, Souleymane; 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 gen...

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

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, K.S. [Univ. of California, Davis, CA (US)

    1993-02-11

    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. 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

  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. 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.

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. 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

  5. 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%.

  6. 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

  7. 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.

  8. Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the Hα line profiles and Thomson scattering spectra

    International Nuclear Information System (INIS)

    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 Hα, 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 Hα 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Brillouin optical correlation domain analysis with 4 millimeter resolution based on amplified spontaneous emission.

    Science.gov (United States)

    Cohen, Raphael; London, Yosef; Antman, Yair; Zadok, Avi

    2014-05-19

    A new technique for Brillouin scattering-based, distributed fiber-optic measurements of temperature and strain is proposed, analyzed, simulated, and demonstrated. Broadband Brillouin pump and signal waves are drawn from the filtered amplified spontaneous emission of an erbium-doped fiber amplifier, providing high spatial resolution. The reconstruction of the position-dependent Brillouin gain spectra along 5 cm of a silica single-mode fiber under test, with a spatial resolution of 4 mm, is experimentally demonstrated using a 25 GHz-wide amplified spontaneous emission source. A 4 mm-long localized hot spot is identified by the measurements. The uncertainty in the reconstruction of the local Brillouin frequency shift is ± 1.5 MHz. The single correlation peak between the pump and signal is scanned along a fiber under test using a mechanical variable delay line. The analysis of the expected spatial resolution and the measurement signal-to-noise ratio is provided. The measurement principle is supported by numerical simulations of the stimulated acoustic field as a function of position and time. Unlike most other Brillouin optical correlation domain analysis configurations, the proposed scheme is not restricted by the bandwidth of available electro-optic modulators, microwave synthesizers, or pattern generators. Resolution is scalable to less than one millimeter in highly nonlinear media. PMID:24921326

  15. Toward a new lower limit for the minimum scattering vector on the very small angle neutron scattering spectrometer at Laboratoire Leon Brillouin

    Energy Technology Data Exchange (ETDEWEB)

    Brulet, A.; Thevenot, V.; Lairez, D.; Desert, S. [CEA Saclay, CEA-CNRS, UMR12, Lab Leon Brillouin, F-91191 Gif Sur Yvette (France); Lecommandoux, S.; Agut, W. [Univ Bordeaux 1, ENSCPB CNRS, Lab Chim Polymeres Organ, F-33607 Pessac (France); Armes, S.P.; Du, J. [Univ Sheffield, Dept Chem, Sheffield S3 7HF (United Kingdom)

    2008-07-01

    The main characteristics of the very small angle neutron scattering spectrometer (VSANS) under construction at the Laboratoire Leon Brillouin are a multibeam pinhole collimator converging onto an image plate detector. By combining tiny collimation (diaphragms of around 1 or 2 mm in diameter) with the small pixel size of the detector (0.15 * 0.15 mm), very high resolution measurements can be achieved. The resolution function of the instrument contains a contribution from gravity, which is reduced by the intermediate masks of the collimator. Owing to the relatively short length of the VSANS instrument (around 14 m), this effect remains weak, in good agreement with the predictions. With a prototype multibeam collimator, an incident wavelength of 0.9 nm and the detector located at 6 m from the sample, it is possible to access q values as low as 4 * 10{sup -3} nm{sup -1} with very high q resolution. Promising preliminary experiments with high q resolution are reported, which open up new fields to the SANS technique. (authors)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. Off-axis phonon and photon propagation in porous silicon superlattices studied by Brillouin spectroscopy and optical reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, L. C., E-mail: lcparsons@mun.ca; Andrews, G. T., E-mail: tandrews@mun.ca [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada)

    2014-07-21

    Brillouin light scattering experiments and optical reflectance measurements were performed on a pair of porous silicon-based optical Bragg mirrors which had constituent layer porosity ratios close to unity. For off-axis propagation, the phononic and photonic band structures of the samples were modeled as a series of intersecting linear dispersion curves. Zone-folding was observed for the longitudinal bulk acoustic phonon and the frequency of the probed zone-folded longitudinal phonon was shown to be dependent on the propagation direction as well as the folding order of the mode branch. There was no conclusive evidence of coupling between the transverse and the folded longitudinal modes. Two additional observed Brillouin peaks were attributed to the Rayleigh surface mode and a possible pseudo-surface mode. Both of these modes were dispersive, with the velocity increasing as the wavevector decreased.

  3. Evaluation of Compton attenuation and photoelectric absorption coefficients by convolution of scattering and primary functions and counts ratio on energy spectra

    International Nuclear Information System (INIS)

    Estimation of Compton attenuation and the photoelectric absorption coefficients were explored at various depths. A new method was proposed for estimating the depth based on the convolution of two exponential functions, namely convolution of scattering and primary functions (CSPF), which the convolved result will conform to the photopeak region of energy spectrum with the variable energy-window widths (EWWs) and a theory on the scattering cross-section. The triple energy-windows (TEW) and extended triple energy-windows scatter correction (ETEW) methods were used to estimate the scattered and primary photons according to the energy spectra at various depths due to a better performance than the other methods in nuclear medicine. For this purpose, the energy spectra were employed, and a distinct phantom along with a technetium-99 m source was simulated by Monte Carlo method. The simulated results indicate that the EWW, used to calculate the scattered and primary counts in terms of the integral operators on the functions, was proportional to the depth as an exponential function. The depth will be calculated by the combination of either TEW or ETEW and proposed method resulting in the distinct energy-window. The EWWs for primary photons were in good agreement with those of scattered photons at the same as depths. The average errors between these windows for both methods TEW, and ETEW were 7.25% and 6.03% at different depths, respectively. The EWW value for functions of scattered and primary photons was reduced by increasing the depth in the CSPF method. This coefficient may be an index for the scattering cross-section

  4. Quark combinatorics and hadron spectra in e+e- annihilation and in deep inelastic scattering

    International Nuclear Information System (INIS)

    The quark conbinatorics predictions are compared to the data on pion, kaon, rho-meson, and antiproton production in e+e- annihilation. This approach is shown to be successful in description of the spectrum of secondary hadrons (s/#betta#)(dσ/dxsub(E)) (e+e- → a hadron) in the 0.1 +e- annihilation. This testifies to the fact that in the processes considered in this work quark statistics can be successful even limiting itself to the simplest assumption of dominance of lower hadron multiplets

  5. Long Variable Delay and Distributed Sensing Using Stationary and Localized Brillouin Dynamic Gratings

    OpenAIRE

    Antman, Yair; Primerov, Nikolay; Sancho Dura, Juan; Thévenaz, Luc; Zadok, Avinoam

    2012-01-01

    Stationary and localized Brillouin dynamic gratings are generated using phase modulation of both pump waves by a pseudo-random bit sequence. The gratings are applied to long variable delay of pulses and to cm-level distributed sensing

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Simulation of simultaneously obtaining ocean temperature and salinity using dual-wavelength Brillouin lidar

    International Nuclear Information System (INIS)

    A method for simultaneously obtaining the ocean temperature and salinity based on dual-wavelength Brillouin lidar is proposed in this letter. On the basis of the relationships between the temperature and salinity and the Brillouin shifts, a retrieval model for retrieving the temperature and salinity is established. By using the retrieval model, the ocean temperature and salinity can be simultaneously obtained through the Brillouin shifts. Simulation based on dual-wavelength Brillouin lidar is also carried out for verification of the accuracy of the retrieval model. Results show that the errors of the retrieval model for temperature and salinity are ±0.27 °C and ±0.33‰. (letter)

  14. 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⊙.

  15. Spacing-adjustable and wavelength-tunable multiwavelength fibre laser with nonlinear Brillouin gain and birefringence fibre loop mirror

    International Nuclear Information System (INIS)

    This paper demonstrates a room-temperature multiwavelength fibre laser with spacing-adjustability and wavelength-tunability. The nonlinear gain of self-excited stimulated Brillouin scattering can suppress mode competition induced by homogeneous broadening of Erbium-doped fibre. With the use of a birefringence fibre loop filter, the wavelength spacing can be adjusted by changing the length of the used birefringence fibre, and the lasing wavelengths can be finely tuned through modifying the filtering profile of the birefringence filter. Multiwavelength output with spectral spacing as small as 0.076 nm and a wavelength number of more than 80 has been successfully produced. (classical areas of phenomenology)

  16. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Guoping, E-mail: guoping.lin@femto-st.fr; Diallo, Souleymane; Saleh, Khaldoun; Martinenghi, Romain; Beugnot, Jean-Charles; Sylvestre, Thibaut; Chembo, Yanne K. [Optics Department, FEMTO-ST Institute (CNRS UMR6174), 25030 Besançon (France)

    2014-12-08

    We report the observation of stimulated Brillouin scattering and lasing at 1550 nm in barium fluoride (BaF{sub 2}) crystal. Brillouin lasing was achieved with ultra-high quality (Q) factor monolithic whispering gallery mode 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{sub 2} resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

  18. Inclusive proton spectra and total reaction cross sections for proton-nucleus scattering at 800 MeV

    International Nuclear Information System (INIS)

    Current applications of multiple scattering theory to describe the elastic scattering of medium energy protons from nuclei have been shown to be quite successful in reproducing the experimental cross sections. These calculations use the impulse approximation, wherein the scattering from individual nucleons in the nucleus is described by the scattering amplitude for a free nucleon. Such an approximation restricts the inelastic channels to those initiated by nucleon-nucleon scattering. As a first step in determining the nature of p + nucleus scattering at 800 MeV, both total reaction cross sections and (p,p') inclusive cross sections were measured and compared to the free p + p cross sections for hydrogen, deuterium, calcium 40, carbon 12, and lead 208. It is concluded that as much as 85% of all reactions in a nucleus proceed from interactions with a single nucleon in the nucleus, and that the impulse approximation is a good starting point for a microscopic description of p + nucleus interactions at 800 MeV

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Effects of Ion-Ion Collisions and Inhomogeneity in Two-Dimensional Kinetic Ion Simulations of Stimulated Brillouin Backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B I; Divol, L; Langdon, A B; Williams, E A

    2005-10-17

    Two-dimensional simulations with the BZOHAR [B.I. Cohen, B.F. Lasinski, A.B. Langdon, and E.A. Williams, Phys. Plasmas 4, 956 (1997)] hybrid code (kinetic particle ions and Boltzmann fluid electrons) have been used to investigate the saturation of stimulated Brillouin backscatter (SBBS) instability including the effects of ion-ion collisions and inhomogeneity. Ion-ion collisions tend to increase ion-wave dissipation, which decreases the gain exponent for stimulated Brillouin backscattering; and the peak Brillouin backscatter reflectivities tend to decrease with increasing collisionality in the simulations. Two types of Langevin-operator, ion-ion collision models were implemented in the simulations. In both models used the collisions are functions of the local ion temperature and density, but the collisions have no velocity dependence in the first model. In the second model, the collisions are also functions of the energy of the ion that is being scattered so as to represent a Fokker-Planck collision operator. Collisions decorrelate the ions from the acoustic waves in SBS, which disrupts ion trapping in the acoustic wave. Nevertheless, ion trapping leading to a hot ion tail and two-dimensional physics that allows the SBS ion waves to nonlinearly scatter remain robust saturation mechanisms for SBBS in a high-gain limit over a range of ion collisionality. SBS backscatter in the presence of a spatially nonuniform plasma flow is also investigated. Simulations show that depending on the sign of the spatial gradient of the flow relative to the backscatter, ion trapping effects that produce a nonlinear frequency shift can enhance (auto-resonance) or decrease (anti-auto-resonance) reflectivities in agreement with theoretical arguments.

  4. High-resolution long-range distributed Brillouin analysis using dual-layer phase and amplitude coding.

    Science.gov (United States)

    London, Yosef; Antman, Yair; Cohen, Raphael; Kimelfeld, Naama; Levanon, Nadav; Zadok, Avi

    2014-11-01

    A new, hybrid time-domain and correlation-domain Brillouin analysis technique is proposed and demonstrated, providing a large number of high-resolution acquisition points. The method is based on dual-layer hierarchal encoding of both amplitude and phase. The pump and signal waves are co-modulated by a relatively short, high-rate binary phase sequence. The phase modulation introduces Brillouin interactions in a large number of discrete and localized correlation peaks along the fiber under test. In addition, the pump wave is also amplitude-modulated by a slower, carefully synthesized, long on-off-keying sequence. Brillouin interactions at the correlation peaks imprint weak replicas of the pump amplitude sequence on the intensity of the output signal wave. The Brillouin amplifications at individual correlation peaks are resolved by radar-like, matched-filter processing of the output signal, following a recently-proposed incoherent compression protocol. The method provides two significant advantages with respect to previous, pulse-gated correlation-domain analysis schemes, which involved a single pump pulse. First, compression of the extended pulse sequence enhances the measurement signal-to-noise ratio, which is equivalent to that of a large number of averages over repeating single-pulse acquisitions. The acquisition times are potentially much reduced, and the number of resolution points that may be practically interrogated increases accordingly. Second, the peak power level of the pump pulses may be lowered. Hence, the onset of phase pattern distortion due to self-phase modulation is deferred, and the measurement range can be increased. Using the proposed method, the acquisition of Brillouin gain spectra over a 2.2 km-long fiber with a spatial resolution of 2 cm is demonstrated experimentally. The entire set of 110,000 resolution points is interrogated using only 499 position scans per choice of frequency offset between pump and signal. A 5 cm-long hot-spot, located

  5. Effects of electric field on acoustic properties of 0.83Pb(Mg1/3Nb2/3) -0.17PbTiO3 single crystals studied by Brillouin light scattering

    Science.gov (United States)

    Kim, Tae Hyun; Ko, Jae-Hyeon; Kojima, Seiji

    2013-03-01

    Relaxor-based ferroelectric Pb[(Mg1/3Nb2/3)1-x Tix]O3 (PMN-xPT) single crystals have attracted great attention because of their exceptionally strong piezoelectric properties. This peculiar characteristic was attributed to the rotation of polarization directions and structural complexity. In this study, the phase transition behaviors of PMN-17PT single crystals have been investigated under an electric field applied along [001] by micro-Brillouin scattering. PMN-17PT single crystals were grown by the modified Bridgeman method. The two (001) surfaces were Au-coated to apply the electric field, and the coating was thin enough to allow the incident beam to transmit without much loss. The electric field of different values was applied to the sample along the [001] direction, and the Brillouin scattering spectrum was measured under both field-heating (FH) and field-cooling (FC) conditions. The electric field of 1kV/cm induced a new longitudinal acoustic (LA) mode component along with a broad Brillouin peak evolving continuously from the paraelectric phase during both FC and FH processes. This was attributed to the remnant polar nanoregions that were not aligned under the electric field due to quenched random fields. However, the splitting of the LA mode did not appear when the electric field was over 2kV/cm indicating a clear structural phase transition. This research was supported in part by the Marubun Research Promotion Foundation and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0010497).

  6. Measurement and Simulation of Spontaneous Raman Scattering Spectra in High-Pressure, Fuel-Rich H2-Air Flames

    Science.gov (United States)

    Kojima, Jun; Nguyen, Quang-Viet

    2003-01-01

    Rotational vibrational spontaneous Raman spectra (SRS) of H2, N2, and H2O have been measured in H2-air flames at pressures up to 30 atm as a first stem towards establishing a comprehensive Raman spectral database for temperatures and species in high-pressure combustion. A newly developed high-pressure burner facility provides steady, reproducible flames with a high degree of flow precision. We have obtained an initial set of measurements that indicate the spectra are of sufficient quality in terms of spectral resolution, wavelength coverage, and signal-to-noise ratio for use in future reference standards. The fully resolved Stokes and anti-Stokes shifted SRS spectra were collected in the visible wavelength range (400-700 nm) using pulse-stretched 532 nm excitation and a non-intensified CCD spectrograph with a high-speed shutter. Reasonable temperatures were determined via the intensity distribution of rotational H2 lines at stoichiometry and fuel-rich conditions. Theoretical Raman spectra of H2 were computed using a semi-classical harmonic-oscillator model with recent pressure broadening data and were compared with experimental results. The data and simulation indicated that high-J rotational lines of H2 might interfere with the N2 vibrational Q-branch lines, and this could lead to errors in N2-Raman thermometry based on the line-fitting method. From a comparison of N2 Q-branch spectra in lean H2 low-pressure (1.2 atm) and high-pressure (30 atm) flames, we found no significant line-narrowing or -broadening effects at the current spectrometer resolution of 0.04 nm.

  7. The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects

    OpenAIRE

    Lutz, D.; Maiolino, R.; Spoon, H. W. W.; Moorwood, A. F. M.

    2004-01-01

    We use mid-infrared spectral decomposition to separate the 6micron mid-infrared AGN continuum from the host emission in the ISO low resolution spectra of 71 active galaxies and compare the results to observed and intrinsic 2-10keV hard X-ray fluxes from the literature. We find a correlation between mid-infrared luminosity and absorption corrected hard X-ray luminosity, but the scatter is about an order of magnitude, significantly larger than previously found with smaller statistics. Main cont...

  8. Simulation of energy spectra of slow He{sup +} ions scattered from a copper surface

    Energy Technology Data Exchange (ETDEWEB)

    Khalal-Kouache, K., E-mail: kkouache@yahoo.fr [Universite des Sciences et de la Technologie Houari Boumediene (USTHB), Faculte de Physique, Laboratoire SNIRM, Bab-Ezzouar, 16111 Algiers (Algeria); Primetzhofer, D.; Bauer, P. [Institut fuer Experimentalphysik, Johannes Kepler Universitaet, Altenbergstr. 69, A-4040 Linz (Austria)

    2011-06-15

    Scattering of low energy (2 keV) He{sup +} ions from a polycrystalline copper surface is studied. Experimental Time-Of-Flight (TOF) spectra are presented for different values of the angle of incidence {alpha} and a fixed scattering angle {theta} = 129{sup o}. Using Monte Carlo simulation, based on the TRIM (TRansport of Ions in Matter) code, energy spectra are calculated and compared to experimental data. The influence of different combinations of interaction potential and inelastic energy loss on the spectrum shape and on the angular distribution of the scattering yield is considered in the simulation. Simulations show very good agreement with the experiment for all investigated geometries. An analysis of the experimental yield of scattered particles in different parts of the spectrum is performed to gain information on the relative contributions of surface single scattering and multiple scattering.

  9. Exploiting the self-similar nature of Raman and Brillouin amplification

    Science.gov (United States)

    Trines, R.; Alves, E. P.; Fonseca, R. A.; Silva, L. O.; Webb, E.; Fiuza, F.; Cairns, R. A.; Bingham, R.; Norreys, P.

    2015-11-01

    Raman and Brillouin amplification are two schemes for amplifying and compressing short laser pulses in plasma. Depending on the laser and plasma configurations, these schemes could potentially deliver the high-energy high-power pulses needed for inertial confinement fusion, especially fast-ignition fusion. Analytical self-similar models for both Raman and Brillouin amplification have already been derived, but the consequences of this self-similar behavior are little known and hardly ever put to good use. In this talk, we will give an overview of the self-similar laws that govern the evolution of the probe pulse in Raman and Brillouin amplification, and show how these laws can be exploited, in particular regarding the parameters of the initial probe pulse, to control the properties of the final amplified probe and improve the efficiency of the process.

  10. Fiber-Optic Interferometry Using Narrowband Light Source and Electrical Spectrum Analyzer: Influence on Brillouin Measurement

    CERN Document Server

    Mizuno, Yosuke; Nakamura, Kentaro

    2014-01-01

    We observe an interference pattern using a simple fiber-optic interferometer consisting of an electrical spectrum analyzer and a narrowband light source, which is commonly employed for observing the Brillouin gain spectrum. This interference pattern expands well beyond the frequency range corresponding to the Brillouin frequency shift in silica fibers (approximately 11 GHz at 1550 nm). Using both silica single-mode and polymer optical sensing fibers, we then experimentally prove that the distinctive noise in a self-heterodyne-based Brillouin measurement with an unoptimized polarization state originates from the interference between the reference light and the Fresnel-reflected light. This noise can be almost completely suppressed by employing a delay line that is longer than the coherence length of the light source and by artificially applying a high loss near the open end of the sensing fiber.

  11. 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)

  12. 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

  13. 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.

  14. 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.

  15. Peculiar effective elastic anisotropy of nanometric multilayers studied by surface Brillouin scattering

    Science.gov (United States)

    Faurie, D.; Djemia, P.; Castelnau, O.; Brenner, R.; Belliard, L.; Le Bourhis, E.; Goudeau, Ph; Renault, P.-O.

    2015-12-01

    We show in this paper by using a two-scale transition model that the elastic anisotropy of a thin film specimen can be tuned by appropriate stacking design. The anisotropic behaviour is illustrated for two monophase thin films, namely W which is perfectly elastically isotropic and Au which is strongly elastically anisotropic, and for a nanometric W/Au multilayers. The experimental measurements show that the model capture the elastic anisotropy rather well even for a nanometric multilayer stacking (period of 12 nm) and that the elastic anisotropy of W/Au multilayer is more pronounced than the ones of the two components for a fraction of 50%. This enhanced anisotropy is discussed in view of the multilayer microstructure.

  16. Measurement of spectra of (e,e') scattering on 9Be and 12C nuclei in inelastic region at Q22/c2

    International Nuclear Information System (INIS)

    The spectra of the (e,e')-scattering on 9Be and 12C nuclei in the region of quasielastic scattering and Δ33-resonance production at angles 16 and 18 deg and primary electron energies from 1.45 GeV to 2.13 GeV are measured. A model-independent account of radiative distortions at energies 1.93 and 2.13 GeV is made. A comparison with the nuclear shell model calculations is made. The experimental data are obtained at the Erevan electron synchrotron. The background conditions are improved and the energy coverage of the set-up is enlarged by the improvement of the extraction path and pulse hodoscope of the spectrometer. 13 refs.; 5 figs

  17. Comparison of hyperspectral measurements of the attenuation and scattering coefficients spectra with modeling results in the north-eastern Baltic Sea

    Science.gov (United States)

    Sipelgas, Liis; Raudsepp, Urmas

    2015-11-01

    The spectral variations in the attenuation and scattering coefficients measured with a hyperspectral ac-spectra (Wetlabs) instrument were analyzed from a dataset collected in the vicinity of commercial harbors on the Estonian coast of the Gulf of Finland, Baltic Sea. In total, the measured TSM concentration varied from 0.4 to 30 mg L-1 and the concentration of Chl a varied from values below the detection limit (0.05) to 23 mg m-3. The reliability of the power law describing the particle attenuation cp (λ) and scattering bp(λ) coefficients was evaluated by means of a determination coefficient (R2). The power law described the particle attenuation spectra with high accuracy (R2 > 0.67), giving the dataset an average cp (λ) slope of 1.3. In the case of particle scattering coefficients, the power law did not represent the whole dataset. Depending on a particular spectrum, the R2 varied from 0 to 1.0 and the slope varied from 1.15 to -0.56. Decomposition of bp(λ) into dominant modes using principal component analyses resulted in the first principal mode accounting for the power law dependence of bp(λ), i.e. the "mineral-type" spectrum, and the second and third mode representing the characteristic bp(λ) of dominant algal particles, i.e. the "algae-type" spectrum. From our dataset we estimated that if Chl a concentration is above 10 mg m-3 or below 5 mg m-3 then most likely the "algae-type" or the "mineral-type" spectrum is dominant, respectively. There was strong linear relationship (R2 > 0.92) between TSM concentration and cp(555) and bp(555),irrespective of the dominant shape of the particle scattering spectra. The estimated TSM-specific attenuation and scattering coefficients at 555 nm were 0.8 m2 g-1 and 0.68 m2 g-1, respectively. Corresponding values for water samples with a dominant "mineral-type" spectrum were 0.85 m2 g-1 and 0.73 m2 g-1, respectively and for water samples with a dominant "algae-type" spectrum were 0.64 m2 g-1 and 0.52 m2 g-1, respectively.

  18. 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.

  19. 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.

  20. Model and conservation laws of stimulated Brillouin backscattered in an inhomogeneous flowing plasma

    International Nuclear Information System (INIS)

    The physics of momentum transfer from the laser field to the plasma ions is studied in the context of stimulated Brillouin scattering (SBS). In long-pulse regime (>1 ns), the momentum deposition leads to local flow inhomogeneities and density modifications in laser hot spots and changes significantly the physics of interaction. A set of equations that describe the self-consistent evolution of the laser field propagation, the backscattered transverse wave, the longitudinal ion acoustic wave (JAW) and the background plasma hydrodynamic is presented through a fluid description. In standard decay regime, a new three-dimensional paraxial equation describing the excitation of IAW in inhomogeneous flowing plasma is given in quasi-neutral limit. In particular, the rigorous and detailed computations of global momentum conservation involving different approximation levels in our fluid model have been carried out. Thus, the compatibility between the paraxial equation and the momentum conservation law has been checked. A multi-dimensional and parallel code Hera has been used to solve our full set of fluid equations in realistic large-size plasmas (hohlraums, gas jets). The numerical simulations based on such a model have shown to be very efficient in terms of computing time. (authors)

  1. 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.

  2. 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.

  3. 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.

  4. The phase transitions of ferroelectric Sr2Ta2O7 crystals by MDSC, Brillouin and dielectric spectroscopy

    Science.gov (United States)

    Hushur, A.; Shabbir, G.; Ko, J.-H.; Kojima, S.

    2004-04-01

    The structural phase transitions of Sr2Ta2O7 single crystals have been studied by the modulated temperature differential scanning calorimetry (MDSC), Brillouin scattering and dielectric spectroscopy. The specific heat (Cp) was measured over a wide temperature range from -150°C to 25°C and from 100°C to 210°C. The Cp curve showed an anomaly at To = 166.7°C, indicating the phase transition Cmcm rarr P21/m. The transition enthalpy DgrH, the transition entropy DgrS and specific heat jump DgrCp at To were estimated to be 0.465 J g-1, 1.01 mJ g-1 K-1 and 9.78 mJ g-1 K-1, respectively. The Cp anomaly associated with the ferroelectric phase transition at Tc = -107°C has not been detected. However, both Brillouin and dielectric data showed the anomalies corresponding to the ferroelectric phase transition from P21/m to P21.

  5. The phase transitions of ferroelectric Sr2Ta2O7 crystals by MDSC, Brillouin and dielectric spectroscopy

    International Nuclear Information System (INIS)

    The structural phase transitions of Sr2Ta2O7 single crystals have been studied by the modulated temperature differential scanning calorimetry (MDSC), Brillouin scattering and dielectric spectroscopy. The specific heat (Cp) was measured over a wide temperature range from -150 deg. C to 25 deg. C and from 100 deg. C to 210 deg. C. The Cp curve showed an anomaly at To 166.7 deg. C, indicating the phase transition Cmcm → P21/m. The transition enthalpy ΔH, the transition entropy ΔS and specific heat jump ΔCp at To were estimated to be 0.465 J g-1, 1.01 mJ g-1 K-1 and 9.78 mJ g-1 K-1, respectively. The Cp anomaly associated with the ferroelectric phase transition at Tc = -107 deg. C has not been detected. However, both Brillouin and dielectric data showed the anomalies corresponding to the ferroelectric phase transition from P21/m to P21

  6. 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-...

  7. 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. PMID:24663994

  8. 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.

  9. Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars

    Science.gov (United States)

    Zeng, Xiaodong; Bao, Xiaoyi; Chhoa, Chia Yee; Bremner, Theodore W.; Brown, Anthony W.; DeMerchant, Michael D.; Ferrier, Graham; Kalamkarov, Alexander L.; Georgiades, Anastasis V.

    2002-08-01

    The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is plus-or-minus15 mu][epsilon (mum/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and plus-or-minus5 mu][epsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are plus-or-minus7 and plus-or-minus15 mu][epsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is plus-or-minus20 mu][epsilon for the two-point loading case.

  10. 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.

  11. 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.

  12. 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.

  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. Multibeam seeded brillouin sidescatter in inertial confinement fusion experiments.

    Science.gov (United States)

    Turnbull, D; Michel, P; Ralph, J E; Divol, L; Ross, J S; Berzak Hopkins, L F; Kritcher, A L; Hinkel, D E; Moody, J D

    2015-03-27

    We present the first observations of multibeam weakly seeded Brillouin sidescatter in indirect-drive inertial confinement fusion (ICF) experiments. Two seeding mechanisms have been identified and quantified: specular reflections ("glint") from opposite hemisphere beams, and Brillouin backscatter from neighboring beams with a different angle of incidence. Seeded sidescatter can dominate the overall coupling losses, so understanding this process is crucial for proper accounting of energy deposition and drive symmetry. Glint-seeded scattered light could also be used to probe hydrodynamic conditions inside ICF targets. PMID:25860748

  15. 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

    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...

  16. 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.

  17. 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.

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

    International Nuclear Information System (INIS)

    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

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

    OpenAIRE

    Sancho Durá, Juan; Sales Maicas, Salvador; Primerov, N.; Chin, S; Antman, Y.; Zadok, A; Thevenaz, L.

    2012-01-01

    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 co...

  20. 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).

  1. Ambient dose equivalent and effective dose from scattered x-ray spectra in mammography for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations

    International Nuclear Information System (INIS)

    In this study, scattered x-ray distributions were produced by irradiating a tissue equivalent phantom under clinical mammographic conditions by using Mo/Mo, Mo/Rh and W/Rh anode/filter combinations, for 25 and 30 kV tube voltages. Energy spectra of the scattered x-rays have been measured with a Cd0.9Zn0.1Te (CZT) detector for scattering angles between 30 deg. and 165 deg. Measurement and correction processes have been evaluated through the comparison between the values of the half-value layer (HVL) and air kerma calculated from the corrected spectra and measured with an ionization chamber in a nonclinical x-ray system with a W/Mo anode/filter combination. The shape of the corrected x-ray spectra measured in the nonclinical system was also compared with those calculated using semi-empirical models published in the literature. Scattered x-ray spectra measured in the clinical x-ray system have been characterized through the calculation of HVL and mean photon energy. Values of the air kerma, ambient dose equivalent and effective dose have been evaluated through the corrected x-ray spectra. Mean conversion coefficients relating the air kerma to the ambient dose equivalent and to the effective dose from the scattered beams for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations were also evaluated. Results show that for the scattered radiation beams the ambient dose equivalent provides an overestimate of the effective dose by a factor of about 5 in the mammography energy range. These results can be used in the control of the dose limits around a clinical unit and in the calculation of more realistic protective shielding barriers in mammography

  2. Effects of interaction of folic acid with uranium (VI) and basic triphenylmethane dyes on resonance Rayleigh scattering spectra and their analytical applications

    International Nuclear Information System (INIS)

    In pH 4.2-4.8 HAc-NaAc buffer solution, folic acid (FA) could react with uranium (VI) to form a 2:1 anionic chelate which further reacted with some basic triphenylmethane dyes (BTPMD) such as Ethyl Violet (EV), Methyl Violet (MV) and Crystal Violet (CV) to form 1:2 ion-association complexes. As a result, not only the absorption spectra were changed, but also the intensities of resonance Rayleigh scattering (RRS) were enhanced greatly and the new RRS spectra were observed. The maximum RRS wavelengths were located at 328 nm for EV system, 325 nm for MV system and 328 nm for CV system. The fading degree (ΔA) and RRS intensities (ΔI) of three systems were different. Under given conditions, the ΔA and ΔI were all directly proportional to the concentration of FA. The linear ranges and the detection limits of RRS methods were 0.0039-5.0 μg mL-1 and 1.2 ng mL-1 for EV system, 0.0073-4.0 μg mL-1 and 2.2 ng mL-1 for MV system, 0.014-3.5 μg mL-1 and 4.7 ng mL-1 for CV system. The RRS methods exhibited higher sensitivity, so they are more suitable for the determination of trace FA. The optimum conditions, the influencing factors and the effects of coexisting substances on the reaction were investigated. The method can be applied to the determination of FA in serum and urine samples with satisfactory results. The structure of the ternary ion-association complex and the reaction mechanism were discussed in this work

  3. A new configuration of multi-wavelength Brillouin fiber laser

    International Nuclear Information System (INIS)

    A multi-wavelength laser is demonstrated using stimulated Brillouin scattering in a single-mode fiber with a feedback loop using two couplers and an optical circulator. This Brillouin fiber laser can operate at any wavelength depending on the Brillouin pump (BP) wavelength used. With a BP of 14 dBm, approximately 8 to 10 BFL lines are obtained in both forward and backward directions respectively with a line spacing of 0.16 nm. The use of the 99/1 coupler and 50/50 coupler gives the highest power and number of lines for the forward and backward outputs respectively. The maximum Stokes power obtained is approximately 8.0 dBm. The anti-Stokes lines are also obtained due to four wave mixing and bidirectional operation. The combination of forward and backward output can generate a larger number of lines with channel spacing of 0.08 nm

  4. 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.

  5. Moessbauer forward scattering spectra of ferromagnets in radio-frequency magnetic field

    International Nuclear Information System (INIS)

    The transmission of Moessbauer radiation through a thick ferromagnetic crystal, subjected to the radio-frequency (rf) magnetic field, is studied. A quantum-mechanical dynamical scattering theory is developed, taking into account both the periodical reversals of the magnetic field at the nuclei and their coherent vibrations. The Moessbauer forward scattering (FS) spectra of the weak ferromagnet FeBO3 exposed to the rf field are measured. It is discovered that the coherent gamma wave in the crystal, interacting with Moessbauer nuclei, absorbs or emits only couples of the rf photons. As a result, the FS spectra consist of equidistant lines spaced by twice the frequency of the rf field in contrast to the absorption spectra. Our experimental data and calculations well agree if we assume that the hyperfine field at the nuclei in FeBO3 periodically reverses and there are no coherent vibrations.

  6. Band structure of silicene on the zirconium diboride (0001) thin film surface - convergence of experiment and calculations in the one-Si-atom Brillouin zone

    OpenAIRE

    Lee, Chi-Cheng; Fleurence, Antoine; Yamada-Takamura, Yukiko; Ozaki, Taisuke; Friedlein, Rainer

    2014-01-01

    So far, it represents a challenging task to reproduce angle-resolved photoelectron (ARPES) spectra of epitaxial silicene by first-principles calculations. Here, we report on the resolution of the previously controversial issue related to the structural configuration of silicene on the ZrB$_2$(0001) surface and its band structure. In particular, by representing the band structure in a large Brillouin zone associated with a single Si atom, it is found that the imaginary part of the one-particle...

  7. Microwave Doppler spectra of sea return at small incidence angles: specular point scattering contribution

    International Nuclear Information System (INIS)

    It is well known that the sea return echo contains contributions from at least two scattering mechanisms. In addition to the resonant Bragg scattering, the specular point scattering plays an important role as the incidence angle becomes smaller (≤ 20 °). Here, in combination with the Kirchhoff integral equation of scattering field and the stationary phase approximation, analytical expressions for Doppler shift and spectral bandwidth of specular point scattering, which are insensitive to the polarization state, are derived theoretically. For comparison, the simulated results related to the two-scale method (TSM) and the method of moment (MOM) are also presented. It is found that the Doppler shift and the spectral bandwidth given by TSM are insufficient at small incidence angles. However, a comparison between the analytical results and the numerical simulations by MOM in the backscatter configuration shows that our proposed formulas are valid for the specular point scattering case. In this work, the dependences of the predicted results on incidence angle, radar frequency, and wind speed are also discussed. The obtained conclusions seem promising for a better understanding of the Doppler spectra of the specular point scattering fields from time-varying sea surfaces. (classical areas of phenomenology)

  8. 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.

  9. 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.

  10. 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; Korsholm, Søren Bang; Leipold, Frank; Meo, Fernando; Michelsen, Poul; Moseev, Dmitry; Rasmussen, Jesper; Salewski, Mirko; Schubert, M.; Stober, J.; Wagner, D. H.

    2014-01-01

    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...... temperature, rotation velocity, and plasma composition....

  11. Brillouin shifted third harmonic generation of a laser in a plasma

    International Nuclear Information System (INIS)

    The process of Brillouin shifted resonant third harmonic generation of an intense laser of finite spot size in a plasma is investigated. The laser of frequency ω0 and wave number k-vector0 excites an ion acoustic wave of frequency ω≅kcs and wave number k-vector≅2k-vector0, where cs is the ion acoustic speed, in the primary stimulated Brillouin scattering process. The laser also exerts a second harmonic ponderomotive force on electrons. This imparts them an oscillatory velocity v2ω0,2k0. This velocity beats with the electron density perturbation associated with the ion acoustic wave to produce a density perturbation at Brillouin shifted second harmonic. This perturbation couples with the oscillatory velocity vω0,k0 due to the laser to produce Brillouin shifted third harmonic current density and the radiation field. The phase matching is satisfied when plasma density is two third critical.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. Experimental program to elucidate and control stimulated Brillouin and Raman backscattering in long-scale plasmas

    International Nuclear Information System (INIS)

    Laser-plasma instability is a serious concern for indirect-drive inertial confinement fusion (ICF), where laser beams illuminate the interior of a cavity (called a hohlraum) to produce X-rays to drive the implosion of a fusion capsule. Stimulated Raman and Brillouin backscattering (SRS and SBS) could result in unacceptably high laser reflectivities. Unfortunately, it is impossible at present to fully simulate these processes realistically. Our experimental program aims to understand these instabilities by pursuing a dual strategy. (1) We use a gas-filled hohlraum design, which best approaches ignition-hohlraum conditions, on the Nova laser to identify important non linear trends. (2) We are shifting towards more fundamental experiments with a nearly diffraction-limited interaction laser beam illuminating extremely well characterized plasmas on the Trident laser facility at Los Alamos to probe the relevant fundamental processes. (author)

  1. Discontinuous Brillouin strain monitoring of small concrete bridges: comparison between near-to-surface and smart FRP fiber installation techniques

    Science.gov (United States)

    Bastianini, Filippo; Rizzo, Andrea; Galati, Nestore; Deza, Ursula; Nanni, Antonio

    2005-05-01

    Brillouin fiber optic sensing is a promising technology for Structural Health Monitoring (SHM) whose diffusion is however at present reduced by the unavailability of proper sensor products and established installation techniques specifically aimed at the building industry. Due to its intrinsic distributed sensing capability, Brillouin systems can individually measure the deformation of any single segment of considerable lengths of single-mode fiber. In addition, Brillouin retains all the other typical advantages of Fiber Optic Sensors (FOS), such as harsh environment durability and electro-magnetic interference rejection. These advantages, especially considering that the required sensors are really low cost, make the system particularly attractive for periodical ("discontinuous") strain monitoring of unattended infrastructures that might be exposed to ageing and vandalism damages. Despite the high equipment cost, the technique can become economically convenient when the same initial investment can be amortized over a number of applications that can be monitored periodically using the same device. This work presents a comparison between two different Brillouin sensor installation techniques: Near-to-Surface Fiber (NSF) embedding and smart-FRP sensor bonding. Both systems have been experimented in the field on small Reinforced Concrete (RC) bridges subject to a diagnostic load test. The obtained results clearly highlight the advantages of the smart-FRP system, in terms of performance enhancements, installation cost, and time reduction.

  2. MS-Xα calculation of the elastic electron scattering cross sections and x-ray absorption spectra of CX4 and SiX4 (X = H,F,Cl)

    International Nuclear Information System (INIS)

    Multiple scattering Xα bound state and continuum calculations are used to study low energy elastic electron scattering cross sections and pre-edge features in the x-ray absorption spectra (XAS) of (C,Si)X4, X = H,F,Cl. Maxima in the electron scattering cross section are predicted to occur at energies below 4 eV in the t2 channel for CF4, CCl4, SiH4, and SiCl4. These maxima can be assigned to final state orbitals which are bound in XAS and well localized in space and a quantitative correspondence of such scattering ''resonance'' energies and XAS energies may be obtained using the transition state approach. For CH4 and SiF4 even those bound state orbitals giving the greatest XAS intensity are very diffuse, being essentially of Rydberg character. Broad electron scattering maxima are found at energies above 4 eV in these molecules which cannot be directly associated with the bound state orbitals dominating the XAS. The results thus establish that low energy electron scattering resonances and pre-edge XAS are closely related only for orbitals bound and reasonably well localized in XAS. The MS-Xα results almost always reproduce experimental trends along the molecular series but quantitative discrepancies from experiment are sometimes substantial, particularly for the broad high energy scattering maxima in CH4. The narrow t2 resonance calculated for CF4 is found to vary greatly in position and intensity as the C--F distance is varied by small amounts but the stronger, broader t2 resonance in SiH4 is little affected by bond distance variation

  3. The phase transitions of ferroelectric Sr{sub 2}Ta{sub 2}O{sub 7} crystals by MDSC, Brillouin and dielectric spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hushur, A [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Shabbir, G [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Ko, J-H [Samsung Corning R and D Center, Paldal-gu, Sin-dong 472, 442-390, Suwon-si, Gyeonggi-do Province (Korea, Republic of); Kojima, S [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

    2004-04-07

    The structural phase transitions of Sr{sub 2}Ta{sub 2}O{sub 7} single crystals have been studied by the modulated temperature differential scanning calorimetry (MDSC), Brillouin scattering and dielectric spectroscopy. The specific heat (C{sub p}) was measured over a wide temperature range from -150 deg. C to 25 deg. C and from 100 deg. C to 210 deg. C. The C{sub p} curve showed an anomaly at T{sub o} 166.7 deg. C, indicating the phase transition Cmcm {yields} P2{sub 1}/m. The transition enthalpy {delta}H, the transition entropy {delta}S and specific heat jump {delta}C{sub p} at T{sub o} were estimated to be 0.465 J g{sup -1}, 1.01 mJ g{sup -1} K{sup -1} and 9.78 mJ g{sup -1} K{sup -1}, respectively. The C{sub p} anomaly associated with the ferroelectric phase transition at T{sub c} = -107 deg. C has not been detected. However, both Brillouin and dielectric data showed the anomalies corresponding to the ferroelectric phase transition from P2{sub 1}/m to P2{sub 1}.

  4. 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

  5. Optical cable fault locating using Brillouin optical time domain reflectometer and cable localized heating method

    International Nuclear Information System (INIS)

    A novel optical cable fault location method, which is based on Brillouin optical time domain reflectometer (BOTDR) and cable localized heating, is proposed and demonstrated. In the method, a BOTDR apparatus is used to measure the optical loss and strain distribution along the fiber in an optical cable, and a heating device is used to heat the cable at its certain local site. Actual experimental results make it clear that the proposed method works effectively without complicated calculation. By means of the new method, we have successfully located the optical cable fault in the 60 km optical fiber composite power cable from Shanghai to Shengshi, Zhejiang. A fault location accuracy of 1 meter was achieved. The fault location uncertainty of the new optical cable fault location method is at least one order of magnitude smaller than that of the traditional OTDR method

  6. Optical cable fault locating using Brillouin optical time domain reflectometer and cable localized heating method

    Science.gov (United States)

    Lu, Y. G.; Zhang, X. P.; Dong, Y. M.; Wang, F.; Liu, Y. H.

    2007-07-01

    A novel optical cable fault location method, which is based on Brillouin optical time domain reflectometer (BOTDR) and cable localized heating, is proposed and demonstrated. In the method, a BOTDR apparatus is used to measure the optical loss and strain distribution along the fiber in an optical cable, and a heating device is used to heat the cable at its certain local site. Actual experimental results make it clear that the proposed method works effectively without complicated calculation. By means of the new method, we have successfully located the optical cable fault in the 60 km optical fiber composite power cable from Shanghai to Shengshi, Zhejiang. A fault location accuracy of 1 meter was achieved. The fault location uncertainty of the new optical cable fault location method is at least one order of magnitude smaller than that of the traditional OTDR method.

  7. In-situ investigation of structure and magnetic properties of the epitaxial system Pd(111)Fe(110) on W(110) by means of Brillouin spectroscopy

    International Nuclear Information System (INIS)

    The in-situ observation of magnetostatic spin waves by Brillouin spectroscopy offers a versatile dynamical probe for the investigation of magnetic properties of thin films. The measured spin wave spectra of thin films contain a variety of information about their magnetic as well as structural properties. The frequency of a spin wave allows to determine, e.g., the g-factor, the magnetic anisotrophy constants and also the saturation magnetization. The spectral line shape allows conclusions about the film quality, i.e., steps or islands. Furthermore, the unidirectional propagation of the surface spin wave with respect to the magnetization allows to measure the coercitivity field of a film. The latter can be used as an additional characterization parameter of a magnetic film. Here the authors report on Brillouin spectroscopy investigations, which have been performed on the epitaxial system Pd(111)/Fe(110) on W(110). Additional detailed investigations of the epitaxy of this system, i.e., of the growth mode, structure and thermal stability have been carried out using LEED and Auger spectroscopy

  8. 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.

  9. 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.

  10. Tunable multiwavelength Brillouin-Erbium fiber laser with intra-cavity pre-amplified Brillouin pump

    International Nuclear Information System (INIS)

    We have demonstrated a new configuration of Brillouin-Erbium fiber laser, in which the Brillouin pump is pre-amplified within the laser cavity before entering the single-mode fiber. By using this simple scheme, a lower external Brillouin pump power is required to create the Brillouin gain and suppresses the laser cavity modes. The proposed laser structure exhibits a wide tuning range of 13 nm from 1597 nm to 1610 nm with 1480 nm pump power of 100 mW. The number of channels obtained within this wavelength range is 14 channels with 0.089 nm spacing

  11. 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.

  12. 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

  13. Measurement of Feynman-x spectra of photons and neutrons in the very forward direction in deep-inelastic scattering at HERA

    International Nuclear Information System (INIS)

    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 xF 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-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 2 2, of inelasticity 0.05 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. 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.

  15. 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

  16. 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.

  17. 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. PMID:26953777

  18. Measurement of Feynman-x spectra of photons and neutrons in the very forward direction in deep-inelastic scattering at HERA

    Czech Academy of Sciences Publication Activity Database

    Andreev, V.; Baghdasaryan, A.; Begzsuren, K.; Hladký, Jan; Reimer, Petr

    2014-01-01

    Roč. 74, č. 6 (2014), s. 1-30. ISSN 1434-6044 R&D Projects: GA MŠk LG14033 Institutional support: RVO:68378271 Keywords : H1 * DESY HERA * momentum transfer dependence * positron p * cross section * measurement * deep inelastic scattering * energy dependence * x-dependence Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.084, year: 2014

  19. 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

  20. Analysis of neutron spectra and fluxes obtained with cold and thermal moderators at IBR-2 reactor: experimental and computer modeling studies at small-angle scattering YuMO setup

    International Nuclear Information System (INIS)

    Results of experimental and computer modeling investigations of neutron spectra and fluxes obtained with cold and thermal moderators at the IBR-2 reactor (JINR, Dubna) are presented. The studies are done for small-angle neutron scattering (SANS) spectrometer YuMO (beamline number 4 of the IBR-2). The measurements of neutron spectra for two methane cold moderators are done for the standard configuration of the SANS instrument. The data from both moderators under different conditions of their operation are compared. The ratio of experimentally determined neutron fluxes of cold and thermal moderators at different wavelength is shown. Monte Carlo simulations are done to determine spectra for cold methane and thermal moderators. The results of the calculations of the ratio of neutron fluxes of cold and thermal moderators at different wavelength are demonstrated. In addition, the absorption of neutrons in the air gaps on the way from the moderator to the investigated sample is presented. SANS with the protein apoferritin was done in the case of cold methane as well as a thermal moderator and the data were compared. The perspectives for the use of the cold moderator for a SANS spectrometer at the IBR-2 are discussed. The advantages of the YuMO spectrometer with the thermal moderator with respect to the tested cold moderator are shown

  1. Function spectra and continuous G-spectra

    CERN Document Server

    Davis, Daniel

    2011-01-01

    Let G be a profinite group, {X_alpha}_alpha a cofiltered diagram of discrete G-spectra, and Z a spectrum with trivial G-action. We show how to define the homotopy fixed point spectrum F(Z, holim_alpha X_alpha)^{hG} and that when G has finite virtual cohomological dimension (vcd), it is equivalent to F(Z, holim_alpha (X_alpha)^{hG}). With these tools, we show that the K(n)-local Spanier-Whitehead dual is always a homotopy fixed point spectrum, a well-known Adams-type spectral sequence is actually a descent spectral sequence, and, for a sufficiently nice k-local profinite G-Galois extension E, with K a closed normal subgroup of G, the equivalence (E^{h_kK})^{h_kG/K} \\simeq E^{h_kG} (due to Behrens and the author), where (-)^{h_k(-)} denotes k-local homotopy fixed points, can be upgraded to an equivalence that just uses ordinary (non-local) homotopy fixed points, when G/K has finite vcd.

  2. 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.

  3. 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.

  4. 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.

  5. Microwave photonic filter using multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency shift

    International Nuclear Information System (INIS)

    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

  6. Regions for Brillouin seed pulse growth in relativistic laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, G.; Schluck, F.; Spatschek, K. H. [Institut fuer Theoretische Physik, Heinrich-Heine-Universitaet Duesseldorf, D-40225 Duesseldorf (Germany)

    2012-09-15

    Parametric plasma processes received renewed interest in the context of generating ultraintense and ultrashort laser pulses up to the exawatt-zetawatt regime. For Brillouin scattering and seed pulse amplification at high intensities, the strong coupling regime is of special interest. The intensity-driven low-frequency modes depend on the amplitudes of the laser fields. It is investigated here how these modes develop in the relativistic regime. Then, a unified treatment of Raman and Brillouin processes becomes necessary. Assuming circular polarization, it is shown that with increasing intensity an overlap of the originally different Raman, Brillouin, and modulational instability branches occurs. Numerical simulations with a linearized Maxwell-fluid code confirm the analytically predicted behavior.

  7. Regions for Brillouin seed pulse growth in relativistic laser-plasma interaction

    Science.gov (United States)

    Lehmann, G.; Schluck, F.; Spatschek, K. H.

    2012-09-01

    Parametric plasma processes received renewed interest in the context of generating ultraintense and ultrashort laser pulses up to the exawatt-zetawatt regime. For Brillouin scattering and seed pulse amplification at high intensities, the strong coupling regime is of special interest. The intensity-driven low-frequency modes depend on the amplitudes of the laser fields. It is investigated here how these modes develop in the relativistic regime. Then, a unified treatment of Raman and Brillouin processes becomes necessary. Assuming circular polarization, it is shown that with increasing intensity an overlap of the originally different Raman, Brillouin, and modulational instability branches occurs. Numerical simulations with a linearized Maxwell-fluid code confirm the analytically predicted behavior.

  8. Regions for Brillouin seed pulse growth in relativistic laser-plasma interaction

    International Nuclear Information System (INIS)

    Parametric plasma processes received renewed interest in the context of generating ultraintense and ultrashort laser pulses up to the exawatt-zetawatt regime. For Brillouin scattering and seed pulse amplification at high intensities, the strong coupling regime is of special interest. The intensity-driven low-frequency modes depend on the amplitudes of the laser fields. It is investigated here how these modes develop in the relativistic regime. Then, a unified treatment of Raman and Brillouin processes becomes necessary. Assuming circular polarization, it is shown that with increasing intensity an overlap of the originally different Raman, Brillouin, and modulational instability branches occurs. Numerical simulations with a linearized Maxwell-fluid code confirm the analytically predicted behavior.

  9. 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.

  10. 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)

  11. 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.

  12. 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.)

  13. Nonlinear Brillouin amplification of finite-duration seeds in the strong coupling regime

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, G.; Spatschek, K. H. [Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf, D–40225 Düsseldorf (Germany)

    2013-07-15

    Parametric plasma processes received renewed interest in the context of generating ultra-intense and ultra-short laser pulses up to the exawatt-zetawatt regime. Both Raman as well as Brillouin amplifications of seed pulses were proposed. Here, we investigate Brillouin processes in the one-dimensional (1D) backscattering geometry with the help of numerical simulations. For optimal seed amplification, Brillouin scattering is considered in the so called strong coupling (sc) regime. Special emphasis lies on the dependence of the amplification process on the finite duration of the initial seed pulses. First, the standard plane-wave instability predictions are generalized to pulse models, and the changes of initial seed pulse forms due to parametric instabilities are investigated. Three-wave-interaction results are compared to predictions by a new (kinetic) Vlasov code. The calculations are then extended to the nonlinear region with pump depletion. Generation of different seed layers is interpreted by self-similar solutions of the three-wave interaction model. Similar to Raman amplification, shadowing of the rear layers by the leading layers of the seed occurs. The shadowing is more pronounced for initially broad seed pulses. The effect is quantified for Brillouin amplification. Kinetic Vlasov simulations agree with the three-wave interaction predictions and thereby affirm the universal validity of self-similar layer formation during Brillouin seed amplification in the strong coupling regime.

  14. Neutrino scattering from hydrodynamic modes in hot and dense neutron matter

    OpenAIRE

    Shen, Gang; Reddy, Sanjay

    2013-01-01

    We calculate the scattering rate of low energy neutrinos in hot and dense neutron matter encountered in neutrons stars and supernova in the hydrodynamic regime. We find that the Brillouin peak, associated with the sound mode, and the Rayleigh peak, associated with the thermal diffusion mode, dominate the dynamic structure factor. Although the total scattering cross section is constrained by the compressibility sum rule, the differential cross-section calculated using the hydrodynamic response...

  15. Natural line shape reconstruction in the spectra of slow neutron quasielastic scattering by water

    International Nuclear Information System (INIS)

    The Bayes approach efficiency is analyzed while determining the natural line shape in the spectra of slow neutrons quasielastically scattered from water. The effect od apriori information on the solution character and nature is considered. The natural line shape is reconstructed for three cases of the effect of the resolution function on the experimental curve: strong - ΔEsub(resol),/ΔEsub(exp) = 0.67, moderate - (0.41), and weak - (0.11). The Lorentz and experimental curves are compared. In a different approach parameters of the corresponding lorentzian are detrmined. The both approaches yield practically coinciding curves, and it is concluded that the natural line shape for the case is rather reminiscent to the lorentzian. The Bayes method demostrates adequate stability to variations of apriori information

  16. Diffusive properties of water in Artemia cysts as determined from quasi-elastic neutron scattering spectra

    International Nuclear Information System (INIS)

    Results have been obtained on the quasi-elastic spectra of neutrons scattered from pure water, 20% agarose gel (hydration four grams H2O per gram of dry solid) and cysts of the brine shrimp Artemia for hydrations between 0.10 and 1.2 grams H2O 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 γ(Q2) 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 2> as determined from the Q-dependence of line areas were also obtained

  17. 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...

  18. 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.

  19. Resonance Rayleigh Scattering Spectra of an Ion-Association Complex of Naphthol Green B–Chitosan System and Its Application in the Highly Sensitive Determination of Chitosan

    Science.gov (United States)

    Zhang, Weiai; Ma, Caijuan; Su, Zhengquan; Bai, Yan

    2016-01-01

    This work describes a highly-sensitive and accurate approach for the determination of chitosan (CTS) using Naphthol Green B (NGB) as a probe in the Resonance Rayleigh scattering (RRS) method. The interaction between CTS and NGB leads to notable enhancement of RRS, and the enhancement is proportional to the concentration of CTS over a certain range. Under optimum conditions, the calibration curve of ΔI against CTS concentration was ΔI = 1860.5c + 86.125 (c, µg/mL), R2 = 0.9999, and the linear range and detection limit (DL) were 0.01–5.5 µg/mL and 8.87 ng/mL. Moreover, the effect of the molecular weight of CTS on the accurate quantification of CTS was studied. The experimental data were analyzed through linear regression analysis using SPSS20.0, and the molecular weight was found to have no statistical significance. This method has been applied to assay two CTS samples and obtained good recovery and reproducibility. PMID:27096866

  20. 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)

  1. 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.

  2. 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...

  3. 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

  4. 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].

  5. 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.

  6. 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

  7. 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.

  8. Analysis procedure for calculation of electron energy distribution functions from incoherent Thomson scattering spectra

    International Nuclear Information System (INIS)

    Incoherent Thomson scattering (ITS) provides a nonintrusive diagnostic for the determination of one-dimensional (1D) electron velocity distribution in plasmas. When the ITS spectrum is Gaussian its interpretation as a three-dimensional (3D) Maxwellian velocity distribution is straightforward. For more complex ITS line shapes derivation of the corresponding 3D velocity distribution and electron energy probability distribution function is more difficult. This article reviews current techniques and proposes an approach to making the transformation between a 1D velocity distribution and the corresponding 3D energy distribution. Previous approaches have either transformed the ITS spectra directly from a 1D distribution to a 3D or fitted two Gaussians assuming a Maxwellian or bi-Maxwellian distribution. Here, the measured ITS spectrum transformed into a 1D velocity distribution and the probability of finding a particle with speed within 0 and given value v is calculated. The differentiation of this probability function is shown to be the normalized electron velocity distribution function

  9. Interpretation of the burst spectra from X-ray burster MXB 1728-34 with allowance for Thomson scattering

    International Nuclear Information System (INIS)

    Spectral evolution is investigated and interpretations of the spectra are considered for a burst from the X-ray burster MXB 1728-34 detected by ASTRON. Interpretation of the burst spectra in terms of black.body radiation leads to improbably small neutron star (NS) mass M and radius R as well as distance D to the burster. Interpretation of the spectra around the burst maximum (first ≅4 s) in terms of radiation from an isothermal NS photosphere with dominating role of the Thomson scattering allows one to obtain reasonable constraints on M, R, and D (in particular, M=(1.4-2) M Sun, R=(6.5-12) km for D=6 kpk and helium photosphere). This interpretation leads to a conclusion that the photosphere expands up to several tens of kilometers in the burst maximum. The luminosity remains close to the Eddington limit during expansion and contraction; maxima of the observed flux corresponding to minima of the luminosity due to general relativity effects. The burst tail spectra are close to those of thermal bremstrahlung. Such spectra might originate in a corona around NS with mass ∼ 10 -16 MSun, radius ∼ 100 km and electron density ∼ 1019 cm-3, or in a hot layer with thickness ∼ 1-10 gxcm-2 on the photosphere

  10. Spatially resolved Brillouin spectroscopy to determine the rheological properties of the eye lens

    OpenAIRE

    Reiß, Stephan; Burau, Gerolf; Stachs, Oliver; Guthoff, Rudolf; Stolz, Heinrich

    2011-01-01

    Presbyopia is closely associated with the loss of accommodation, and hence with a decline in the viscoelastic properties of the human eye lens. In this article we describe a method for obtaining spatially resolved in vivo measurements of the rheological properties of the eye lens, based on the spectroscopic analysis of spontaneous Brillouin scattering using a virtually imaged phased array (VIPA). The multi-pass configuration enhances resolution to the extent that measurements are possible in ...

  11. 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.

  12. Correlation Functions and Power Spectra

    DEFF Research Database (Denmark)

    Larsen, Jan

    2006-01-01

    possible to define correlation functions and associated spectra for aperiodic, periodic and random signals although the interpretation is different. Moreover, we will discuss correlation functions when mixing these basic signal types. In addition, the note include several examples for the purpose of......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 and...... spectra for discrete-time and continuous-time (analog) signals are pretty similar. Consequently, we confine the discussion mainly to real discrete-time signals. The Appendix contains detailed definitions and properties of correlation functions and spectra for analog as well as discrete-time signals. It is...

  13. Correlation Functions and Power Spectra

    OpenAIRE

    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 and spectra for discrete-time and continuous-time (analog) signals are pretty similar. Consequently, we confine the discussion mainly to real discrete-time signals. The Appendix contains detailed defin...

  14. 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...

  15. 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

  16. 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

  17. Photon bremsstrahlung from quark jet via transverse and longitudinal scatterings: single versus multiple scatterings

    CERN Document Server

    Zhang, Le; Qin, Guang-You

    2016-01-01

    We study the production of jet-bremsstrahlung photons through the scattering with the constituents of a dense nuclear matter within the framework of deep-inelastic scattering off a large nucleus. Applying a gradient expansion up to the second order for the exchanged three-dimensional momentum between jet and medium, we derive the single photon bremsstrahlung spectrum with the inclusion of the contributions from the transverse broadening as well as the longitudinal drag and diffusion of the hard parton's momentum. We also compare the medium-induced photon radiation spectra for single scattering and from the resummation of multiple scatterings. It is found that the coupling between different scatterings can give additional contribution to medium-induced photon radiation, while for small momentum exchange, the leading contribution from the drag and diffusions to the photon emission spectra remain the same for single and multiple scatterings.

  18. 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.

  19. Studies of central interactions of Si ions at 14.5 x A GeV/c in Au and Cu

    International Nuclear Information System (INIS)

    Understanding the growth and saturation of parametric instabilities in laser-produced plasmas requires knowledge of the nonlinear properties of the instabilities and their interaction with each other. Nonlinear behavior of parametric instabilities, which are usually associated with unique optical features, have been evidenced in numerous experiments on a variety of laser facilities. We will discuss four examples of nonlinear behavior in laser-produced plasmas: nonlinear stimulated Brillouin scattering spectra, suppression of stimulated Raman scattering by stimulated Brillouin scattering, the parametric decay instability and the onset of turbulence, and the transition to ''bursting'' behavior of the two-plasmon decay instability. We also discuss experiments that demonstrate the nonlinear effects which occur as a consequence. 49 refs

  20. [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

  1. Hadron spectra and quarks

    International Nuclear Information System (INIS)

    The quark model began as little more than a quantum-number counting device. After a brief period during which quarks only played a symmetry role, serious interest in quark dynamics developed. The marriage of the principle of local gauge invariance and quarks has been astonishingly productive. Although many questions still need to be be answered, there is little doubt that the strong, weak and electroweak interactions of matter are described by gauge theories of interactions of the quarks. This review is focussed on the successes

  2. 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...... years there has been much interest in naturally occurring (as opposed to artificially stimulated) enhanced ion-acoustic spectra seen in the auroral zone and cusp/cleft region. A study of the plasma instability processes that lead to such spectra will help us to better understand auroral particle...... 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...

  3. 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.

  4. Vibronic spectra of Gd3+ in metaphosphate glasses: Comparison with Raman and infrared spectra

    International Nuclear Information System (INIS)

    Vibronic sidebands associated with the 6P/sub 7/2/→8S/sub 7/2/ transition of Gd3+-doped metaphosphate glasses are observed using line-narrowed fluorescence techniques. Glasses having metal cations of different mass and charge (La,Al,Mg,Ba) are examined. Vibronic spectra, which probe vibrations about the rare-earth element site, are compared with polarized Raman scattering data and the infrared dielectric constant obtained from near-normal reflectance measurements. Results indicate that in metaphosphate glasses vibronic selection rules are similar to HV (vertical height) Raman selection rules. The wavelengths and relative intensities of peaks in the high-frequency portion of the vibronic spectra change with respect to corresponding peaks in the Raman spectra when the mass and/or charge of Gd3+ differs significantly from that of the metal cation

  5. Neutrino scattering from hydrodynamic modes in hot and dense neutron matter

    CERN Document Server

    Shen, Gang

    2013-01-01

    We calculate the scattering rate of low energy neutrinos in hot and dense neutron matter encountered in neutrons stars and supernova in the hydrodynamic regime. We find that the Brillouin peak, associated with the sound mode, and the Rayleigh peak, associated with the thermal diffusion mode, dominate the dynamic structure factor. Although the total scattering cross section is constrained by the compressibility sum rule, the differential cross-section calculated using the hydrodynamic response function differs from results obtained in approximate treatments often used in astrophysics such as random phase approximations (RPA). We identified these differences and discuss its implications for neutrino transport in supernova.

  6. Deflection, spraying and induced scattering of intense laser beams in plasmas

    International Nuclear Information System (INIS)

    Investigations into laser beam spraying, deflection and induced scattering in plasmas are presented. Recent calculations and experiments on beam spraying due to filamentation are discussed. A simple model is presented for an enhanced beam deflection associated with nearly sonic plasma flow transverse to the beam. This model provides useful insights on the laser beam deflection, its scaling and the importance of self-consistent profile modifications. Finally, some discussion is given of recent experiments demonstrating the interplay between stimulated Raman and Brillouin scattering. (Author)

  7. Deflection, spraying, and induced scattering of intense laser beams in plasmas

    International Nuclear Information System (INIS)

    Investigations into laser beam spraying, deflection, and induced scattering in plasmas are presented. Recent calculations and experiments on beam spraying due to filamentation are discussed. A simple model is presented for an enhanced beam deflection associated with nearly sonic plasma flow transverse to the beam. This model provides useful insights on the laser beam deflection, its scaling and the importance of self-consistent profile modifications. Finally, some discussion is given of recent experiments demonstrating the interplay between stimulated.Raman and Brillouin scattering

  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. On the Relevance of Compton Scattering for the Soft X-ray Spectra of Hot DA White Dwarfs

    OpenAIRE

    Suleimanov, V.; Madej, J.; Drake, J. J.; Rauch, T.; Werner, K.

    2006-01-01

    We re-examine the effects of Compton scattering on the emergent spectra of hot DA white dwarfs in the soft X-ray range. Earlier studies have implied that sensitive X-ray observations at wavelengths $\\lambda < 50$ \\AA might be capable of probing the flux deficits predicted by the redistribution of electron-scattered X-ray photons toward longer wavelengths. We adopt two independent numerical approaches to the inclusion of Compton scattering in the computation of pure hydrogen atmospheres in hyd...

  11. 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...

  12. 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.

  13. 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.

  14. 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...

  15. 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

  16. 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...

  17. 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

  18. 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

  19. 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....

  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. Neutron spectra in the energy range from 10-8 to hundreds of MeV measurement in hard scattered radiation fields

    International Nuclear Information System (INIS)

    The technique of neutron spectra unfolding in wide energy range from 10-8 to hundreds of MeV on the base of multisphere Bonner's detector and plastic scintillator spectrometer ridings has been described. This technique is intended for neutron spectra measurements in fields of mixed scattered radiation behind accelerators shielding and neutron component of cosmic background. The expressions of neutron maximum equivalent and ambient doses in wide energy range and neutron fluences of energy above 20 MeV are presented. 13 refs.; 5 figs

  2. 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.

  3. Two plasmon decay and SRS [stimulated Raman scattering] instabilities in a 0.35 μm laser irradiated plasmas: Final technical report for the period 6 November 1984-31 July 1986

    International Nuclear Information System (INIS)

    Studies of stimulated Raman back and forward scattering and the generation of high energy electrons at 0.35 microns are presented. To isolate the various phenomena occurring at different densities, we attempted to control the plasma density by varying the thickness of the foil targets and also by using foam targets of variable average density. The frequency of the scattered light is used as a diagnostic to measure the plasma density. Time resolved and time integrated spectra for various plasma densities are discussed. Also, the measured energy and angular distribution of the high energy electrons from foil targets are presented. Two-plasmon decay is suggested as the probable mechanism generating the hot electrons. The backscattered light presents a broadband spectrum in the sub-half-harmonic region. This spectrum is limited by a sharp cut-off near 400 nm and by a spectral gap near the half-harmonic region. The half-harmonic spectrum is shown to be split into a red and a blue shifted peak. Effects of the self-generated magnetic fields and plasma temperature on Raman scattering and two-plasmon decay, respectively, are examined as possible mechanisms responsible for the splitting of the half-harmonic spectrum. Finally, a discussion of the effects of the coupling of Raman and Brillouin scattering on the Raman spectrum is presented with emphasis on the quarter critical region. This last mechanism is suggested to contribute to the splitting of the half-harmonic light

  4. 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.

  5. Operator functions and localization of spectra

    CERN Document Server

    Gil’, Michael I

    2003-01-01

    "Operator Functions and Localization of Spectra" is the first book that presents a systematic exposition of bounds for the spectra of various linear nonself-adjoint operators in a Hilbert space, having discrete and continuous spectra. In particular bounds for the spectra of integral, differential and integro-differential operators, as well as finite and infinite matrices are established. The volume also presents a systematic exposition of estimates for norms of operator-valued functions and their applications.

  6. 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.

  7. 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.

  8. Elastic properties, sp3 fraction, and Raman scattering in low and high pressure synthesized diamond-like boron rich carbides

    International Nuclear Information System (INIS)

    Dense BCx phases with high boron concentration are predicted to be metastable, superhard, and conductors or superconductors depending on boron concentration. However, up to this point, diamond-like boron rich carbides BCx (dl-BCx) phases have been thought obtainable only through high pressure and high temperature treatment, necessitating small specimen volume. Here, we use electron energy loss spectroscopy combined with transmission electron microscopy, Raman spectroscopy, surface Brillouin scattering, laser ultrasonics (LU) technique, and analysis of elastic properties to demonstrate that low pressure synthesis (chemical vapor deposition) of BCx phases may also lead to the creation of diamond-like boron rich carbides. The elastic properties of the dl-BCx phases depend on the carbon sp2 versus sp3 content, which decreases with increasing boron concentration, while the boron bonds determine the shape of the Raman spectra of the dl-BCx after high pressure-high temperature treatment. Using the estimation of the density value based on the sp3 fraction, the shear modulus μ of dl-BC4, containing 10% carbon atoms with sp3 bonds, and dl-B3C2, containing 38% carbon atoms with sp3 bonds, were found to be μ = 19.3 GPa and μ = 170 GPa, respectively. The presented experimental data also imply that boron atoms lead to a creation of sp3 bonds during the deposition processes.

  9. 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.

  10. Raman scattering and luminescence of high-Tc superconducting oxides

    International Nuclear Information System (INIS)

    Raman and luminescence spectra of high-Tc superconducting oxides are summarized, mainly YBa2Cu3O7-σ and partly La2-xBaxCuO4-σ. In raman spectra we succeeded to distinguish electron scattering to define the energy gap Δ in the superconducting state. The luminescence spectra are due to the emission of oxygen and interaction with conduction electrons. 70 refs.; 13 figs

  11. 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.

  12. 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)

  13. Effects of Fe-deficiency on magnetic properties and Brillouin function characteristics for NiCuZn ferrites

    International Nuclear Information System (INIS)

    The polycrystalline Ni0.56Cu0.10Zn0.34Fe2−xO4−3/2x (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 Bs and the coercivity Hc. More importantly, based on the Néel molecular field theory, for the spinel ferrites which do not only contain Fe3+ but also some other multiple magnetic ions (Ni2+ and Cu2+), the molecular field coefficients ωaa, ωbb and ωab=ωba are calculated by non-linear fitting method, and the Curie temperature Tc formula has been modified. With the increase of Fe-deficiency content, the values of ωaa and ωbb increase gradually, however, the value of ωab=ωba 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 (Fe3+, Ni2+, Cu2+) 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

  14. Inelastic neutron scattering spectra in f-electron compounds first-principles calculations

    CERN Document Server

    Divis, M

    2002-01-01

    A theoretical investigation of the rare earth (R sup 3 sup +) localized 4f electron states and band energy spectrum of RGa sub 2 intermetallics and RNi sub 2 B sub 2 C borocarbides is presented. To calculate the crystal field interaction, we used a parameter-free first-principles method based on density functional theory. It is shown that a reasonable and parameter-free theoretical description of the inelastic neutron scattering can be achieved, as is demonstrated for the particular cases DyGa sub 2 and NdNi sub 2 B sub 2 C. (orig.)

  15. All solid-state diode pumped Nd:YAG MOPA with stimulated Brillouin phase conjugate mirror

    OpenAIRE

    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 μs diode pulses in a stable oscillator. The oscillator is Q-switched and injection seeded with a commercial diode pumped single frequency CW Nd:YAG laser. The output consists of single-transverse, s...

  16. Measurement of charged particle spectra in deep-inelastic ep scattering at HERA

    International Nuclear Information System (INIS)

    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, 522, and small values of Bjorken-x, 10-4-2. The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity (η*) and transverse momentum (pT*) in the range 0*T*2. The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.

  17. Multiple-scattering approach to the x-ray-absorption spectra of perovskite-type compounds

    Science.gov (United States)

    Kitamura, Michihide; Muramatsu, Shinji; Sugiura, Chikara

    1988-04-01

    The metal K x-ray-absorption near-edge structure has been calculated for the first time from a multiple-scattering formalism for the perovskite-type compounds KMnF3, KFeF3, KCoF3, KNiF3, and KZnF3. The calculation includes the effects of a core hole and of Madelung corrections for crystal potentials. It is shown that the results including the lifetime-broadening effect are in good agreement with the experiment of Shulman et al.

  18. Long term structural health monitoring by Brillouin fibre-optic sensing: a real case

    International Nuclear Information System (INIS)

    We report the results of a long term structural health monitoring (SHM) test campaign performed on a concrete bridge. A one-year test campaign was performed by a portable prototype instrument based on stimulated Brillouin scattering in a single-mode optical fibre. The optical fibre sensor was attached along one arch of the bridge using two types of adhesive for comparison purposes. The attached fibre was able to provide the strain distribution along the structure during the one-year test campaign, with a spatial resolution of 1 m. A crack was revealed and correctly localized by the distributed sensor. (paper)

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  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. Raman spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane for combustion applications

    International Nuclear Information System (INIS)

    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. - Highlights: • Experimental Raman spectra of hydrocarbons in the 300–860 K temperature range. • Experimental Raman spectra of formaldehyde in the 400–860 K temperature range. • “Synthetic” spectra as sum of Gaussian curves to match experimental spectra. • Low resolution spectra typical of combustion application from “synthetic” spectra

  6. 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.

  7. Influence of multi-orbital hopping and anisotropy in intra and inter orbital Coulomb interactions on the electronic spectra in iron pnictide superconductors

    International Nuclear Information System (INIS)

    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

  8. 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

  9. Brillouin resonance broadening due to structural variations in nanoscale waveguides

    Science.gov (United States)

    Wolff, C.; Van Laer, R.; Steel, M. J.; Eggleton, B. J.; Poulton, C. G.

    2016-02-01

    We study the impact of structural variations (that is slowly varying geometry aberrations and internal strain fields) on the width and shape of the stimulated Brillouin scattering (SBS) resonance 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. Finally, we illustrate in a numerical example that in backward SBS and inter-mode forward SBS the existence of two broadening mechanisms with opposite sign also opens the possibility to compensate the effect of geometry-induced broadening. Our results can be transferred to other micro- and nano-structured waveguide geometries such as photonic crystal fibres.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Ultra-narrow linewidth single longitudinal mode Brillouin fiber ring laser using highly nonlinear fiber

    International Nuclear Information System (INIS)

    In this letter, we demonstrate a single longitudinal mode (SLM) Brillouin fiber laser by using highly nonlinear fiber (HNLF) as the nonlinear medium in which the stimulated Brillouin scattering effect takes place. The first Stokes line is generated at a threshold power of 18 dBm with a wavelength shift 0.08 nm from the Brillouin pump. The signal-to-noise ratio of the first Stokes line is measured to be ∼58 dB. To the best of the authors’ knowledge, this is the first report of a 0.7 kHz ultra-narrow linewidth of an SLM Brillouin fiber laser, using HNLF as the nonlinear medium, which features a simple cavity configuration. (letter)

  15. 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)

  16. Spin collective mode and quasiparticle contributions to STM spectra of d-wave superconductors with pinning

    Energy Technology Data Exchange (ETDEWEB)

    Polkovnikov, Anatoli; Sachdev, Subir; Vojta, Matthias

    2003-05-15

    We present additional details of the scanning tunneling microscopy spectra predicted by the model of pinning of dynamic spin collective modes in d-wave superconductor proposed by Polkovnikov et al. [Phys. Rev. B 65 (2002) 220509]. Along with modulations at the twice the wavevector of the spin collective mode, the local density of states (LDOS) displays features linked to the spectrum of the Bogoliubov quasiparticles. The former is expected to depend more strongly on an applied magnetic field or the doping concentration. The spin collective mode and the quasiparticles are distinct, co-existing, low energy excitations of the d-wave superconductor (strongly coupled only in some sectors of the Brillouin zone), and should not be viewed as mutually exclusive sources of LDOS modulation.

  17. Spin collective mode and quasiparticle contributions to STM spectra of d-wave superconductors with pinning

    International Nuclear Information System (INIS)

    We present additional details of the scanning tunneling microscopy spectra predicted by the model of pinning of dynamic spin collective modes in d-wave superconductor proposed by Polkovnikov et al. [Phys. Rev. B 65 (2002) 220509]. Along with modulations at the twice the wavevector of the spin collective mode, the local density of states (LDOS) displays features linked to the spectrum of the Bogoliubov quasiparticles. The former is expected to depend more strongly on an applied magnetic field or the doping concentration. The spin collective mode and the quasiparticles are distinct, co-existing, low energy excitations of the d-wave superconductor (strongly coupled only in some sectors of the Brillouin zone), and should not be viewed as mutually exclusive sources of LDOS modulation

  18. 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.

  19. Thomson scattering in dense plasmas with density and temperature gradients

    Science.gov (United States)

    Fortmann, C.; Thiele, R.; Fäustlin, R. R.; Bornath, Th.; Holst, B.; Kraeft, W.-D.; Schwarz, V.; Toleikis, S.; Tschentscher, Th.; Redmer, R.

    2009-09-01

    Collective X-ray Thomson scattering has become a versatile tool for the diagnostics of dense plasmas. Assuming homogeneous density and temperature throughout the target sample, these parameters can be determined directly from the plasmon dispersion and the ratio of plasmon amplitudes via detailed balance. In inhomogeneous media, the scattering signal is an average of the density and temperature dependent scattering cross-section weighted with the density and temperature profiles. We analyse Thomson scattering spectra in the XUV range from near solid density hydrogen targets generated by free electron laser radiation. The influence of plasma inhomogeneities on the scattering spectrum is investigated by comparing density and temperature averaged scattering signals to calculations assuming homogeneous targets. We find discrepancies larger than 10% between the mean electron density and the effective density as well as between the mean temperature and the effective temperature.

  20. Thomson scattering in dense plasmas with density and temperature gradients

    CERN Document Server

    Fortmann, C; Fäustlin, R R; Bornath, Th; Holst, B; Kraeft, W -D; Schwarz, V; Toleikis, S; Tschentscher, Th; Redmer, R

    2009-01-01

    Collective X-ray Thomson scattering has become a versatile tool for the diagnostics of dense plasmas. Assuming homogeneous density and temperature throughout the target sample, these parameters can be determined directly from the plasmon dispersion and the ratio of plasmon amplitudes via detailed balance. In inhomogeneous media, the scattering signal is an average of the density and temperature dependent scattering cross-section weighted with the density and temperature profiles. We analyse Thomson scattering spectra in the XUV range from near solid density hydrogen targets generated by free electron laser radiation.The influence of plasma inhomogeneities on the scattering spectrum is investigated by comparing density and temperature averaged scattering signals to calculations assuming homogeneous targets. We found discrepancies larger than 10% between the mean electron density and the effective density as well as between the mean temperature and the effective temperature.

  1. 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.

  2. Brillouin filtering of optical combs for narrow linewidth frequency synthesis

    Science.gov (United States)

    Galindo-Santos, Juan; Velasco, Aitor V.; Carrasco-Sanz, Ana; Corredera, Pedro

    2016-05-01

    We report a tunable monochromatic source generation scheme, based on Brillouin filtering of a self-referenced optical frequency comb. The system benefits from the high stability and mode linewidth of the frequency comb, significantly improving the performance of the original laser source used as Brillouin pump. A synthesized frequency with stability under 4×10-11 and a linewidth under 75 kHz was experimentally demonstrated for two separate pump lasers in the C-band. The proposed monochromatic source can be tuned with high precision in a very broad band by combining a coarse control with the pumping source and a fine control with the optical frequency comb references. In our experimental setup, coarse and fine tuning resolutions were 4 MHz and 20 Hz, respectively. Influence of Brillouin pump fluctuations in the synthesized signal stability were also analyzed for observation times up to 104 s.

  3. Reflection of slow ions: effect of anisotropy of scattering on energy spectra

    International Nuclear Information System (INIS)

    Transport calculations based on linear Boltzmann equation have been carried out analytically for the reflection of low energy light ions from heavy targets. The collision integral of the ion transport equation is replaced by P3 approximation in angle. For power potentials the influence of the anisotropy of scattering on universal path length distribution of reflected particles is investigated. (author)

  4. 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.

  5. 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.

  6. 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.

  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. Infrared reflectance spectra: Effects of particle size, provenance and preparation

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.; Blake, Thomas A.; Forland, Brenda M.; Szecsody, James E.; Johnson, Timothy J.

    2014-09-22

    We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectance spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk 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. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures 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 observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.

  9. 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.

  10. 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.

  11. 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...

  12. Implementation of the multireference Brillouin-Wigner and Mukherjee’s coupled cluster methods with non-iterative triple excitations utilizing reference-level parallelism

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran-Nair, Kiran; Brabec, Jiri; Apra, Edoardo; van Dam, Hubertus JJ; Pittner, Jiri; Kowalski, Karol

    2012-09-07

    In this paper we discuss the performance of the non-iterative State-Specific Mul- tireference Coupled Cluster (SS-MRCC) methods accounting for the effect of triply excited cluster amplitudes. The corrections to the Brillouin-Wigner and Mukherjee MRCC models based on the manifold of singly and doubly excited cluster amplitudes (BW-MRCCSD and Mk-MRCCSD, respectively) are tested and compared with the exact full configuration interaction results (FCI) for small systems (H2O, N2, and Be3). For larger systems (naphthyne isomers and -carotene), the non-iterative BW-MRCCSD(T) and Mk-MRCCSD(T) methods are compared against the results obtained with the single reference coupled cluster methods. We also report on the parallel performance of the non-iterative implementations based on the use of pro- cessor groups.

  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. 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.

  15. 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.

  16. Surface and bulk scattering by magnetic and dielectric inhomogeneities: a first-order method

    International Nuclear Information System (INIS)

    The scattering of a magneto-dielectric multilayer has been studied by a first-order method. The model reported in this manuscript relies on the equivalence between heterogeneities of the medium and fictitious electric and magnetic sources. Types of inhomogeneities considered are roughness and bulk inhomogeneities and concern both permittivity and permeability. The numerical results are compared to those given in previous papers for optical scattering. It is shown in the microwave spectra that angle-resolved scattering allows identification of the scattering origins (permittivity or permeability spectra). The cases of isotropic films and meta-materials are presented and discussed. (authors)

  17. Surface and bulk scattering by magnetic and dielectric inhomogeneities: a first-order method.

    Science.gov (United States)

    Dieudonné, É; Malléjac, N; Amra, C; Enoch, S

    2013-09-01

    The scattering of a magnetodielectric multilayer has been studied by a first-order method. The model reported in this manuscript relies on the equivalence between heterogeneities of the medium and fictitious electric and magnetic sources. Types of inhomogeneities considered are roughness and bulk inhomogeneities and concern both permittivity and permeability. The numerical results are compared to those given in previous papers for optical scattering. It is shown in the microwave spectra that angle-resolved scattering allows identification of the scattering origins (permittivity or permeability spectra). The cases of isotropic films and metamaterials are presented and discussed. PMID:24323258

  18. 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.

  19. Scattering Equations and KLT Orthogonality

    OpenAIRE

    Cachazo, Freddy; He, Song; Yuan, Ellis Ye

    2013-01-01

    Several recent developments point to the fact that rational maps from n-punctured spheres to the null cone of D dimensional momentum space provide a natural language for describing the scattering of massless particles in D dimensions. In this note we identify and study equations relating the kinematic invariants and the puncture locations, which we call the scattering equations. We provide an inductive algorithm in the number of particles for their solutions and prove a remarkable property wh...

  20. 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)]....

  1. Supernova Neutrino Spectra and Applications to Flavor

    OpenAIRE

    Keil, Mathias Thorsten

    2007-01-01

    We study the flavor-dependent neutrino spectra formation in the core of a supernova (SN) by means of Monte Carlo simulations. Several neutrino detectors around the world are able to detect a high-statistics signal from a galactic SN. From such a signal one may extract information that severely constrains the parameter space for neutrino oscillations. Therefore, reliable predictions for flavor-dependent fluxes and spectra are urgently needed. In all hydrodynamic simulations the treatment of nu...

  2. One- and two-phonon raman scattering in ternary phosphides ZnSiP2, ZnGeP2, CdSiP2

    International Nuclear Information System (INIS)

    One- and two-phonon Raman scattering (RS) of orientated single crystals of ZnSiP2, ZnGeP2, and CdSiP2 are investigated. For the first time in ZnSiP2 the lattice vibrations B2(L/T) 146/145 and B1 466 cm-1 are observed, and the values of L-T splitting of polar modes are determined. It is concluded that in crystals of ZnGeP2, ZnSiP2, and CdSiP2 a completely symmetric component of the second-order RS spectra is formed by overtones and gives the distribution of the phonon state density of the lattice of these compounds. This distribution is determined in the main by the points GAMMA, T, N of Brillouin zone and has the general form for all compounds investigated. An estimation is given of the frequencies of inactive A2-phonons in ZnGeP2, ZnSiP2 and CdSiP2. (author)

  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. 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...

  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. 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)

  7. 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.

  8. 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...

  9. 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.

  10. 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

  11. Application of Brillouin optical correlation domain analysis for crack identification in concrete structure

    Science.gov (United States)

    Imai, Michio; Miura, Satoru

    2013-12-01

    This paper investigates the application of distributed optical fiber strain sensors to civil engineering structures, because no other tool can satisfactorily detect the location of the unpredictable phenomenon. In fact, the locations of cracks in the concrete structure are unknown a priori; therefore, a fully distributed sensor is necessary to detect them. The Brillouin optical correlation domain analysis (BOCDA), which offers high spatial resolution by using stimulated Brillouin scattering along the whole length of the optical fiber, is used in a wide range of civil engineering applications, and the same has undergone significant development over the last decade. In this paper, it is demonstrated how a BOCDA-based strain sensor can be employed to monitor cracks in concrete. Crack monitoring on the surface of the concrete member provides useful information for evaluating stiffness and durability of the structure, particularly for early detection of tiny cracks, which is essential for preventing crack growth and dispersion. The crack-induced strain distribution was analytically investigated, and it was proved that BOCDA can identify even a small crack before its visual recognition by a beam test. Moreover, periodical crack monitoring was successfully executed on a pedestrian deck for five years.

  12. A microrod-resonator Brillouin laser with 240 Hz absolute linewidth

    Science.gov (United States)

    Loh, William; Becker, Joe; Cole, Daniel C.; Coillet, Aurelien; Baynes, Fred N.; Papp, Scott B.; Diddams, Scott A.

    2016-04-01

    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 μm2, 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 Hz2 Hz‑1. 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 and mode frequency. We demonstrate the ability to reduce this noise through a feedback loop that stabilizes the intracavity power.

  13. 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...

  14. Temperature dependent Raman scattering and far-infrared reflectance spectra of MgO modified Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ceramics: A composition effect

    International Nuclear Information System (INIS)

    Lattice dynamics and phase transition of MgO modified Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 (PZTN-x wt. % MgO, x = 0, 0.1, 0.2, 0.5) ceramics have been investigated by far-infrared (FIR) reflectance in the temperature range of 5.5–300 K and Raman spectra between 77 and 300 K, respectively. With the aid of above complementary methods, the structure of all ceramics was defined as low-temperature ferroelectric rhombohedral phase [FR(LT)] at room temperature. The FIR dielectric functions were extracted from the multi-Lorentz oscillator dispersion model. The lowest frequency phonon mode, which is related to Pb-BO3 (B = Zr, Ti, Nb) vibration, mainly dominates the FIR dielectric response. With increasing MgO composition, the dielectric constants ε(0) at room temperature are estimated to 85.4, 73.4, 73.9, and 41.9, respectively. The decreasing trend can be due to the doubly ionized oxygen vacancies induced by Mg substitution for B-site. The order-disorder phase transition located around 120 K can be clearly clarified from temperature evolution of phonon frequency, damping, and intensity. It decreases slightly with increasing MgO composition, which influence the distortion due to the broken correlation chains and local permanent dipoles creation. Moreover, the transformation from antiferroelectric orthorhombic AO to [ FR(LT) ] phase has been observed around 250 K, which is associated with the antiferroelectric displacement of Pb atoms along 〈 110 〉 and coupled rotations of the corner-connected oxygen octahedral. Furthermore, the transition from [ FR(LT) ] to [ FR(HT) ] (high-temperature ferroelectric rhombohedral phase) was identified around 290 K for MgO-doped PZTN ceramics. It arises from the shift of cation (Pb and Zr/Ti/Nb/Mg ions) along the 〈 111 〉 direction and the transition temperature slightly decreases compared to the pure ceramic

  15. 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

  16. 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)

  17. 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.

  18. On Thom spectra, orientability, and cobordism

    CERN Document Server

    Rudyak, Yu B

    2007-01-01

    For many years, algebraic topology rests on three legs: 'ordinary' cohomology, K-theory, and cobordism. This book is the first guide on the subject of cobordism since R. Stong's encyclopaedic and influential notes of a generation ago. It concentrates on Thom spaces (spectra), orientability theory and (co)bordism theory (including (co)bordism with singularities and, in particular, Morava K-theories), framed by (co)homology theories and spectra. From the Foreword by Haynes Miller The author has also performed a service to the history of science in this book, giving detailed attributions. This sa

  19. 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...

  20. Scattering Equations and KLT Orthogonality

    CERN Document Server

    Cachazo, Freddy; Yuan, Ellis Ye

    2013-01-01

    Several recent developments point to the fact that rational maps from n-punctured spheres to the null cone of D dimensional momentum space provide a natural language for describing the scattering of massless particles in D dimensions. In this note we identify and study equations relating the kinematic invariants and the puncture locations, which we call the scattering equations. We provide an inductive algorithm in the number of particles for their solutions and prove a remarkable property which we call KLT Orthogonality. In a nutshell, KLT orthogonality means that "Parke-Taylor" vectors constructed from the solutions to the scattering equations are mutually orthogonal with respect to the Kawai-Lewellen-Tye (KLT) bilinear form. We end with comments on possible connections to gauge theory and gravity amplitudes in any dimension and to the high-energy limit of string theory amplitudes.