WorldWideScience

Sample records for optical rotatory dispersion

  1. Quantum optical rotatory dispersion

    Science.gov (United States)

    Tischler, Nora; Krenn, Mario; Fickler, Robert; Vidal, Xavier; Zeilinger, Anton; Molina-Terriza, Gabriel

    2016-01-01

    The phenomenon of molecular optical activity manifests itself as the rotation of the plane of linear polarization when light passes through chiral media. Measurements of optical activity and its wavelength dependence, that is, optical rotatory dispersion, can reveal information about intricate properties of molecules, such as the three-dimensional arrangement of atoms comprising a molecule. Given a limited probe power, quantum metrology offers the possibility of outperforming classical measurements. This has particular appeal when samples may be damaged by high power, which is a potential concern for chiroptical studies. We present the first experiment in which multiwavelength polarization-entangled photon pairs are used to measure the optical activity and optical rotatory dispersion exhibited by a solution of chiral molecules. Our work paves the way for quantum-enhanced measurements of chirality, with potential applications in chemistry, biology, materials science, and the pharmaceutical industry. The scheme that we use for probing wavelength dependence not only allows one to surpass the information extracted per photon in a classical measurement but also can be used for more general differential measurements. PMID:27713928

  2. Bragg reflection band width and optical rotatory dispersion of cubic blue-phase liquid crystals

    Science.gov (United States)

    Yoshida, Hiroyuki; Anucha, Konkanok; Ogawa, Yasuhiro; Kawata, Yuto; Ozaki, Masanori; Fukuda, Jun-ichi; Kikuchi, Hirotsugu

    2016-10-01

    The Bragg reflection band width and optical rotatory dispersion of liquid crystalline cholesteric blue phases (BPs) I and II are compared by numerical simulations. Attention is paid to the wavelength regions for which the reflection bands with lowest photon energies appear, i.e., the [110 ] direction for BP I and the [100 ] direction for BP II. Finite difference time domain and 4 ×4 matrix calculations performed on the theoretical director tensor distribution of BPs with the same material parameters show that BP II, which has simple cubic symmetry, has a wider photonic band gap than BP I, which has body centered cubic symmetry, possibly due to the fact that the density of the double-twist cylinders in BP II are twice that in BP I. The theoretical results on the Bragg reflection band width are supported by reflectance measurements performed on BPs I and II for light incident along the [110 ] and [100 ] directions, respectively.

  3. Quartz optical filter for wavelength selection of frequency-doubled laser based on optical rotatory dispersion effect

    Institute of Scientific and Technical Information of China (English)

    Shan Zhang; Fuquan Wu; Wendi Wu; Haifeng Wang

    2007-01-01

    Based on the optical rotatory dispersion effect, an optical filter for selecting the second harmonic of a frequency-doubled laser is constructed from quartz in combination with polarizers. The operating principle is analyzed by matrix formulation, and the result indicates that the second harmonic of a frequency-doubled laser will be obtained when the rotation angle has a difference of (2n + 1)π/2 (n = 0, 1, 2, 3,… ) between the two polarizations of the second-harmonic laser and the fundamental laser. The spectrum of the output laser is taken by the AQ-6315A spectrometer, and the experimental results are in good agreement with the theoretical results.

  4. New method to determine the optical rotatory dispersion of inorganic crystals applied to some samples of Carpathian Quartz.

    Science.gov (United States)

    Dimitriu, Dan Gheorghe; Dorohoi, Dana Ortansa

    2014-10-15

    A new method to determine the optical rotatory dispersion (ORD) in the visible range, based on a channeled spectrum obtained with a uniax inorganic crystal introduced between two crossed polarizers with its optical axis parallel to the light propagation direction is detailed in this paper. When the studied inorganic crystals are transparent, this method permits the estimation of the optical rotatory dispersion in the visible range, for which the cheap polarizers are available. The speed of the measurements is very high, because the estimations are made from the channeled spectrum obtained for a single arrangement of the optical components. By using a computer, ORD is quickly determined for the visible range. The results obtained by this method for some Carpathian Quartz samples are consistent with those from literature. The proposed method can be also applied in UV and IR spectral ranges, when the anisotropic layers are transparent and the linearly polarized radiations can be obtained.

  5. Solvent, temperature and concentration effects on the optical rotatory dispersion of (R)-3-methylcyclohexanone

    Science.gov (United States)

    Alenaizan, Asem; Al-Basheer, Watheq; Musa, Musa M.

    2017-02-01

    Optical rotatory dispersion (ORD) spectra are reported for isolated and solvated (R)-3-methylcyclohexanone (R-3MCH) in 10 solvents, of wide polarity range, and over the spectral range 350-650 nm. Sample concentration effects on ORD spectra of R-3MCH were also recorded and investigated over widely varying concentrations from 2.5 × 10-3 to 2.5 × 10-1 g/mL where an observed sensitivity of optical rotation (OR) to incident light wavelength at low concentrations is correlated to solvent effects. Temperature effects were also studied by recording ORD spectra over the temperature range 0-65 °C in toluene. Recorded specific OR was plotted against various solvent parameters, namely, dipole moment, polarity, refractive index and polarizability to probe solvent effects. Furthermore, solvent effects were studied by incorporating Kamlet's and Taft's solvent parameters in the multi-parametric linear fitting. Theoretically, ORD spectra and populations of optimized geometries of equatorial and axial conformers of R-3MCH were calculated in the gas and solvated phases. All theoretical calculations were performed employing the polarizable continuum model using density functional theoretical and composite scheme (G4) methods with aug-cc-pVTZ and aug-cc-pVDZ basis sets. Net ORD spectra of R-3MCH were generated by the Boltzmann-weighted sum of the contributions of the dominant conformers. Upon comparing theoretical and experimental ORD spectra, a very good agreement is observed for the ORD spectra in the gas phase and high polarity solvents compared to relatively lesser agreement in low polarity solvents.

  6. Measurement of Rotatory Optics Element in Tensor Dielectric Matrix for Rotatory Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    LIU Jinghao; ZHANG Xiaofan; LI Huazhou; BAO Zhenwu

    2005-01-01

    The rotatory optics element in the tensor dielectric coefficient matrix is an important parameter for analyzing and calculating a rotatory optical fiber by electromagnetic theory. But the mea-surement of rotatory optics element is difficult for the rotatory optical fiber. A simple principle and method for measuring rotatory optics element are put forward in this paper. Firstly by using electromagnetic theory it was demonstrated that the rotatory optics element has a simple linear relation with the rotatory angle, and then the rotatory optics element has a simple linear relation with the magnetic field strength (or bias current in the helix coil) . Secondly a measurement system for the rotatory optics element in the rotatory optical fiber was designed. Using the measurement system the rotatory element can be obtained by measuring the bias current simply.

  7. Faraday rotation dispersion measurements of diamagnetic organic liquids and simultaneous determination of natural optical rotatory dispersion using a pulsed magnetic field.

    Science.gov (United States)

    Suwa, Masayori; Miyamoto, Kayoko; Watarai, Hitoshi

    2013-01-01

    We constructed an apparatus to measure the wavelength dispersion of the Faraday rotation in the visible region, and determined the Verdet constants of diamagnetic organic liquids, including aliphatic compounds, benzene derivatives, and naphthalene derivatives. These three groups were easily distinguished by the magnitudes of their Verdet constants. Based on the theory developed by Serber, we determined the enhancing effect of π*←π transitions on the visible-light Faraday rotation angles observed for aromatic compounds. Furthermore, we propose a novel approach for simultaneously observing Faraday rotation dispersion and natural optical rotatory dispersion.

  8. Stereochemistry of the tadalafil diastereoisomers: a critical assessment of vibrational circular dichroism, electronic circular dichroism, and optical rotatory dispersion.

    Science.gov (United States)

    Qiu, Shi; De Gussem, Ewoud; Tehrani, Kourosch Abbaspour; Sergeyev, Sergey; Bultinck, Patrick; Herrebout, Wouter

    2013-11-14

    The stereochemistry of all four stereoisomers of tadalafil is determined using vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotatory dispersion (ORD) spectroscopy. By comparing experimentally obtained VCD spectra to computationally simulated ones, the absolute configuration of the enantiomeric pair (6R, 12aR)/(6S, 12aS) can be confidently assigned without prior knowledge of their relative stereochemistry. IR and NMR spectra are used to aid the assignment of the relative stereochemistry. The IR and VCD difference spectra further confirm the assignment of all stereoisomers. ECD and ORD spectra are used to investigate the complementarity of the three chiroptical techniques. VCD spectroscopy itself is found to have the ability to identify diastereoisomers, and simultaneous use of these chiroptical spectroscopic methods and NMR chemical shifts aids in increasing the reliability of stereochemistry assignment of diastereoisomers.

  9. Radioracemization and radiation-induced chiral amplification of chiral terpenes measured by optical rotatory dispersion (ORD) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Franco [Lupi Chemical Research Institute, Via Casilina 1626/A, 00133 Rome (Italy); INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania (Italy)], E-mail: franco.cataldo@fastwebnet.it; Ursini, Ornella; Angelini, Giancarlo [Institute of Chemical Methodologies, CNR Via Salaria Km. 29300 00016 Monterotondo Stazione, Rome (Italy)

    2008-08-15

    For the first time the radioracemization of {alpha}(+)pinene and {alpha}(-)pinene, of turpentine and of R(-)-{alpha}-phellandrene has been studied by optical rotatory dispersion (ORD) spectroscopy. For all these compounds, the radioracemization implies a shift of the ORD curves toward lower levels of specific optical rotation. The radioracemization degree (R{sub R}) has been defined and calculated for all the compounds studied. It has been found that for radiation dose of 1 MGy the radioracemization degree is about 4.5% for the compound with the highest optical purity and reaches 7-8% for the less optically pure compounds, demonstrating that impurities can affect greatly the radioracemization. In contrast with the general radioracemization effect exerted by high-energy radiation on chiral molecules, {beta}(-)pinene, {beta}(+)pinene when irradiated show an increment of their specific optical rotation. This fact has been measured for the first time by ORD spectroscopy and the amplification degree of chirality can reach 1000% in the near UV. This phenomenon is due to the formation of a chiral polymer, poly-{beta}-pinene, which forms a solution with the monomer enhancing its optical activity. The implications for the theories of the origin of life of such unexpected phenomenon are discussed briefly.

  10. Absolute configuration of an axially chiral sulfonate determined from its optical rotatory dispersion, electronic circular dichroism, and vibrational circular dichroism spectra.

    Science.gov (United States)

    Covington, Cody L; Raghavan, Vijay; Smuts, Jonathan P; Armstrong, Daniel W; Polavarapu, Prasad L

    2017-11-01

    The absolute configuration (AC) of an axially chiral sulfonate (aCSO), 3,5-dimethyl-2-(naphthalen-1-yl)-6-(naphthalen-1-yl)benzenesulfonate (labeled as aCSO5), was investigated using optical rotatory dispersion (ORD), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) spectroscopies. All three methods led to the same conclusion and the AC of aCSO5 is reliably determined to be (-)-(aR, aR), or conversely (+)-(aS, aS). © 2017 Wiley Periodicals, Inc.

  11. Influence of Physical and Chemical Modification on the Optical Rotatory Dispersion and Biological Activity of Chitosan Films

    Directory of Open Access Journals (Sweden)

    A. B. Shipovskaya

    2013-01-01

    Full Text Available The optical and bactericidal properties of acetic and basic chitosan films were studied. By the ORD technique, we found that these films differed in the values of their specific optical rotation and of their rotary and dispersive constants. A sign inversion of was observed when the acetic chitosan films were heat-treated. The bactericidal activity of the initial and dehydrated acetic films was analyzed, and their moisture content and optical and biological activities were compared.

  12. Kramers-Kronig transformation of experimental electronic circular dichroism: application to the analysis of optical rotatory dispersion in dimethyl-L-tartrate.

    Science.gov (United States)

    Polavarapu, Prasad L; Petrovic, Ana G; Zhang, Peng

    2006-09-01

    When a limited region of the experimental electronic circular dichroism (ECD) spectrum is subjected to Kramers-Kronig (KK) transformation, the resulting optical rotatory dispersion (ORD) may or may not reproduce the experimentally measured ORD in the long-wavelength nonresonant region. If the KK transform of experimentally measured ECD in a limited wavelength region reproduces the experimentally measured ORD in the long-wavelength nonresonant region, then that observation indicates that the ORD in the long-wavelength nonresonant region should be satisfactorily predicted from the correspondingly limited number of electronic transitions in a reliable quantum mechanical calculation. On the other hand, if the KK transform of experimentally measured ECD in a limited region does not reproduce the experimentally measured ORD in the long-wavelength nonresonant region, then it should be possible to identify the ECD bands in the shorter wavelength region that are responsible for the differences between experimentally observed ORD and KK-transformed ECD. This approach helps to identify the role of ECD associated with higher energy-excited states in the nature of ORD in the long-wavelength nonresonant region. These concepts are demonstrated here by measuring the experimental ECD and ORD for dimethyl-L-tartrate in different solvents. While ECD spectra of dimethyl-L-tartrate in different solvents show little variation, ORD spectra in the long-wavelength nonresonant region show marked solvent dependence. These observations are explained using the difference between experimental ORD and KK-transformed ECD. Quantum mechanical predictions of ECD and ORD are also presented for isolated (R, R)-dimethyl tartrate at the B3LYP/aug-cc-pVDZ level.

  13. On the transferability of atomic contributions to the optical rotatory power of hydrogen peroxide, methyl hydroperoxide and dimethyl peroxide

    DEFF Research Database (Denmark)

    Sánchez, Marina; Alkorta, Ibon; Elguero, José

    2014-01-01

    The chirality of molecules expresses itself, for example, in the fact that a solution of a chiral molecule rotates the plane of linear polarised light. The underlying molecular property is the optical rotatory power (ORP) tensor, which according to time-dependent perturbation theory can be calcul...

  14. Amplified Dispersive Optical Tomography

    CERN Document Server

    Goda, Keisuke; Jalali, Bahram

    2008-01-01

    Optical coherence tomography (OCT) has proven to be a powerful technique for studying tissue morphology in ophthalmology, cardiology, and endomicroscopy. Its performance is limited by the fundamental trade-off between the imaging sensitivity and acquisition speed -- a predicament common in virtually all imaging systems. In this paper, we circumvent this limit by using distributed Raman post-amplification of the reflection from the sample. We combine the amplification with simultaneously performed dispersive Fourier transformation, a process that maps the optical spectrum into an easily measured time-domain waveform. The Raman amplification enables measurement of weak signals which are otherwise buried in noise. It extends the depth range without sacrificing the acquisition speed or causing damage to the sample. As proof of concept, single-shot imaging with 15 dB improvement in sensitivity at an axial scan rate of 36.6 MHz is demonstrated.

  15. Faraday anomalous dispersion optical tuners

    Science.gov (United States)

    Wanninger, P.; Valdez, E. C.; Shay, T. M.

    1992-01-01

    Common methods for frequency stabilizing diode lasers systems employ gratings, etalons, optical electric double feedback, atomic resonance, and a Faraday cell with low magnetic field. Our method, the Faraday Anomalous Dispersion Optical Transmitter (FADOT) laser locking, is much simpler than other schemes. The FADOT uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. This method is vibration insensitive, thermal expansion effects are minimal, and the system has a frequency pull in range of 443.2 GHz (9A). Our technique is based on the Faraday anomalous dispersion optical filter. This method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters. We present the first theoretical model for the FADOT and compare the calculations to our experimental results.

  16. Faraday anomalous dispersion optical filters

    Science.gov (United States)

    Shay, T. M.; Yin, B.; Alvarez, L. S.

    1993-01-01

    The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.

  17. Optical angular momentum in dispersive media

    CERN Document Server

    Philbin, T G

    2012-01-01

    The angular momentum density and flux of light in a dispersive, rotationally symmetric medium are derived from Noether's theorem. Optical angular momentum in a dispersive medium has no simple relation to optical linear momentum, even if the medium is homogeneous. A circularly polarized monochromatic beam in a homogeneous, dispersive medium carries a spin angular momentum per unit energy of $\\pm\\omega^{-1}$, as in vacuum. This result demonstrates the non-trivial interplay of dispersive contributions to optical angular momentum and energy.

  18. A potassium Faraday anomalous dispersion optical filter

    Science.gov (United States)

    Yin, B.; Shay, T. M.

    1992-01-01

    The characteristics of a potassium Faraday anomalous dispersion optical filter operating on the blue and near infrared transitions are calculated. The results show that the filter can be designed to provide high transmission, very narrow pass bandwidth, and low equivalent noise bandwidth. The Faraday anomalous dispersion optical filter (FADOF) provides a narrow pass bandwidth (about GHz) optical filter for laser communications, remote sensing, and lidar. The general theoretical model for the FADOF has been established in our previous paper. In this paper, we have identified the optimum operational conditions for a potassium FADOF operating on the blue and infrared transitions. The signal transmission, bandwidth, and equivalent noise bandwidth (ENBW) are also calculated.

  19. Optical waveguide materials, structures, and dispersion modulation

    Science.gov (United States)

    Zhang, Hao; Liu, Jiaming; Lin, Jian; Li, Wenxiu; Xue, Xia; Huang, Anping; Xiao, Zhisong

    2016-11-01

    Optical waveguide is used in most integrated optic devices to confine and guide light in higher refractive index channels. The structures and materials of slot waveguides are reviewed in this paper. Coupled resonator optical waveguides (CROWs) can be used for a rotation sensor with compact size, low power consumption and low cost. The loss determines the ultimate sensitivity of CROW gyros. Resonator-based optical gyroscope's sensitivity for measuring rotation is enhanced via using the anomalous dispersion characteristic of superluminal light propagation, which can be also generated by using passive optical resonators.

  20. Pulse dispersion in hollow optical waveguides

    Science.gov (United States)

    Ben-David, M.; Ilev, Ilko K.; Waynant, Ronald W.; Gannot, Israel

    2005-09-01

    A study of laser (near- and mid-infrared) pulse dispersion in hollow waveguides is presented. We developed an analytical model to describe the pulse dispersion in hollow waveguides and compared our theoretical calculations with measurements done by us and also by two other groups. The pulse dispersion was experimentally measured for a short Q-switched Er:YAG laser in the nanosecond range and for femtosecond Ti:sapphire laser pulses transmitted by hollow optical waveguides. For analytical calculation of the pulse dispersion in these waveguides, a refined ray tracing program was developed. This approach took into account roughness of the internal reflecting and refracting inner layers. A comparison analysis between the measurements and calculations conducted at identical parameters demonstrates good correlation between theoretical and experimental results.

  1. Generalized dispersive wave emission in nonlinear fiber optics.

    Science.gov (United States)

    Webb, K E; Xu, Y Q; Erkintalo, M; Murdoch, S G

    2013-01-15

    We show that the emission of dispersive waves in nonlinear fiber optics is not limited to soliton-like pulses propagating in the anomalous dispersion regime. We demonstrate, both numerically and experimentally, that pulses propagating in the normal dispersion regime can excite resonant dispersive radiation across the zero-dispersion wavelength into the anomalous regime.

  2. Measurement of small dispersion values in optical components

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Liu, Fenghai; Pedersen, Rune Johan Skullerud

    1999-01-01

    It is reported that small dispersion values in optical components can be measured using the RF modulation method originally restricted to large dispersions. Using a constant dispersion offset, arbitrarily small dispersion values can be measured with a resolution as good as 1.2 ps/nm.......It is reported that small dispersion values in optical components can be measured using the RF modulation method originally restricted to large dispersions. Using a constant dispersion offset, arbitrarily small dispersion values can be measured with a resolution as good as 1.2 ps/nm....

  3. The Function of the Magnetic-Optic Modulation in the Very Small Rotatory Angle of Polarization%磁光调制技术在光偏振微小旋转角精密测量中的应用

    Institute of Scientific and Technical Information of China (English)

    钱小陵; 常悦

    2001-01-01

    An experimental device is introduced which improves themeasurement accuracy of polarimetry very small rotatory angle of polarization to the magnitude of 10-4 degree by applying the magnetic-optic modulation. The working principles of the device is described in details and the data obtained from the experiment is also provided%提供了一种实验装置,在光偏振微小旋转角的测量中,应用磁光调制技术,对薄膜样品的克尔效应、药物原料的旋光效应和化学试剂的费尔德常数进行了观测、测量.其中在费尔德常数的测量中,精度达到了亚毫度的数量级.详细介绍了该装置的工作原理,以及在实验中获得的数据.

  4. Normal dispersion femtosecond fiber optical parametric oscillator.

    Science.gov (United States)

    Nguyen, T N; Kieu, K; Maslov, A V; Miyawaki, M; Peyghambarian, N

    2013-09-15

    We propose and demonstrate a synchronously pumped fiber optical parametric oscillator (FOPO) operating in the normal dispersion regime. The FOPO generates chirped pulses at the output, allowing significant pulse energy scaling potential without pulse breaking. The output average power of the FOPO at 1600 nm was ∼60  mW (corresponding to 1.45 nJ pulse energy and ∼55% slope power conversion efficiency). The output pulses directly from the FOPO were highly chirped (∼3  ps duration), and they could be compressed outside of the cavity to 180 fs by using a standard optical fiber compressor. Detailed numerical simulation was also performed to understand the pulse evolution dynamics around the laser cavity. We believe that the proposed design concept is useful for scaling up the pulse energy in the FOPO using different pumping wavelengths.

  5. Optical glass: dispersion in the near infrared

    Science.gov (United States)

    Hartmann, Peter

    2011-10-01

    With deliveries of optical glass lots measurement data are given for the visible range usually from 436 nm (g-line) to 656 nm (C-line). Sometimes the question arises if refractive index values in the near infrared can be calculated from these data. With near infrared we mean the range from the C-line up to 1700 nm in this publication. The reason is that up to 1700 nm most optical glasses have hardly any reduction in their transmission. On the basis of a large amount of production data obtained over more than ten years with precision v-block refractometer evaluations are possible up to 1014 nm. The precision spectrometer URIS developed by SCHOTT enables to analyze the refractive index with measurement uncertainty fairly below 10-5 for even longer wavelengths up to 2325 nm, however on a much smaller data basis. The variability of the IR dispersion is shown for selected glass types. Frequency distributions for the different deviation shapes give information how reliable extrapolations are from the visible range to the near IR. The precision refractometer data were used to simulate such extrapolations employing partial dispersion data from catalog data sheets and to check the consistency of simulated with real data. For some glass types extrapolations seem to be possible. However, there are also glass types, where the method using catalog partial dispersions leads to significant deviations from reality. So if extrapolations are intended to be done, a general check should be performed if this is justified for the glass type of interest.

  6. Novel applications of the dispersive optical model

    CERN Document Server

    Dickhoff, W H; Mahzoon, M H

    2016-01-01

    A review of recent developments of the dispersive optical model (DOM) is presented. Starting from the original work of Mahaux and Sartor, several necessary steps are developed and illustrated which increase the scope of the DOM allowing its interpretation as generating an experimentally constrained functional form of the nucleon self-energy. The method could therefore be renamed as the dispersive self-energy method. The aforementioned steps include the introduction of simultaneous fits of data for chains of isotopes or isotones allowing a data-driven extrapolation for the prediction of scattering cross sections and level properties in the direction of the respective drip lines. In addition, the energy domain for data was enlarged to include results up to 200 MeV where available. An important application of this work was implemented by employing these DOM potentials to the analysis of the (\\textit{d,p}) transfer reaction using the adiabatic distorted wave approximation (ADWA). We review the fully non-local DOM...

  7. Nonlinear and Dispersive Optical Pulse Propagation

    Science.gov (United States)

    Dijaili, Sol Peter

    In this dissertation, there are basically four novel contributions to the field of picosecond pulse propagation and measurement. The first contribution is the temporal ABCD matrix which is an analog of the traditional ABCD ray matrices used in Gaussian beam propagation. The temporal ABCD matrix allows for the easy calculation of the effects of linear chirp or group velocity dispersion in the time domain. As with Gaussian beams in space, there also exists a complete Hermite-Gaussian basis in time whose propagation can be tracked with the temporal ABCD matrices. The second contribution is the timing synchronization between a colliding pulse mode-locked dye laser and a gain-switched Fabry-Perot type AlGaAs laser diode that has achieved less than 40 femtoseconds of relative timing jitter by using a pulsed optical phase lock loop (POPLL). The relative timing jitter was measured using the error voltage of the feedback loop. This method of measurement is accurate since the frequencies of all the timing fluctuations fall within the loop bandwidth. The novel element is a broad band optical cross-correlator that can resolve femtosecond time delay errors between two pulse trains. The third contribution is a novel dispersive technique of determining the nonlinear frequency sweep of a picosecond pulse with relatively good accuracy. All the measurements are made in the time domain and hence there is no time-bandwidth limitation to the accuracy. The fourth contribution is the first demonstration of cross -phase modulation in a semiconductor laser amplifier where a variable chirp was observed. A simple expression for the chirp imparted on a weak signal pulse by the action of a strong pump pulse is derived. A maximum frequency excursion of 16 GHz due to the cross-phase modulation was measured. A value of 5 was found for alpha _{xpm} which is a factor for characterizing the cross-phase modulation in a similar manner to the conventional linewidth enhancement factor, alpha.

  8. Theoretical model for a Stark anomalous dispersion optical filter

    Science.gov (United States)

    Yin, B.; Shay, T. M.

    1993-01-01

    A theoretical model for the first atomic Stark anomalous dispersion optical filter is reported. The results show the filter may serve as a widely tunable narrow bandwidth and high throughput optical filter for freespace laser communications and remote sensing.

  9. Novel applications of the dispersive optical model

    Science.gov (United States)

    Dickhoff, W. H.; Charity, R. J.; Mahzoon, M. H.

    2017-03-01

    A review of recent developments of the dispersive optical model (DOM) is presented. Starting from the original work of Mahaux and Sartor, several necessary steps are developed and illustrated which increase the scope of the DOM allowing its interpretation as generating an experimentally constrained functional form of the nucleon self-energy. The method could therefore be renamed as the dispersive self-energy method. The aforementioned steps include the introduction of simultaneous fits of data for chains of isotopes or isotones allowing a data-driven extrapolation for the prediction of scattering cross sections and level properties in the direction of the respective drip lines. In addition, the energy domain for data was enlarged to include results up to 200 MeV where available. An important application of this work was implemented by employing these DOM potentials to the analysis of the (d, p) transfer reaction using the adiabatic distorted wave approximation. We review these calculations which suggest that physically meaningful results are easier to obtain by employing DOM ingredients as compared to the traditional approach which relies on a phenomenologically-adjusted bound-state wave function combined with a global (nondispersive) optical-model potential. Application to the exotic 132Sn nucleus also shows great promise for the extrapolation of DOM potentials towards the drip line with attendant relevance for the physics of FRIB. We note that the DOM method combines structure and reaction information on the same footing providing a unique approach to the analysis of exotic nuclei. We illustrate the importance of abandoning the custom of representing the non-local Hartree–Fock (HF) potential in the DOM by an energy-dependent local potential as it impedes the proper normalization of the solution of the Dyson equation. This important step allows for the interpretation of the DOM potential as representing the nucleon self-energy permitting the calculations of

  10. Atlantoaxial rotatory dislocation. A case report.

    Science.gov (United States)

    Niibayashi, H

    1998-07-01

    Report of a child who sustained an acute atlantoaxial rotatory dislocation, associated with fractures of the clavicle and the temporal bone, and rupture of the alar ligament demonstrated by magnetic resonance imaging. To describe the radiographic and pathoanatomic characteristics of the injury process. Only five cases of traumatic atlantoaxial rotatory dislocation associated with fracture of the clavicle have been reported previously. This is the first report of a ruptured alar ligament demonstrated on magnetic resonance imaging in a patient with atlantoaxial rotatory dislocation associated with fractures of the clavicle and the temporal bone. Computed tomography revealed the Type 1 rotatory dislocation described by Fielding and Hawkins, and magnetic resonance imaging delineated the ruptured alar ligament. Traction in a halter, followed by 6 weeks of immobilization with a cervical collar, was successful in the management of the injury. Concomitant fractures of the right temporal bone and the right clavicle may yield excessive left rotation of the atlas on the axis, resulting in the rupture of the right alar ligament. Awareness of this condition allows early diagnosis and effective conservative treatment.

  11. Time domain dispersion of underwater optical wireless communication

    Institute of Scientific and Technical Information of China (English)

    Wei Wei; Xiaohui Zhang; Jionghui Rao; Wenbo Wang

    2011-01-01

    @@ A new method to count the expected value and variance of time dispersion is presented for time dispersion of underwater optical wireless communication.Instead of the typically used Gamma distribution, inverse-Gaussian distribution is suggested for underwater optical impulse response time waveform function.The expectation of this method is in good agreement with experimental data.Future works may include water absorption to the model.%A new method to count the expected value and variance of time dispersion is presented for time dispersion of underwater optical wireless communication.Instead of the typically used Gamma distribution, inverseGaussian distribution is suggested for underwater optical impulse response time waveform function.The expectation of this method is in good agreement with experimental data.Future works may include water absorption to the model.

  12. Dispersive Optical Interface Based on Nanofiber-Trapped Atoms

    CERN Document Server

    Dawkins, S T; Reitz, D; Vetsch, E; Rauschenbeutel, A

    2011-01-01

    We dispersively interface an ensemble of one thousand atoms trapped in the evanescent field surrounding a tapered optical nanofiber. This method relies on the azimuthally-asymmetric coupling of the ensemble with the evanescent field of an off-resonant probe beam, transmitted through the nanofiber. The resulting birefringence and dispersion are significant; we observe a phase shift per atom of $\\sim$\\,1\\,mrad at a detuning of six times the natural linewidth, corresponding to an effective resonant optical density per atom of 2.7\\,%. Moreover, we utilize this strong dispersion to non-destructively determine the number of atoms.

  13. Spatial and temporal pulse propagation for dispersive paraxial optical systems.

    Science.gov (United States)

    Marcus, G

    2016-04-04

    The formalism for pulse propagation through dispersive paraxial optical systems first presented by Kostenbauder (IEEE J. Quant. Elec.261148-1157 (1990)) using 4 × 4 ray-pulse matrices is extended to 6 × 6 matrices and includes non-separable spatial-temporal couplings in both transverse dimensions as well as temporal dispersive effects up to a quadratic phase. The eikonal in a modified Huygens integral in the Fresnell approximation is derived and can be used to propagate pulses through complicated dispersive optical systems within the paraxial approximation. In addition, a simple formula for the propagation of ultrashort pulses having a Gaussian profile both spatially and temporally is presented.

  14. Achromatic metasurface optical components by dispersive phase compensation

    CERN Document Server

    Aieta, Francesco; Genevet, Patrice; Capasso, Federico

    2014-01-01

    The replacement of bulk refractive elements with flat ones enables the miniaturization of optical components required for integrated optical systems. This process comes with the limitation that planar optics suffers from large chromatic aberrations due to the dispersion of the phase accumulated by light during propagation. We show that this limitation can be overcome by compensating the dispersion of the propagation phase with the wavelength-dependent phase shift imparted by a metasurface. We demonstrate dispersion-free multi-wavelength dielectric metasurface deflectors in the near-infrared and design an achromatic flat lens in the same spectral region. Our design is based on low-loss coupled dielectric resonators, which introduce a dense spectrum of modes to enable dispersive phase compensation. Achromatic metasurfaces will find applications as multi-band-pass filters, lightweight collimators, and chromatically-corrected imaging lenses.

  15. Controllable Dispersion in an Optical Laser Gyroscope

    Science.gov (United States)

    Wolfe, Owen; Du, Shuangli; Rochester, Simon; Budker, Dmitry; Novikova, Irina; Mikhailov, Eugeniy

    2016-05-01

    Optical gyroscopes use Sagnac interferometry to make precise measurements of angular velocity. Increased gyroscope sensitivity will allow for more accurate control of aerospace systems and allow for more precise measurements of the Earth's rotation. Severalfold improvements to optical gyroscope sensitivity were predicted for fast light regimes (ng gyroscope response via tuning the experimental parameters. Gyroscope sensitivity was shown to be dependent on several parameters including pump power, pump detunning, and vapor density. This work was supported by the NSF and Naval Air Warfare Center STTR program N68335-11-C-0428.

  16. Dispersion penalty analysis for VSR-1 optical links

    Institute of Scientific and Technical Information of China (English)

    JIA Jiu-chun; CHEN Hong-da; CHEN Xiong-bin; ZHOU Yi

    2006-01-01

    This paper presents an approach to calculate dispersion penalty for VSR-1 optical links.Based on parameters of a specific VSR-1 link,dispersion penalties are computed for various modal dispersion bandwidths respectively.The worst-case eye closure is expressed numerically by using the signal waveform at time 0,and the signal waveform is obtained in frequency domain through FFT algorithm.By this approach,the dispersion penalty is determined by the shape of transfer functions of the various components in the links.To simplify the derivation of multimode fiber link transfer function,a Gaussian form of normalized impulse response is used.This calculation approach can be used to estimate the worst-case dispersion penalty of VSR-1 links in the link budget analysis.

  17. Optical properties of chitosan in aqueous solution of L- and D-ascorbic acids

    Science.gov (United States)

    Malinkina, Olga N.; Shipovskaya, Anna B.; Kazmicheva, Olga F.

    2016-04-01

    The optical properties of aqueous chitosan solutions in L- and D-ascorbic acids were studied by optical rotatory dispersion and spectrophotometry. The specific optical rotation [α] of all chitosan solutions tested was positive, in contrast to aqueous solutions of the ascorbic acid enantiomers, which exhibit an inverse relationship of [α] values. Significant differences in the absolute values of [α] of the chitosan solutions at polymer-acid ratios exceeding the equimolar one were found.

  18. Subcarrier multiplexing tolerant dispersion transmission system employing optical broadband sources.

    Science.gov (United States)

    Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

    2009-03-16

    This paper presents a novel SCM optical transmission system for next-generation WDM-PONs combining broadband optical sources and a Mach-Zehnder interferometric structure. The approach leeds to transport RF signals up to 50 GHz being compatible with RoF systems since a second configuration has been proposed in order to overcome dispersion carrier suppression effect using DSB modulation. The theoretical analysis validates the potentiality of the system also considering the effects of the dispersion slope over the transmission window.

  19. Non-dispersive optics using storage of light

    CERN Document Server

    Karpa, Leon

    2010-01-01

    We demonstrate the non-dispersive deflection of an optical beam in a Stern-Gerlach magnetic field. An optical pulse is initially stored as a spin-wave coherence in thermal rubidium vapour. An inhomogeneous magnetic field imprints a phase gradient onto the spin wave, which upon reacceleration of the optical pulse leads to an angular deflection of the retrieved beam. We show that the obtained beam deflection is non-dispersive, i.e. its magnitude is independent of the incident optical frequency. Compared to a Stern-Gerlach experiment carried out with propagating light under the conditions of electromagnetically induced transparency, the estimated suppression of the chromatic aberration reaches 10 orders of magnitude.

  20. Dispersion Compensation Requirements for Optical CDMA Using WDM Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, A J; Hendandez, V J; Feng, H X C; Heritage, J P; Lennon, W J

    2001-12-10

    Optical code division multiple access (O-CDMA) uses very narrow transmission pulses and is thus susceptible to fiber optic link impairments. When the O-CDMA is implemented as wavelength/time (W/T) matrices which use wavelength division multiplexing (WDM) sources such as multi-frequency laser transmitters, the susceptibility may be higher due to: (a) the large bandwidth utilized and (b) the requirement that the various wavelength components of the codes be synchronized at the point of modulation and encoding as well as after (optical) correlation. A computer simulation based on the nonlinear Schroedinger equation, developed to study optical networking on the National Transparent Optical Network (NTON), was modified to characterize the impairments on the propagation and decoding of W/T matrix codes over a link of the NTON. Three critical link impairments were identified by the simulation: group velocity dispersion (GVD); the flatness of the optical amplifier gain; and the slope of the GVD. Subsequently, experiments were carried out on the NTON link to verify and refine the simulations as well as to suggest improvements in the W/T matrix signal processing design. The NTON link measurements quantified the O-CDMA dispersion compensation requirements. Dispersion compensation management is essential to assure the performance of W/T matrix codes.

  1. Nonlocal dispersive optical model ingredients for ${}^{40}$Ca

    CERN Document Server

    Mahzoon, M H; Dickhoff, W H; Dussan, H; Waldecker, S J

    2013-01-01

    A comprehensive description of all single-particle properties associated with the nucleus ${}^{40}$Ca has been generated by employing a nonlocal dispersive optical potential capable of simultaneously reproducing all relevant data above and below the Fermi energy. We gather all relevant functional forms and the numerical values of the parameters in this contribution.

  2. Theoretical model for a Faraday anomalous dispersion optical filter

    Science.gov (United States)

    Yin, B.; Shay, T. M.

    1991-01-01

    A model for the Faraday anomalous dispersion optical filter is presented. The model predicts a bandwidth of 0.6 GHz and a transmission peak of 0.98 for a filter operating on the Cs (D2) line. The model includes hyperfine effects and is valid for arbitrary magnetic fields.

  3. Inverse design of dispersion compensating optical fiber using topology optimization

    DEFF Research Database (Denmark)

    Riishede, Jesper; Sigmund, Ole

    2008-01-01

    We present a new numerical method for designing dispersion compensating optical fibers. The method is based on the solving of the Helmholtz wave equation with a finite-difference modesolver and uses topology optimization combined with a regularization filter for the design of the refractive index...

  4. Optical dispersion of composite particles consisting of millicharged constituents

    CERN Document Server

    Kvam, Audrey K

    2016-01-01

    Composite dark matter (DM) comprised of electrically charged constituents can interact with the electromagnetic field via the particle's dipole moment. This interaction results in a dispersive optical index of refraction for the DM medium. We compute this refractive index for atomic dark matter and more strongly bound systems, modeled via a harmonic oscillator potential. The dispersive nature of the index will result in a time lag between high and low energy photons simultaneously emitted from a distant astrophysical observable. This time lag, due to matter dispersion, could confound potential claims of Lorentz invariance violation (LIV) which can also result in such time lags. We compare the relative size of the two effects and determine that the dispersion due to DM is dwarfed by potential LIV effects for energies below the Planck scale.

  5. Optical dispersion of composite particles consisting of millicharged constituents

    Science.gov (United States)

    Kvam, Audrey K.; Latimer, David C.

    2016-08-01

    Composite dark matter (DM) comprised of electrically charged constituents can interact with the electromagnetic field via the particle's dipole moment. This interaction results in a dispersive optical index of refraction for the DM medium. We compute this refractive index for atomic DM and more strongly bound systems, modeled via a harmonic oscillator potential. The dispersive nature of the index will result in a time lag between high and low energy photons simultaneously emitted from a distant astrophysical observable. This time lag, due to matter dispersion, could confound potential claims of Lorentz invariance violation (LIV) which can also result in such time lags. We compare the relative size of the two effects and determine that the dispersion due to DM is dwarfed by potential LIV effects for energies below the Planck scale.

  6. Experimental arrangement to measure dispersion in optical fiber devices

    Energy Technology Data Exchange (ETDEWEB)

    Armas Rivera, Ivan [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias de la Electronica (Mexico); Beltran Perez, Georgina; Castillo Mixcoatl, Juan; Munoz Aguirre, Severino [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico Matematicas (Mexico); Zaca Moran, Placido, E-mail: ivan_rr1@hotmail.com [Benemerita Universidad Autonoma de Puebla, Fisicoquimica de Materiales ICUAP (Mexico)

    2011-01-01

    Dispersion is a quite important parameter in systems based on optical fiber, especially in pulsed emission lasers, where the temporal width is affected by such parameter. Therefore, it is necessary to consider the dispersion provoked by each component in the cavity. There are various experimental interferometric arrangements to evaluate this parameter. Generally, these systems modify the wavelength to obtain information about the n({lambda}) dependency, which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable and narrow bandwidth laser sources. In the present work, results obtained from an arrangement based on Mach-Zehnder interferometer where one of the arms is the optical fiber under study, while the reference one is air, are presented. In order to determine the n({lambda}) dependency, a wide spectrum light source was used in the wavelength range of interest. The phase information was evaluated from the interferometric signal measured by an optical spectrum analyzer.

  7. Holographic analysis of dispersive pupils in space--time optics

    Energy Technology Data Exchange (ETDEWEB)

    Calatroni, J.; Vienot, J.C.

    1981-06-01

    Extension of space--time optics to objects whose transparency is a function of the temporal frequency v = c/lambda is examined. Considering the effects of such stationary pupils on white light waves, they are called temporal pupils. It is shown that simultaneous encoding both in the space and time frequency domains is required to record pupil parameters. The space-time impulse response and transfer functions are calculated for a dispersive nonabsorbent material. An experimental method providing holographic recording of the dispersion curve of any transparent material is presented.

  8. Total longitudinal momentum in a dispersive optical waveguide.

    Science.gov (United States)

    Yu, Jianhui; Chen, Chunyan; Zhai, Yanfang; Chen, Zhe; Zhang, Jun; Wu, Lijun; Huang, Furong; Xiao, Yi

    2011-12-01

    Using the Lorentz force law, we derived simpler expressions for the total longitudinal (conserved) momentum and the mechanical momentums associated with an optical pulse propagating along a dispersive optical waveguide. These expressions can be applied to an arbitrary non-absorptive optical waveguide having continuous translational symmetry. Our simulation using finite difference time domain (FDTD) method verified that the total momentum formula is valid in a two-dimensional infinite waveguide. We studied the conservation of the total momentum and the transfer of the momentum to the waveguide for the case when an optical pulse travels from a finite waveguide to vacuum. We found that neither the Abraham nor the Minkowski momentum expression for an electromagnetic wave in a waveguide represents the complete total (conserved) momentum. Only the total momentum as we derived for a mode propagating in a dispersive optical waveguides is the 'true' conserved momentum. This total momentum can be expressed as PTot = -U Die/(vg) + neff (U/c). It has three contributions: (1) the Abraham momentum; (2) the momentum from the Abraham force, which equals to the difference between the Abraham momentum and the Minkowski momentum; and (3) the momentum from the dipole force which can be expressed as -UDie/vg. The last two contributions constitute the mechanical momentum. Compared with FDTD-Lorentz-force method, the presently derived total momentum formula provides a better method in terms of analyzing the permanent transfer of optical momentum to a waveguide.

  9. Ultratransparent Media and Transformation Optics with Shifted Spatial Dispersions

    Science.gov (United States)

    Luo, Jie; Yang, Yuting; Yao, Zhongqi; Lu, Weixin; Hou, Bo; Hang, Zhi Hong; Chan, C. T.; Lai, Yun

    2016-11-01

    By using pure dielectric photonic crystals, we demonstrate the realization of ultratransparent media, which allow near 100% transmission of light for all incident angles and create aberration-free virtual images. The ultratransparency effect is well explained by spatially dispersive effective medium theory for photonic crystals, and verified by both simulations and proof-of-principle microwave experiments. Designed with shifted elliptical equal frequency contours, such ultratransparent media not only provide a low-loss and feasible platform for transformation optics devices at optical frequencies, but also enable new freedom for phase manipulation beyond the local medium framework.

  10. Dispersion design of all-normal dispersive microstructured optical fibers for coherent supercontinuum generation

    Science.gov (United States)

    Hartung, Alexander; Heidt, Alexander M.; Bartelt, Hartmut

    2011-05-01

    Recently, the generation of coherent, octave-spanning, and recompressible supercontinuum (SC) light has been demonstrated in optical fibers with all-normal group velocity dispersion (GVD) behavior by femtosecond pumping. In the normal dispersion regime, soliton dynamics are suppressed and the SC generation process is mainly due to self-phase modulation and optical wave breaking. This makes such white light sources suitable for time-resolved applications. The broadest spectra can be obtained when the pump wavelength equals the wavelength of maximum all-normal GVD. Therefore each available pump wavelength requires a specifically designed optical fiber with suitable GVD to unfold its full power. We investigate the possibilities to shift the all-normal maximum dispersion wavelength in microstructured optical fibers from the near infra red (NIR) to the ultra violet (UV). In general, a submicron guiding fiber core surrounded by a holey region is required to overcome the material dispersion of silica. Photonic crystal fibers (PCFs) with a hexagonal array of holes as well as suspended core fibers are simulated for this purpose over a wide field of parameters. The PCFs are varied concerning their air hole diameter and pitch and the suspended core fibers are varied concerning the number of supporting walls and the wall width. We show that these two fiber types complement each other well in their possible wavelength regions for allnormal GVD. While the PCFs are suitable for obtaining a maximum all-normal GVD in the NIR, suspended core fibers are well applicable in the visible wavelength range.

  11. All-optical observation and reconstruction of spin wave dispersion

    Science.gov (United States)

    Hashimoto, Yusuke; Daimon, Shunsuke; Iguchi, Ryo; Oikawa, Yasuyuki; Shen, Ka; Sato, Koji; Bossini, Davide; Tabuchi, Yutaka; Satoh, Takuya; Hillebrands, Burkard; Bauer, Gerrit E. W.; Johansen, Tom H.; Kirilyuk, Andrei; Rasing, Theo; Saitoh, Eiji

    2017-06-01

    To know the properties of a particle or a wave, one should measure how its energy changes with its momentum. The relation between them is called the dispersion relation, which encodes essential information of the kinetics. In a magnet, the wave motion of atomic spins serves as an elementary excitation, called a spin wave, and behaves like a fictitious particle. Although the dispersion relation of spin waves governs many of the magnetic properties, observation of their entire dispersion is one of the challenges today. Spin waves whose dispersion is dominated by magnetostatic interaction are called pure-magnetostatic waves, which are still missing despite of their practical importance. Here, we report observation of the band dispersion relation of pure-magnetostatic waves by developing a table-top all-optical spectroscopy named spin-wave tomography. The result unmasks characteristics of pure-magnetostatic waves. We also demonstrate time-resolved measurements, which reveal coherent energy transfer between spin waves and lattice vibrations.

  12. Polarization mode dispersion in optical fiber transmission systems

    Science.gov (United States)

    Cameron, John Charles

    The birefringence of optical fibers causes pulse broadening in fiber-optic communication systems. This phenomenon is known as polarization mode dispersion (PMD). PMD is one of the most important limiting factors for high capacity fiber-optic systems. A number of aspects of PMD are examined in this thesis. In Chapter 2 an expression is derived for the probability density function of the pulse broadening due to first-order PMD. This result is used to obtain an expression for the system limitation due to PMD. The birefringence of optical fibers is commonly simulated with the waveplate model. In Chapter 3 two standard versions of the waveplate model are introduced. In addition, a novel waveplate model is proposed. The characteristics of the three versions of the waveplate model are examined to confirm their suitability for use in subsequent chapters of the thesis. Simulations with the waveplate model are performed in Chapter 4 for three purposes: (1) to determine the impact of chromatic dispersion on the system limitation due to PMD, (2) to examine the effectiveness of three different PMD compensation techniques in the presence of chromatic dispersion, and (3) to examine the interaction of second-order chromatic dispersion with PMD. The simulations in Chapter 4 reveal that it is possible with one compensation technique to have output pulses that are narrower than the input pulses. In Chapter 5, this anomalous pulse narrowing is demonstrated analytically for a simple model of PMD and through experiment. It is also shown that this pulse narrowing can be explained as an interference phenomenon. Chapter 6 presents measurements of PMD and state of polarization on installed optical fibers. The PMD coefficients of 122 fibers are presented and the results are analyzed in terms of the age of the fibers and the type of cabling. Measurements of the time evolution of PMD and state of polarization are presented for fibers installed in both buried and aerial cables. The uncertainty

  13. Dispersive optical nonlinearities in an EIT-Rydberg medium

    CERN Document Server

    Stanojevic, Jovica; Bimbard, Erwan; Ourjoumtsev, Alexei; Grangier, Philippe

    2013-01-01

    We investigate dispersive optical nonlinearities that arise from Rydberg excitation blockade in cold Rydberg gases. We consider a two-photon transition scheme and study the non-linear response to a weak optical probe in presence of a strong control beam. For very low probe fields, the dominant nonlinearities are of the third order and they can be exactly evaluated in a steady state regime. In a more general case, the change in average atomic populations and coherences due to Rydberg interactions can be characterized by properly defined scaling parameters, which are generally complex numbers but in certain situations take the usual meaning of the number of atoms in a blockade sphere. They can be used in a simple "universal scaling" formula to determine the dispersive optical nonlinearity of the medium. We also develop a novel technique to account for the Rydberg interaction effects, by simplifying the treatment of nonlocal interaction terms, the so-called collisional integrals. We find algebraic relations that...

  14. Optical dispersive shock waves in defocusing colloidal media

    Science.gov (United States)

    An, X.; Marchant, T. R.; Smyth, N. F.

    2017-03-01

    The propagation of an optical dispersive shock wave, generated from a jump discontinuity in light intensity, in a defocusing colloidal medium is analysed. The equations governing nonlinear light propagation in a colloidal medium consist of a nonlinear Schrödinger equation for the beam and an algebraic equation for the medium response. In the limit of low light intensity, these equations reduce to a perturbed higher order nonlinear Schrödinger equation. Solutions for the leading and trailing edges of the colloidal dispersive shock wave are found using modulation theory. This is done for both the perturbed nonlinear Schrödinger equation and the full colloid equations for arbitrary light intensity. These results are compared with numerical solutions of the colloid equations.

  15. Modulational instability in dispersion-kicked optical fibers

    CERN Document Server

    Nodari, S Rota; Dujardin, G; Kudlinski, A; Mussot, A; Trillo, S; De Bièvre, S

    2015-01-01

    We study, both theoretically and experimentally, modulational instability in optical fibers that have a longitudinal evolution of their dispersion in the form of a Dirac delta comb. By means of Floquet theory, we obtain an exact expression for the position of the gain bands, and we provide simple analytical estimates of the gain and of the bandwidths of those sidebands. An experimental validation of those results has been realized in several microstructured fibers specifically manufactured for that purpose. The dispersion landscape of those fibers is a comb of Gaussian pulses having widths much shorter than the period, which therefore approximate the ideal Dirac comb. Experimental spontaneous MI spectra recorded under quasi continuous wave excitation are in good agreement with the theory and with numerical simulations based on the generalized nonlinear Schr\\"odinger equation.

  16. Optical gyroscope with controllable dispersion in four wave mixing regime.

    Science.gov (United States)

    Mikhailov, Eugeniy; Wolfe, Owen; Du, Shuangli; Rochester, Simon; Budker, Dmitry; Novikova, Irina

    2016-05-01

    We present our work towards realization of the fast-light gyroscope prototype, in which the sensitivity enhancement (compared to a regular laser gyroscopes) is achieved by adjusting the intra-cavity dispersion. We discuss schematics and underlying nonlinear effects leading to the negative dispersion in Rb vapor: level structure, optically addressed transitions, and configuration of the resonant cavity. We investigate dependence of the pulling factor (i.e., the ratio of the lasing frequency shift with the change of the cavity length to the equivalent resonance frequency shift in the empty cavity) on pump lasers detunings, power, and density of the atomic vapor. The observation of the pulling factor exceeding unity implies the gyroscope sensitivity improvement over the regular system This work is supported by Naval Air Warfare Center STTR program N68335-11-C-0428.

  17. Femtosecond parabolic pulse shaping in normally dispersive optical fibers.

    Science.gov (United States)

    Sukhoivanov, Igor A; Iakushev, Sergii O; Shulika, Oleksiy V; Díez, Antonio; Andrés, Miguel

    2013-07-29

    Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initial pulse duration, chirp and energy. Applicability of different fibers for femtosecond pulse shaping is analyzed. Recommendation for shortest parabolic pulse formation is made based on the analysis presented.

  18. Improved fiber nonlinearity mitigation in dispersion managed optical OFDM links

    Science.gov (United States)

    Tamilarasan, Ilavarasan; Saminathan, Brindha; Murugappan, Meenakshi

    2017-02-01

    Fiber nonlinearity is seen as a capacity limiting factor in OFDM based dispersion managed links since the Four Wave Mixing effects become enhanced due to the high PAPR. In this paper, the authors have compared the linear and nonlinear PAPR reduction techniques for fiber nonlinearity mitigation in OFDM based dispersion managed links. In the existing optical systems, linear transform techniques such as SLM and PTS have been implemented to reduce nonlinear effects. In the proposed study, superior performance of the L2-by-3 nonlinear transform technique is demonstrated for PAPR reduction to mitigate fiber nonlinearities. The performance evaluation is carried out by interfacing multiple simulators. The results of both linear and nonlinear transform techniques have been compared and the results show that nonlinear transform technique outperforms the linear transform in terms of nonlinearity mitigation and improved BER performance.

  19. Chromatic and Dispersive Effects in Nonlinear Integrable Optics

    CERN Document Server

    Webb, Stephen D; Valishev, Alexander; Nagaitsev, Sergei N; Danilov, Viatcheslav V

    2015-01-01

    Proton accumulator rings and other circular hadron accelerators are susceptible to intensity-driven parametric instabilities because the zero-current charged particle dynamics are characterized by a single tune. Landau damping can suppress these instabilities, which requires energy spread in the beam or introducing nonlinear magnets such as octupoles. However, this approach reduces dynamic aperture. Nonlinear integrable optics can suppress parametric instabilities independent of energy spread in the distribution, while preserving the dynamic aperture. This novel approach promises to reduce particle losses and enable order-of-magnitude increases in beam intensity. In this paper we present results, obtained using the Lie operator formalism, on how chromaticity and dispersion affect particle orbits in integrable optics. We conclude that chromaticity in general breaks the integrability, unless the vertical and horizontal chromaticities are equal. Because of this, the chromaticity correcting magnets can be weaker ...

  20. Slow light, induced dispersion, enhanced nonlinearity, and optical solitons in a resonator-array waveguide.

    Science.gov (United States)

    E Heebner, John; Boyd, Robert W; Park, Q-Han

    2002-03-01

    We describe an optical transmission line that consists of an array of wavelength-scale optical disk resonators coupled to an optical waveguide. Such a structure leads to exotic optical characteristics, including ultraslow group velocities of propagation, enhanced optical nonlinearities, and large dispersion with a controllable magnitude and sign. This device supports soliton propagation, which can be described by a generalized nonlinear Schrodinger equation.

  1. Lateral atlantoaxial joint arthrography in atlantoaxial rotatory fixation.

    Science.gov (United States)

    Hosono, Noboru; Yonenobu, Kazuo; Tada, Koichi; Yoshikawa, Hideki

    2003-04-01

    There has been much debate about the pathogenesis of atlantoaxial rotatory fixation. Intraarticular abnormality has not been well documented thus far. This is the first case of chronic atlantoaxial rotatory fixation in which atlantoaxial joints were examined by consecutive arthrography. A 7-year-old girl was diagnosed with atlantoaxial rotatory fixation on a three-dimensional CT scan. Arthrography of the lateral atlantoaxial joints indicated a rupture of the joint capsule on the dislocated side at first, followed by a successful repair after 5 weeks' immobilization with a halo apparatus. Because torticollis recurred after taking off the halo vest, we performed surgery in which severe adhesion of the cartilage surface of facet joint was noted on the undislocated side and release of the adhesion was needed to mobilize the atlas. Atlantoaxial arthrodesis by screw fixation facilitated a solid fusion of the segment.

  2. Optical Momentum, Spin, and Angular Momentum in Dispersive Media

    Science.gov (United States)

    Bliokh, Konstantin Y.; Bekshaev, Aleksandr Y.; Nori, Franco

    2017-08-01

    We examine the momentum, spin, and orbital angular momentum of structured monochromatic optical fields in dispersive inhomogeneous isotropic media. There are two bifurcations in this general problem: the Abraham-Minkowski dilemma and the kinetic (Poynting-like) versus canonical (spin-orbital) pictures. We show that the kinetic Abraham momentum describes the energy flux and group velocity of the wave in the medium. At the same time, we introduce novel canonical Minkowski-type momentum, spin, and orbital angular momentum densities of the field. These quantities exhibit fairly natural forms, analogous to the Brillouin energy density, as well as multiple advantages as compared with previously considered formalisms. As an example, we apply this general theory to inhomogeneous surface plasmon-polariton (SPP) waves at a metal-vacuum interface and show that SPPs carry a "supermomentum," proportional to the wave vector kp>ω /c , and a transverse spin, which can change its sign depending on the frequency ω .

  3. First-Order-Like Transition for Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HE Ying; ZHU Shi-Qun

    2003-01-01

    The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation is applied to obtain the steady state distribution (SSD) when either the intensity or phase fluctuations of the incident field are included in the system. For intensity fluctuations only, the curve of SSD is changed from single extreme to two extremes, and then to three extremes. The colored nature of the noise can reduce the fluctuation in the system. However, for phase fluctuations only, the FOLT is mainly induced by the colored nature of the noise. The curve of SSD is changed from single extreme to three extremes directly. There is no FOLT existing for white noise.

  4. Novel Nanocomposite Optical Plastics: Dispersion of Titanium in Polyacrylates

    Directory of Open Access Journals (Sweden)

    Gunjan Suri

    2010-01-01

    Full Text Available Polyacrylates have become the preferred materials for optical applications replacing the conventionally used glass due to their superior optical clarity. The major disadvantage with polyacrylates is their low (1.40–1.50 refractive index besides their poor impact resistance. The improvements in refractive index as well as mechanical properties can be achieved by way of incorporation of metals or metal compounds in the matrix. A novel methodology for the incorporation of high refractive index metals into low refractive index polymeric materials to improve the refractive index and impact resistance of the latter has been developed. With the in-situ formation of nanoparticles of TiO2, the refractive index of polyacrylates improved from 1.45 to 1.53 and the Abbe number increased from 40 to 57. One of the interesting dimension of this study pertains to the possibility of tailor-making of the two key optical properties of materials by way of varying the amount of TiO2 being formed in-situ. Thermal stability and impact resistance of nano dispersed (4.3% by wt. of Ti polyacrylates are found to be better than the neat polyacrylates. Moreover, TiO2-containing polyacrylate is of light weight. TEM, SEM, and IR analysis confirms the in-situ formation of nanoparticles of TiO2. Gamma irradiation has been used as an eco-friendly technique for polymerization. The developed compositions can be cast polymerized into clear and bubble free material for optical applications.

  5. Ultra-Short Pulse Tracking by Using Wavelength Dispersion for a Short-Time Optical Buffer

    Institute of Scientific and Technical Information of China (English)

    Tsuyoshi; Konishi; Hideaki; Furukawa; Kousuke; Asano; Kazuyoshi; Itoh

    2003-01-01

    To synchronize a control signal with a packet signal in response to changing timing jitter, we investigate ultra-short pulse tracking by using wavelength dispersion for a short-time optical buffer in an optical router.

  6. Quantum and classical optics of dispersive and absorptive structured media

    Science.gov (United States)

    Bhat, Navin Andrew Rama

    This thesis presents a Hamiltonian formulation of the electromagnetic fields in structured (inhomogeneous) media of arbitrary dimensionality, with arbitrary material dispersion and absorption consistent with causality. The method is based on an identification of the photonic component of the polariton modes of the system. Although the medium degrees of freedom are introduced in an oscillator model, only the macroscopic response of the medium appears in the derived eigenvalue equation for the polaritons. For both the discrete transparent-regime spectrum and the continuous absorptive-regime spectrum, standard codes for photonic modes in nonabsorptive systems can easily be leveraged to calculate polariton modes. Two applications of the theory are presented: pulse propagation and spontaneous parametric down-conversion (SPDC). In the propagation study, the dynamics of the nonfluctuating part of a classical-like pulse are expressed in terms of a Schrodinger equation for a polariton effective field. The complex propagation parameters of that equation can be obtained from the same generalized dispersion surfaces typically used while neglecting absorption, without incurring additional computational complexity. As an example I characterize optical pulse propagation in an Au/MgF 2 metallodielectric stack, using the empirical response function, and elucidate the various roles of Bragg scattering, interband absorption and field expulsion. Further, I derive the Beer coefficient in causal structured media. The SPDC calculation is rigorous, captures the full 3D physics, and properly incorporates linear dispersion. I obtain an expression for the down-converted state, quantify pair-production properties, and characterize the scaling behavior of the SPDC energy. Dispersion affects the normalization of the polariton modes, and calculations of the down-conversion efficiency that neglect this can be off by 100% or more for common media regardless of geometry if the pump is near the band

  7. Optimizing optical pre-dispersion using transmit DSP for mitigation of Kerr nonlinearities in dispersion managed cables

    Science.gov (United States)

    Hopkins, James; Gaudette, Jamie; Mehta, Priyanth

    2013-10-01

    With the advent of digital signal processing (DSP) in optical transmitters and receivers, the ability to finely tune the ratio of pre and post dispersion compensation can be exploited to best mitigate the nonlinear penalties caused by the Kerr effect. A portion of the nonlinear penalty in optical communication channels has been explained by an increase in peak to average power ratio (PAPR) inherent in highly dispersed signals. The standard approach for minimizing these impairments applies 50% pre dispersion compensation and 50% post dispersion compensation, thereby decreasing average PAPR along the length of the cable, as compared with either 100% pre or post dispersion compensation. In this paper we demonstrate that simply considering the net accumulated dispersion, and applying 50/50 pre/post dispersion is not necessarily the best way to minimize PAPR and subsequent Kerr nonlinearities. Instead, we consider the cumulative dispersion along the entire length of the cable, and, taking into account this additional information, derive an analytic formula for the minimization of PAPR. Alignment with simulation and experimental measurements is presented using a commercially available 100Gb/s dual-polarization binary phase-shift-keying (DP-BPSK) coherent modem, with transmitter and receiver DSP. Measurements are provided from two different 5000km dispersion managed Submarine test-beds, as well as a 3800km terrestrial test-bed with a mixture of SMF-28 and TWRS optical fiber. This method is shown to deviate significantly from the conventional 50/50 method described above, in dispersion managed communications systems, and more closely aligns with results obtained from simulation and data collected from laboratory test-beds.

  8. Dispersion Monitoring techniques in High Bit-rate Optical Communication Systems

    Institute of Scientific and Technical Information of China (English)

    SANG Xin-zhu; YU Chong-xiu; ZHANG Qi; WANG Xu

    2004-01-01

    For the efficient dynamic dispersion compensation, it is essential to monitor the dispersion accurately. The existing main dispersion monitoring techniques in high bit- rate optical communication systems are presented as well as their operating principles and research progress. The advantages and disadvantages of these methods are analyzed and discussed.

  9. A FrFT based method for measuring chromatic dispersion and SPM in optical fibers

    Science.gov (United States)

    Yang, Aiying; Liu, Xiang; Chen, Xiaoyu

    2017-03-01

    A fractional Fourier transformation based method is proposed to blindly estimate the chromatic dispersion and self phase modulation in optical fibers. The experimental results demonstrate that up to 20,000 ps/nm accumulative chromatic dispersion of a fiber link is measured with the error less than 0.8%. If the chromatic dispersion is compensated by multiplying an opposite chromatic dispersion function in frequency domain, the 1st order chirp parameter caused by SPM in an optical fiber communication system can be measured by fractional Fourier transformation based method, i.e. the accumulative SPM of a fiber link can be quantitatively measured. The results of equalizing chromatic dispersion and self phase modulation in an optical fiber communication system demonstrated that the FrFT based method is promising to blindly monitor and equalize the chromatic dispersion and SPM of the fiber link in an optical network with dynamical routing function.

  10. Polarization dependent dispersion and its impact on optical parametric process in high nonlinear microstructure fibre

    Institute of Scientific and Technical Information of China (English)

    Xiao Li; Zhang Wei; Huang Yi-Dong; Peng Jiang-De

    2008-01-01

    High nonlinear microstructure fibre (HNMF) is preferred in nonlinear fibre optics, especially in the applications of optical parametric effects, due to its high optical nonlinear coefficient. However, polarization dependent dispersion will impact the nonlinear optical parametric process in HNMFs. In this paper, modulation instability (MI) method is used to measure the polarization dependent dispersion of a piece of commercial HNMF, including the group velocity dispersion, the dispersion slope, the fourth-order dispersion and group birefringence. It also experimentally demonstrates the impact of the polarization dependent dispersion on the continuous wave supercontinuum (SC) generation. On one axis MI sidebands with symmetric frequency dctunings are generated, while on the other axis with larger MI frequency detuning, SC is generated by soliton self-frequency shift.

  11. Performance evaluation for 160-Gb/s optical phase conjugation systems considering dispersion mapping and third-order dispersion

    Institute of Scientific and Technical Information of China (English)

    Jianqiang Li; Kun Xu; Guangtao Zhou; Jian Wu; Jintong Lin

    2007-01-01

    The impact of third-order dispersion (TOD) is investigated by numerical simulations in 160-Gb/s singlechannel systems incorporated with dispersion mapping and optical phase conjugation (OPC). System performances using retrun-to-zero (RZ) or carrier-suppressed RZ (CSRZ) modulation format are evaluated on the optimized dispersion map. The results indicate that even though TOD has been fully compensated,the intra-channel nonlinearity induced by local TOD would degrade the system performance in nonlinear regime. The scheme with an optimized dispersion map provides a much higher performance and offers a larger tolerance on a variation of pre-compensation. CSRZ modulation format is more robust due to its tradeoff between tolerances on intra-channel nonlinearity and dispersion.

  12. Optical tsunamis: shoaling of shallow water rogue waves in nonlinear fibers with normal dispersion

    CERN Document Server

    Wabnitz, Stefan

    2013-01-01

    In analogy with ocean waves running up towards the beach, shoaling of prechirped optical pulses may occur in the normal group-velocity dispersion regime of optical fibers. We present exact Riemann wave solutions of the optical shallow water equations and show that they agree remarkably well with the numerical solutions of the nonlinear Schr\\"odinger equation, at least up to the point where a vertical pulse front develops. We also reveal that extreme wave events or optical tsunamis may be generated in dispersion tapered fibers in the presence of higher-order dispersion.

  13. The influence of stochastic dispersion on optical soliton system and its suppression

    Institute of Scientific and Technical Information of China (English)

    杨祥林; 温扬敬; 张明德

    1995-01-01

    The influence of stochastic dispersion on an optical soliton communication system is investigated, and the method of reducing this influence is also given. The analysis shows that the existence-of stochastic dispersion results in the arrival time jitter, which is in proportion to the mean square fluctuation of the imaginary component of stochastic dispersion and is related to soliton amplitude and velocity. The influence of stochastic dispersion can be reduced by using filtering method in frequency domain.

  14. Zero Dispersion Optical Fibres for High Data Rate Systems

    Directory of Open Access Journals (Sweden)

    V. V. Rampal

    1981-07-01

    Full Text Available The different dispersion parameters that contribute to the pulse spreading in a single mode fibre are discussed with particular reference to the possibility of reducing the total dispersion to zero and increasing the bandwidth and repeater spacing.

  15. Hollow cathode lamp based Faraday anomalous dispersion optical filter.

    Science.gov (United States)

    Pan, Duo; Xue, Xiaobo; Shang, Haosen; Luo, Bin; Chen, Jingbiao; Guo, Hong

    2016-07-15

    The Faraday anomalous dispersion optical filter (FADOF), which has acquired wide applications, is mainly limited to some gaseous elements and low melting-point metals before, for the restriction of the attainable atomic density. In conventional FADOF systems a high atomic density is usually achieved by thermal equilibrium at the saturated vapor pressure, hence for elements with high melting-points a high temperature is required. To avoid this restriction, we propose a scheme of FADOF based on the hollow cathode lamp (HCL), instead of atomic vapor cells. Experimental results in strontium atoms verified this scheme, where a transmission peak corresponding to the (88)Sr (5s(2))(1)S0 - (5s5p)(1)P1 transition (461 nm) is obtained, with a maximum transmittance of 62.5% and a bandwith of 1.19 GHz. The dependence of transmission on magnetic field and HCL discharge current is also studied. Since the state-of-art commercial HCLs cover about 70 elements, this scheme can greatly expand the applications of FADOFs, and the abundant atomic transitions they provide bring the HCL based FADOFs potential applications for frequency stabilization.

  16. Electrically Controlled Optical Metamaterials Based on Dispersions of Nano-Rods

    Science.gov (United States)

    2011-11-15

    4844 Final Report ELECTRICALLY CONTROLLED OPTICAL METAMATERIALS BASED ON DISPERSIONS OF NANO-RODS Andrii B. Golovin , Jie Xiang, Heung-Shik Park...axis can be supplemented by gradients of the composition. For example, as shown by Golovin et al. [22,46] for isotropic dispersion of Au NRs...Optic. Lett. 2008, 33, 1342-1344. 22. Golovin , A.B.; Lavrentovich, O.D. Electrically reconfigurable optical metamaterial based on colloidal

  17. Compensation of chromatic and polarization mode dispersion in fiber-optic communication lines in microwave signals transmittion.

    Science.gov (United States)

    Ermolaev, A. N.; Krishpents, G. P.; Davydov, V. V.; Vysoczkiy, M. G.

    2016-08-01

    Methods of dispersion compensation in fiber-optic communication lines. A new proposed method of electronic dispersion compensation in the transmission of microwave signals through fiber-optic lines. Represents is proposed the results of experimental studies of this method.

  18. Optical phase conjugation for nonlinearity compensation in WDM PDM 16-QAM transmission over dispersion-compensated and dispersion-uncompensated links

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Sackey, I.; Jazayerifar, M.

    2015-01-01

    Kerr nonlinearity compensation by optical phase conjugation is demonstrated in a WDM PDM 16-QAM system. Improved received signal quality is reported for both dispersion-compensated and dispersion-uncompensated transmission and a comparison with digital backpropagation is provided....

  19. A general numerical solution of dispersion relations for the nuclear optical model

    CERN Document Server

    Capote, R; Quesada, J M; Capote, Roberto; Molina, Alberto; Quesada, Jose Manuel

    2001-01-01

    A general numerical solution of the dispersion integral relation between the real and the imaginary parts of the nuclear optical potential is presented. Fast convergence is achieved by means of the Gauss-Legendre integration method, which offers accuracy, easiness of implementation and generality for dispersive optical model calculations. The use of this numerical integration method in the optical-model parameter search codes allows for a fast and accurate dispersive analysis. PACS number(s): 11.55.Fv, 24.10.Ht, 02.60.Jh

  20. Dispersion flattened single mode optical fiber with large effective area

    Science.gov (United States)

    Babita, Rastogi, Vipul

    2013-06-01

    In this paper we present design of a fiber having ultra-flattened dispersion with large effective area over a wide range of wavelengths. The maximum value of the dispersion and dispersion slope within the spectral range 1450-1600 nm are 1.0 ps/km/nm and 0.05 ps/km/nm2 respectively. Effective mode area within the aforementioned wavelength range varies from 100-295 μm2.

  1. Optical pulse compression using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

    Institute of Scientific and Technical Information of China (English)

    CAO; Wenhua; LIU; Songhao

    2004-01-01

    A novel scheme to compress optical pulses is proposed and demonstrated numerically, which is based on a nonlinear optical loop mirror constructed from dispersion decreasing fiber (DDF). We show that, in contrast to the conventional soliton-effect pulse compression in which compressed pulses are always accompanied by pedestals and frequency chirps owning to nonlinear effects, the proposed scheme can completely suppress pulse pedestals and frequency chirps. Unlike the adiabatic compression technique in which DDF length must increase exponentially with input pulsewidth, the proposed scheme does not require adiabatic condition and therefore can be used to compress long pulses by using reasonable fiber lengths. For input pulses with peak powers higher than a threshold value, the compressed pulses can propagate like fundamental solitons. Furthermore, the scheme is fairly insensitive to small variations in the loop length and is more robust to higher-order nonlinear effects and initial frequency chirps than the adiabatic compression technique.

  2. Dispersion-engineered and highly-nonlinear microstructured polymer optical fibres

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch; Nielsen, Kristian; Hlubina, Petr;

    2009-01-01

    We demonstrate dispersion-engineering of microstructured polymer optical fibres (mPOFs) made of poly(methyl methacrylate) (PMMA). A significant shift of the total dispersion from the material dispersion is confirmed through measurement of the mPOF dispersion using white-light spectral....... To increase the nonlinearity of the mPOFs we investigated doping of PMMA with the highly-nonlinear dye Disperse Red 1. Both doping of a PMMA cane and direct doping of a PMMA mPOF was performed....

  3. Simple Method for Measuring the Zero-Dispersion Wavelength in Optical Fibers

    CERN Document Server

    Droques, Maxime; Kudlinski, Alexandre; Bouwmans, Géraud; Mussot, Arnaud

    2012-01-01

    We propose a very simple method for measuring the zero-dispersion wavelength of an optical fiber as well as the ratio between the third- and fourth-order dispersion terms. The method is based on the four wave mixing process when pumping the fiber in the normal dispersion region, and only requires the measurement of two spectra, provided that a source tunable near the zero-dispersion wavelength is available. We provide an experimental demonstration of the method in a photonic crystal fiber and we show that the measured zero-dispersion wavelength is in good agreement with a low-coherence interferometry measurement.

  4. Dispersion management for two-level optically labeled signals in IP-over-WDM networks 4

    DEFF Research Database (Denmark)

    Chi, Nan; Carlsson, Birger; Holm-Nielsen, Pablo Villanueva;

    2002-01-01

    The transmission characteristics of a two-level optically labeled signal with ASK/DPSK modulation are investigated under varying dispersion management. A limitation of extinction ratio and the resilience of fiber span, compensation ratio, and power level are obtained...

  5. Dispersive and nonlinear effects in high-speed reconfigurable WDM optical fiber communication systems

    Science.gov (United States)

    Yu, Changyuan

    Chromatic dispersion, polarization mode dispersion (PMD) and nonlinear effects are important issues on the physical layer of high-speed reconfigurable WDM optical fiber communication systems. For beyond 10 Gbit/s optical fiber transmission system, it is essential that chromatic dispersion and PMD be well managed by dispersion monitoring and compensation. One the other hand, dispersive and nonlinear effects in optical fiber systems can also be beneficial and has applications on pulse management, all-optical signal processing and network function, which will be essential for high bite-rate optical networks and replacing the expensive optical-electrical-optical (O/E/O) conversion. In this Ph.D. dissertation, we present a detailed research on dispersive and nonlinear effects in high-speed optical communication systems. We have demonstrated: (i) A novel technique for optically compensating the PMD-induced RF power fading that occurs in single-sideband (SSB) subcarrier-multiplexed systems. By aligning the polarization states of the optical carrier and the SSB, RF power fading due to all orders of PMD can be completely compensated. (ii) Chromatic-dispersion-insensitive PMD monitoring by using a narrowband FBG notch filter to recover the RF clock power for 10Gb/s NRZ data, and apply it as a control signal for PMD compensation. (iii) Chirp-free high-speed optical pulse generation with a repetition rate of 160 GHz (which is four times of the frequency of the electrical clock) using a phase modulator and polarization maintaining (PM) fiber. (iv) Polarization-insensitive all-optical wavelength conversion based on four-wave mixing in dispersion-shifted fiber (DSF) with a fiber Bragg grating and a Faraday rotator mirror. (v) Width-tunable optical RZ pulse train generation based on four-wave mixing in highly-nonlinear fiber. By electrically tuning the delay between two pump pulse trains, the pulse-width of a generated pulse train is continuously tuned. (vi) A high-speed all-optical

  6. Modulation Instability in Non-Kerr-like Optical Fibers near the Zero Dispersion Point

    Institute of Scientific and Technical Information of China (English)

    LIU Xiumin; ZHANG Xiaoguang; LIN Ning; ZHANG Tao; YANG Bojun

    2000-01-01

    Modulation instability (MI) in non-Kerr-like optical fiber near the zero dispersion point is analyzed. Taking into account the fourth order dispersion, new regions of MI are found. The action of the self-steepening is not the same for each region of MI and critical modulation frequency.

  7. Er-doped concentric-cores optical fiber for simultaneous amplification and compensation of positive dispersion

    Institute of Scientific and Technical Information of China (English)

    Pramod R. Watekar; M. L. N. Goswami; H. N. Acharya; J. C. Biswas; B. P. Pal

    2004-01-01

    The Er-doped concentric-cores dispersion compensating fiber (EDDCF) has been demonstrated. The rare earth has been doped as a ring around the inner core. We have obtained 14-dB gain at 1550 nm (using the optical fiber network where amplification as well as negative dispersion are necessary.

  8. Joint IQ Skew and Chromatic Dispersion Estimation for Coherent Optical Communication Receivers

    DEFF Research Database (Denmark)

    Medeiros Diniz, Júlio César; Porto da Silva, Edson; Piels, Molly

    2016-01-01

    A low-complexity scanning method for joint estimation of receiver IQ skew and chromatic dispersion is proposed. This method shows less than 1 ps skew error for a 1200-km 32-GBd DP-16QAM optical transmission experiment.......A low-complexity scanning method for joint estimation of receiver IQ skew and chromatic dispersion is proposed. This method shows less than 1 ps skew error for a 1200-km 32-GBd DP-16QAM optical transmission experiment....

  9. On Spacetime Transformation Optics: Temporal and Spatial Dispersion

    CERN Document Server

    Gratus, Jonathan; McCall, Martin W; Thompson, Robert T

    2016-01-01

    The electromagnetic implementation of cloaking, the hiding of objects from sight by diverting and reassembling illuminating electromagnetic fields has now been with us ten years, while the notion of hiding events is now five. Both schemes as initially presented neglected the inevitable dispersion that arises when a designed medium replaces vacuum under transformation. Here we define a transformation design protocol that incorporates both spacetime transformations and dispersive material responses in a natural and rigorous way. We show how this methodology is applied to an event cloak designed to appear as a homogeneous and isotropic but dispersive medium. The consequences for spacetime transformation design in dispersive materials are discussed, and some parameter and bandwidth constraints identified.

  10. Noise analysis in photonic true time delay systems based on broadband optical source and dispersion components.

    Science.gov (United States)

    Xue, Xiaoxiao; Wen, He; Zheng, Xiaoping; Zhang, Hanyi; Guo, Yili; Zhou, Bingkun

    2009-02-01

    The noise in photonic true time delay systems based on broadband optical source and dispersion components is investigated. It is found that the beat noise induced by the optical source begins to dominate and grows far larger than other noise terms quickly, as long as the detected optical power is above some certain value P(thr). When the system dispersion is nonzero, the output carrier-to-noise ratio (CNR) will change periodically with the optical bandwidth due to the noise power increment and the dispersion induced radio frequency signal power degradation. The maximum CNR is the peak value of the first period. For a set of specified system conditions, the P(thr) is calculated to be -21 dBm, and the optimal optical bandwidth is 0.8 nm, at which the maximum CNR is 93.3 dB by considering the noise in a 1 Hz bandwidth. The results are verified experimentally.

  11. Dispersion and optical gradient force from high-order mode coupling between two hyperbolic metamaterial waveguides

    Science.gov (United States)

    Wang, Guanghui; Zhang, Weifeng; Lu, Jiahui; Zhao, Huijun

    2016-08-01

    We analytically study dispersion properties and optical gradient forces of different-order transverse magnetic (TM) modes in two coupled hyperbolic metamaterial waveguides (HMMWs). According to Maxwell's equations, we obtain the dispersion relation of symmetric and antisymmetric modes, and calculate optical gradient forces of different-order modes by using Maxwell stress tensor. Numerical results show that the dispersion properties are dependent on the filling ratio, and the optical gradient forces of high-order TM modes are larger than the fundamental mode when the gap between two HMMWs is very narrow, but they weaken much faster than the case of low-order TM modes with the gap width increasing. In addition, the effects of the dielectric surrounding of waveguides on the coupling effect and optical gradient force are clarified. These properties offer an avenue for various optomechanical applications in optical sensors and actuators.

  12. Vibration of prolate spheroidal shells with shear deformation and rotatory inertia: Axisymmetric case

    Science.gov (United States)

    Hayek, Sabih I.; Boisvert, Jeffrey E.

    2003-11-01

    This paper presents the derivation of the equations for nonaxisymmetric motion of prolate spheroidal shells of constant thickness. The equations include the effect of distributed mechanical surface forces and moments. The shell theory used in this derivation includes three displacements and two thickness shear rotations. Thus, the effects of membrane, bending, shear deformation, and rotatory inertia are included in this theory. The resulting five coupled partial differential equations are self-adjoint and positive definite. The frequency-wave-number spectrum has five branches, two acoustic and three optical branches representing flexural, extensional, torsional, and two thickness shear. For the case of axisymmetric motion, these were computed for various spheroidal shell eccentricities and thickness-to-length ratios for a large number of modes. The axisymmetric dynamic response for damped shells of various eccentricities and thicknesses under point and ring surface forces are presented.

  13. Real-time dispersion-compensated image reconstruction for compressive sensing spectral domain optical coherence tomography.

    Science.gov (United States)

    Xu, Daguang; Huang, Yong; Kang, Jin U

    2014-09-01

    In this work, we propose a novel dispersion compensation method that enables real-time compressive sensing (CS) spectral domain optical coherence tomography (SD OCT) image reconstruction. We show that dispersion compensation can be incorporated into CS SD OCT by multiplying the dispersion-correcting terms by the undersampled spectral data before CS reconstruction. High-quality SD OCT imaging with dispersion compensation was demonstrated at a speed in excess of 70 frames per s using 40% of the spectral measurements required by the well-known Shannon/Nyquist theory. The data processing and image display were performed on a conventional workstation having three graphics processing units.

  14. Tailoring the dispersion behavior of optical nanowires with intercore-cladding lithium niobate thin film.

    Science.gov (United States)

    He, Hairong; Miao, Lili; Jiang, Guobao; Zhao, Chujun; Wen, Shuangchun

    2015-10-19

    The dispersion properties of silica and silicon subwavelength-diameter wires with intercore-cladding uniaxial dielectric lithium niobate thin film has been studied numerically in detail. The waveguide dispersion shifts centered around 1550-nm wavelength have been investigated. It shows that the dispersion of optical nanowires with intercore-cladding lithium niobate thin film is highly sensitive to fiber geometry. Moreover, with applied electric field, considerable dispersion shifts without changing its geometric structure can be obtained. Our work may provide an inroad for developing miniaturized functional optoelectronic devices.

  15. Classical realization of dispersion-canceled, artifact-free, and background-free optical coherence tomography

    CERN Document Server

    Ogawa, Kazuhisa

    2016-01-01

    Quantum-optical coherence tomography (Q-OCT) provides a dispersion-canceled axial-imaging method, but its practical use is limited by the weakness of the light source and by artifacts in the images. A recent study using chirped-pulse interferometry (CPI) has demonstrated dispersion-canceled and artifact-free OCT with a classical system; however, unwanted background signals still remain after removing the artifacts. Here, we propose a classical optical method that realizes dispersion-canceled, artifact-free, and background-free OCT. We employ a time-reversed system for Q-OCT with transform-limited input laser pulses to achieve dispersion-canceled OCT with a classical system. We have also introduced a subtraction method to remove artifacts and background signals. With these methods, we experimentally demonstrated dispersion-canceled, artifact-free, and background-free axial imaging of a coverglass and cross-sectional imaging of the surface of a coin.

  16. Mixtures of 3D disperse systems with nano- and micro-particles: Optical characterization

    Directory of Open Access Journals (Sweden)

    Alexandra G. Bezrukova

    2016-12-01

    Full Text Available Multiparameter analysis of simultaneous optical data for systems of nano- and/or micro-particles (3D disperse systems, dispersions, colloids, ensembles by presentation of system characteristics as N-dimensional vectors of optical parameters (ND-vectors can help to elucidate changes in the state of the particles in systems. In this paper, the application of the ND-vector approach is shown on the examples of dispersion mixtures: a mixture of influenza virus particles with albumin proteins (as a model of dispersions at the process of vaccine production; a mixture of coli bacillus and clay dispersions (as natural water model. This approach can serve as an on-line control platform for the management of technological processes with mixtures.

  17. Improving performance of optical fibre chaotic communication by dispersion compensation techniques

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Zhong; Wang Yun-Cai; Wang An-Bang

    2008-01-01

    This paper numerically investigates the effects of dispersion on optical fibre chaotic communication,and proposes a dispersion compensation scheme to improve the performance of optical fibre chaotic communication system.The obtained results show that the transmitter-receiver synchronization progressively degrades and the signal-to-noise ratio of the recovered message deteriorates as the fibre length increases due to the dispersion accumulation.Two segments of 2.5-km dispersion-compensating fibres are symmetrically placed at both ends of a segment of 245-km nonzero dispersionshifted fibre with low dispersion in one compensation period.The numerical results show that the signal-to-noise ratio of the extracted 1 GHz sinusoidal message is improved from-2.92 dB to 15.38 dB by this dispemion compensation for the transmission distance of 500 km.

  18. Dispersion and optical gradient force from high-order mode coupling between two hyperbolic metamaterial waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanghui, E-mail: gsnuwgh@163.com; Zhang, Weifeng; Lu, Jiahui; Zhao, Huijun

    2016-08-12

    We analytically study dispersion properties and optical gradient forces of different-order transverse magnetic (TM) modes in two coupled hyperbolic metamaterial waveguides (HMMWs). According to Maxwell's equations, we obtain the dispersion relation of symmetric and antisymmetric modes, and calculate optical gradient forces of different-order modes by using Maxwell stress tensor. Numerical results show that the dispersion properties are dependent on the filling ratio, and the optical gradient forces of high-order TM modes are larger than the fundamental mode when the gap between two HMMWs is very narrow, but they weaken much faster than the case of low-order TM modes with the gap width increasing. In addition, the effects of the dielectric surrounding of waveguides on the coupling effect and optical gradient force are clarified. These properties offer an avenue for various optomechanical applications in optical sensors and actuators. - Highlights: • The dependence of dispersion properties in hyperbolic metamaterials on the filling ratio is analyzed. • It is possible that the optical gradient forces of high-order modes are larger than the fundamental mode. • Optical gradient forces of high-order modes weaken much faster than the case of low-order modes. • The influence of the dielectric surrounding on the coupling effect and optical gradient force are clarified.

  19. Body-centered cubic dissipative crystal formation in a dispersive and diffractive optical parametric oscillator.

    Science.gov (United States)

    Tlidi, M; Pieroux, D; Mandel, Paul

    2003-09-15

    We show that coupling diffraction and chromatic dispersion lead to body-centered cubic and hexagonally packed cylinders of dissipative optical crystals in a degenerate optical parametric oscillator. The stabilization of these crystals is a direct consequence of the interaction between the modulational and the quasi-neutral modes.

  20. Two-dimensional dispersive shock waves in dissipative optical media

    CERN Document Server

    Kartashov, Yaroslav V

    2013-01-01

    We study generation of two-dimensional dispersive shock waves and oblique dark solitons upon interaction of tilted plane waves with negative refractive index defects embedded into defocusing material with linear gain and two-photon absorption. Different evolution regimes are encountered including the formation of well-localized disturbances for input tilts below critical one, and generation of extended shock waves containing multiple intensity oscillations in the "upstream" region and gradually vanishing oblique dark solitons in "downstream" region for input tilts exceeding critical one. The generation of stable dispersive shock waves is possible only below certain critical defect strength.

  1. Coded-subcarrier-aided chromatic dispersion monitoring scheme for flexible optical OFDM networks.

    Science.gov (United States)

    Tse, Kam-Hon; Chan, Chun-Kit

    2014-08-11

    A simple coded-subcarrier aided scheme is proposed to perform chromatic dispersion monitoring in flexible optical OFDM networks. A pair of coded label subcarriers is added to both edges of the optical OFDM signal spectrum at the edge transmitter node. Upon reception at any intermediate or the receiver node, chromatic dispersion estimation is performed, via simple direct detection, followed by electronic correlation procedures with the designated code sequences. The feasibility and the performance of the proposed scheme have been experimentally characterized. It provides a cost-effective monitoring solution for the optical OFDM signals across intermediate nodes in flexible OFDM networks.

  2. Supercontinuum Spectra generation in the single-mode optical fibre with Concave dispersion profile

    Institute of Scientific and Technical Information of China (English)

    Xu Wen-Cheng; Gao Jie-Li; Liang Zhan-Qiang; Chen Qiao-Hong; Liu Song-Hao

    2006-01-01

    In this paper,a new method is proposed to generate broad supercontinuum (SC) spectra in the single-mode optical fibre with concave dispersion profile.We numerically simulate pulse evolutions and discuss physics mechanism in detail for SC spectrum generation in the optical fibre with concave dispersion profile.Furthermore,general criteria are presented for specifying the shape of SC spectrum by introducing normalized parameters,which are related to the fibres and the initial pump pulses.The results show that the flat and broad SC spectra are indeed generated in our proposed optical fibre.

  3. Sub-picosecond chirped return-to-zero nonlinear optical pulse propagating in dense dispersion-managed fibre

    Science.gov (United States)

    Guo, Shuqin; Le, Zichun; Quan, Bisheng

    2006-01-01

    By numerical simulation, we show that the fourth-order dispersion (FOD) makes sub-picosecond optical pulse broaden as second-order dispersion (SOD), makes optical pulse oscillate simultaneously as third-order dispersion (TOD). Based on above two reasons, sub-picosecond optical pulse will be widely broaden and lead to emission of continuum radiation during propagation. Here, resemble to two- and third-order dispersion compensation, fourth-order dispersion compensation is also suggested in a dispersion-managed optical fiber link, which is realized by arranging two kinds of fiber with opposite dispersion sign in each compensation cell. For sake of avoiding excessively broadening, ultra short scale dispersion compensation cell is required in ultra high speed optical communication system. In a full dispersion compensation optical fiber system which path average dispersion is zero about SOD, TOD, and FOD, even suffering from affection of high order nonlinear like self-steep effect and self-frequency shift, 200 fs gauss optical pulse can stable propagate over 1000 km with an optimal initial chirp. When space between neighboring optical pulse is only 2 picoseconds corresponding to 500 Gbit/s transmitting capacity, eye diagram is very clarity after 1000 km. The results demonstrate that ultra short scale dispersion compensation including FOD is need and effective in ultra-high speed optical communication.

  4. Magneto-Optic Fiber Gratings Useful for Dynamic Dispersion Management and Tunable Comb Filtering

    Science.gov (United States)

    Wu, Bao-Jian; Lu, Xin; Qiu, Kun

    2010-06-01

    Intelligent control of dispersion management and tunable comb filtering in optical network applications can be performed by using magneto-optic fiber Bragg gratings (MFBGs). When a nonuniform magnetic field is applied to the MFBG with a constant grating period, the resulting grating response is equivalent to that of a conventional chirped grating. Under a linearly nonuniform magnetic field along the grating, a linear dispersion is achieved in the grating bandgap and the maximal dispersion slope can come to 1260 ps/nm2 for a 10-mm-long fiber grating at 1550 nm window. Similarly, a Gaussian-apodizing sampled MFBG is also useful for magnetically tunable comb filtering, with potential application to clock recovery from return-to-zero optical signals and optical carrier tracking.

  5. Finite-difference time-domain-based optical microscopy simulation of dispersive media facilitates the development of optical imaging techniques

    Science.gov (United States)

    Zhang, Di; Capoglu, Ilker; Li, Yue; Cherkezyan, Lusik; Chandler, John; Spicer, Graham; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

    2016-06-01

    Combining finite-difference time-domain (FDTD) methods and modeling of optical microscopy modalities, we previously developed an open-source software package called Angora, which is essentially a "microscope in a computer." However, the samples being simulated were limited to nondispersive media. Since media dispersions are common in biological samples (such as cells with staining and metallic biomarkers), we have further developed a module in Angora to simulate samples having complicated dispersion properties, thereby allowing the synthesis of microscope images of most biological samples. We first describe a method to integrate media dispersion into FDTD, and we validate the corresponding Angora dispersion module by applying Mie theory, as well as by experimentally imaging gold microspheres. Then, we demonstrate how Angora can facilitate the development of optical imaging techniques with a case study.

  6. Dispersal

    Science.gov (United States)

    Clobert, J.; Danchin, E.; Dhondt, A.A.; Nichols, J.D.

    2001-01-01

    The ability of species to migrate and disperse is a trait that has interested ecologists for many years. Now that so many species and ecosystems face major environmental threats from habitat fragmentation and global climate change, the ability of species to adapt to these changes by dispersing, migrating, or moving between patches of habitat can be crucial to ensuring their survival. This book provides a timely and wide-ranging overview of the study of dispersal and incorporates much of the latest research. The causes, mechanisms, and consequences of dispersal at the individual, population, species and community levels are considered. The potential of new techniques and models for studying dispersal, drawn from molecular biology and demography, is also explored. Perspectives and insights are offered from the fields of evolution, conservation biology and genetics. Throughout the book, theoretical approaches are combined with empirical data, and care has been taken to include examples from as wide a range of species as possible.

  7. Simulation-Based Design of a Rotatory SMA Drive

    Science.gov (United States)

    Dilthey, Sascha; Meier, Horst

    2009-08-01

    The design and optimization of a rotatory drive powered by shape memory alloy (SMA) actuators is described in this paper. SMA actuators used in technical applications are parameterized by the use of trial-and-error methods, because there is a lack of computer-aided design tools for this active material. A numerical modeling approach was developed to design and optimize the geometry and the load and heating conditions of SMA actuators in a technical system to achieve a good dynamic and a high reliability. The shape memory effect used in most technical systems is the extrinsic two way effect (2WE). This effect can be simulated with the numerical model which was implemented in MATLAB/SIMULINK. The focus of the model is on the activation behavior of the SMA actuator, which defines its rate of heating and cooling. Different load conditions and various actuator geometries and shapes, e.g. wire or spring actuator, are simulated by the calculation of the energetic balance of the whole system. The numerical model can be used to simulate time variant heating currents in order to obtain an optimal system performance. The model was used to design a rotatory SMA-drive system, which is based on the moving concept of a wave drive gear set. In contrast to the conventional system, which is driven by an electric motor, the SMA drive consists of a strain wave gear and SMA wire actuators that are applied circularly to generate a rotatory movement. Special characteristics of this drive system are a high torque density and a high positioning accuracy.

  8. Long-term sequel of posterolateral rotatory instability of the elbow: a case report

    Directory of Open Access Journals (Sweden)

    Cheng Chun-Ying

    2010-01-01

    Full Text Available Abstract The natural course of untreated posterior lateral rotatory instability of the elbow is unclear. A case of elbow arthrosis with progressing deformity and flexion contracture after an episode of elbow dislocation about 20 years ago presented the possibility the long term outcome of untreated posterior lateral rotatory instability of the elbow.

  9. Optical Dispersion Parameters with Different Orientations for SrLaAlO4 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The different optical dispersion parameters of SrLaAlO4 single crystals have been studied by the transmission andreflection measurements at normal incidence for the three orientations 001, 100 and 101 in the spectral range400 nm~2500 nm.The optical absorption data revealed the existance of allowed indirect and direct transition. Therefractive index has abnormal behaviour in the spectral region 400~900 nm, but has a normal one in the higherwavelength region. The optical dispersion parameters, the single oscillator energy Eo and the dispersion energy Edwere determined and indicated the ionic structure of the material. The high-frequency dielectric constant, the latticedielectric constant and the electronic polarizability were determined by the free carriers and the lattice vibrationmodes. The real dielectric constant e1, the dielectric loss tangent (tanδ), the volume (VELF) and the surface energyloss function (SELF) have also been discussed.

  10. Optical delay of a signal through a dispersive invisibility cloak.

    Science.gov (United States)

    Zhang, Baile; Wu, Bae-Ian; Chen, Hongsheng

    2009-04-13

    We present a full-wave analysis method on the transmission of a Gaussian light pulse through a spherical invisibility cloak with causal dispersions. The spatial energy distribution of the Gaussian light pulse is distorted after the transmission. A volcano-shaped spatial time-delay distribution of the transmitted light pulse is demonstrated as a concrete example in our physical model. Both the time-delay and the energy transport depend on the polarization of light waves. This study helps to provide a complete picture of energy propagation through an invisibility cloak.

  11. Passive Ranging Using a Dispersive Spectrometer and Optical Filters

    Science.gov (United States)

    2012-12-20

    sending a number of light rays , from the same point in the scene, into the optical system. Then it traces them through to find where they hit on the focal...55 Appendix A. MATLAB Code Used... radar . First, since no signal is emitted, a passive sensor is much more difficult to detect, which is especially important on stealth platforms

  12. Raman Based Dispersive Systems for Short Pulse Generation and Optical Signal Processing

    Science.gov (United States)

    Kalyoncu, Salih Kagan

    Spatiotemporal dispersive systems have been widely utilized for nonlinear optics and optical signal processing applications. This thesis is dedicated to the investigation of dispersive and nonlinear properties of optical fibers, temporal dispersion for real time operation and spatially dispersed pulse shaping systems. In particular, this thesis is focused on Raman based dispersive systems based on such promising techniques as dispersion management, photonic time stretching and space-to-wavelength mapping for synchronous pulse generation and all-optical RF arbitrary waveform generation incorporated with mature MEMS technology. The first part of this thesis discusses a novel technique of using dispersion managed system for synchronous first and second order pulsed Raman lasers that can achieve frequency spacing of up to 1000 cm-1, which are widely utilized for CARS microscopy applications. In particular, I focus on analytical and numerical analysis of pulsed stability derived for Raman lasers by using dispersion-managed telecom fibers and pumping at near 1530 nm telecom wavelengths. I show the evolution of the first and second order Stokes signals at the output for different peak pump power and the net anomalous dispersion combinations. I determine the stability condition for dispersion-managed synchronous Raman lasers up to second order. In the second part of the thesis, the noise performance of the amplified time stretched systems is investigated. Amplified time stretched systems enabling real time applications such as high-speed analog-to-digital converters, RF arbitrary waveform generation and dispersive imaging are performance limited by the noise cumulated in the system. In particular, I analyze the noise performance and hence the effective number of bits (ENOB) performance of time stretch ADCs with distributed and lumped amplifications. I estimate that distributed amplification in time stretch system with >10GHz analog bandwidth exhibit up to 16dB higher SNR

  13. Theoretical analyses of resonant frequency shift in anomalous dispersion enhanced resonant optical gyroscopes

    Science.gov (United States)

    Lin, Jian; Liu, Jiaming; Zhang, Hao; Li, Wenxiu; Zhao, Lu; Jin, Junjie; Huang, Anping; Zhang, Xiaofu; Xiao, Zhisong

    2016-12-01

    Rigorous expressions of resonant frequency shift (RFS) in anomalous dispersion enhanced resonant optical gyroscopes (ADEROGs) are deduced without making approximation, which provides a precise theoretical guidance to achieve ultra-sensitive ADEROGs. A refractive index related modification factor is introduced when considering special theory of relativity (STR). We demonstrate that the RFS will not be ”infinitely large” by using critical anomalous dispersion (CAD) and negative modification does not exist, which make the mechanism of anomalous dispersion enhancement clear and coherent. Although step change of RFS will happen when the anomalous dispersion condition varies, the amplification of RFS is limited by attainable variation of refractive index in practice. Moreover, it is shown that the properties of anomalous dispersion will influence not only the amplification of RFS, but also the detection range of ADEROGs.

  14. All-channel tunable optical dispersion compensator based on linear translation of a waveguide grating router.

    Science.gov (United States)

    Sinefeld, David; Ben-Ezra, Shalva; Doerr, Christopher R; Marom, Dan M

    2011-04-15

    We propose and demonstrate a compact tunable optical dispersion compensation (TODC) device with a 100 GHz free spectral range capable of mitigating chromatic dispersion impairments. The TODC is based on longitudinal movement of a waveguide grating router, resulting in chromatic dispersion compensation of ±1000 ps/nm. We employed our TODC device for compensating 42.8 Gbit/sec differential phase-shifting keying signal, transmitted over 50 km fiber with a -2 dB power penalty at 10⁻⁹.

  15. Pulse Compression by Filamentation in Argon with an Acoustic Optical Programmable Dispersive Filter for Predispersion Compensation

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Wei; JIANG Yong-Liang; LENG Yu-Xin; LIU Jun; GE Xiao-Chun; LI Ru-Xin; XU Zhi-Zhan

    2006-01-01

    @@ We have experimentally demonstrated pulses 0.4 mJ in duration smaller than 12 fs with an excellent spatial beam profile by self-guided propagation in argon. The original 52fs pulses from the chirped pulsed amplification laser system are first precompressed to 32 fs by inserting an acoustic optical programmable dispersive filter instrument into the laser system for spectrum reshaping and dispersion compensation, and the pulse spectrum is subsequently broadened by filamentation in an argon cell. By using chirped mirrors for post-dispersion compensation, the pulses are successfully compressed to smaller than 12fs.

  16. Dispersion management for a sub-10-fs, 10 TW optical parametric chirped-pulse amplifier.

    Science.gov (United States)

    Tavella, Franz; Nomura, Yutaka; Veisz, Laszlo; Pervak, Vladimir; Marcinkevicius, Andrius; Krausz, Ferenc

    2007-08-01

    We report the amplification of three-cycle, 8.5 fs optical pulses in a near-infrared noncollinear optical parametric chirped-pulse amplifier (OPCPA) up to energies of 80 mJ. Improved dispersion management in the amplifier by means of a combination of reflection grisms and a chirped-mirror stretcher allowed us to recompress the amplified pulses to within 6% of their Fourier limit. The novel ultrabroad, ultraprecise dispersion control technology presented in this work opens the way to scaling multiterawatt technology to even shorter pulses by optimizing the OPCPA bandwidth.

  17. Spatial ordering and abnormal optical activity of DNA liquid-crystalline dispersion particles

    Science.gov (United States)

    Semenov, S. V.; Yevdokimov, Yu. M.

    2016-12-01

    In our work, we investigate physicochemical and optical properties of double-strand DNA dispersions. The study of these properties is of biological interest, because it allows one to describe the characteristics of certain classes of chromosomes and DNA containing viruses. The package pattern of DNA molecules in the dispersions particles (DP) is examined. The consideration of the DNA liquid-crystalline DP optical activity based on the theory of electromagnetic wave absorption by large molecular aggregates has been performed. The investigation is also focused on various effects induced by the interaction between biological active compounds and DNA in the content of liquid-crystalline DP.

  18. Dispersion and polarization dependence of mobile carrier optical nonlinearities

    Science.gov (United States)

    Rustagi, K. C.

    1984-06-01

    Based on the author's earlier work, it is shown that the proper inclusion of carrier scattering should strongly modify the frequency and polarization dependence of optical nonlinearities due to mobile carriers in semiconductors. When the momentum relaxation is much faster than the energy relaxation, the intensity dependent refractive index is enhanced, the induced birefringence becomes a sharp function of the difference frequency ωa-ωb, and a collision induced stimulated Raman effect becomes important.

  19. Apparatus and Methods Using Highly Optically Dispersive Media

    Science.gov (United States)

    2011-08-02

    of two-beam interferometers , such as, e.g., a Michelson interferometer , a Twyman-Green interferometer , and others known in the art. An alternative...guiding fiber . 20 32. The apparatus of claim 1, wherein the apparatus is a spectroscopic interferometer . 33. The apparatus of claim 1, wherein the...Zhimin et a!. "Enhancing the spectral sensitivity of interferometers using slow-light media". Optics Letters, vol. 32, No. 8, Apr. 15, 2007, pp. 915

  20. Entry Dispersion Analysis for the Hayabusa Spacecraft using Ground Based Optical Observation

    CERN Document Server

    Yamaguchi, T; Yagi, M; Tholen, D J

    2011-01-01

    Hayabusa asteroid explorer successfully released the sample capsule to Australia on June 13, 2010. Since the Earth reentry phase of sample return was critical, many backup plans for predicting the landing location were prepared. This paper investigates the reentry dispersion using ground based optical observation as a backup observation for radiometric observation. Several scenarios are calculated and compared for the reentry phase of the Hayabusa to evaluate the navigation accuracy of the ground-based observation. The optical observation doesn't require any active reaction from a spacecraft, thus these results show that optical observations could be a steady backup strategy even if a spacecraft had some trouble. We also evaluate the landing dispersion of the Hayabusa only with the optical observation.

  1. Electro-Optic Effects in Colloidal Dispersion of Metal Nano-Rods in Dielectric Fluid

    Directory of Open Access Journals (Sweden)

    Oleg D. Lavrentovich

    2011-02-01

    Full Text Available In modern transformation optics, one explores metamaterials with properties that vary from point to point in space and time, suitable for application in devices such as an “optical invisibility cloak” and an “optical black hole”. We propose an approach to construct spatially varying and switchable metamaterials that are based on colloidal dispersions of metal nano-rods (NRs in dielectric fluids, in which dielectrophoretic forces, originating in the electric field gradients, create spatially varying configurations of aligned NRs. The electric field controls orientation and concentration of NRs and thus modulates the optical properties of the medium. Using gold (Au NRs dispersed in toluene, we demonstrate electrically induced change in refractive index on the order of 0.1.

  2. Electro-Optic Effects in Colloidal Dispersion of Metal Nano-Rods in Dielectric Fluid

    Science.gov (United States)

    Golovin, Andrii B.; Xiang, Jie; Park, Heung-Shik; Tortora, Luana; Nastishin, Yuriy A.; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

    2011-01-01

    In modern transformation optics, one explores metamaterials with properties that vary from point to point in space and time, suitable for application in devices such as an “optical invisibility cloak” and an “optical black hole”. We propose an approach to construct spatially varying and switchable metamaterials that are based on colloidal dispersions of metal nano-rods (NRs) in dielectric fluids, in which dielectrophoretic forces, originating in the electric field gradients, create spatially varying configurations of aligned NRs. The electric field controls orientation and concentration of NRs and thus modulates the optical properties of the medium. Using gold (Au) NRs dispersed in toluene, we demonstrate electrically induced change in refractive index on the order of 0.1. PMID:28879997

  3. Management of dispersion, nonlinearity and polarization-dependent effects in high-speed reconfigurable WDM fiber optic communication systems

    Science.gov (United States)

    Luo, Ting

    As optical communications approach more data bandwidth, longer transmission distance, and more reconfigurability, dispersion, nonlinearity and polarization-dependent effects are becoming key issues for future all-optical fiber optic systems and networks. For ≥10 Gbit/s optical fiber transmission systems, it is critical that chromatic dispersion and polarization-mode-dispersion be well monitored and compensated using some type of dispersion monitoring and compensation. On the other hand, dispersive and nonlinear effects in optical fiber systems can also be beneficial and have applications on pulse management, all-optical signal processing and network function, which will be essential for high bite-rate optical networks and replacing the expensive optical-electrical-optical (O/E/O) conversion. In this Ph.D. dissertation, we present a detailed research on dispersion, nonlinearity, and polarization-dependent effects in high-speed optical communication systems. We have demonstrated: (i) A dynamic channel-spacing tunable multi-wavelength Erbium-doped fiber laser; (ii) Chromatic-dispersion-insensitive PMD monitoring by tracking the radio-frequency extracted from the vestigial-sideband; (iii) A method for simultaneous chromatic and polarization-mode dispersions monitoring by adding a frequency-shifted carrier; (iv) Polarization-insensitive optical parametric amplification by depolarizing the pump; (v) All optical chromatic dispersion monitoring potential for ultra-high speed (>40 Gbit/s) optical systems using cross-phase modulation in a highly nonlinear fiber; (vi) A novel fiber-based autocorrelator using polarimetric four-wave mixing effect and a tunable differential-group-delay element; (vii) A simple all-fiber-based autocorrelator by measuring the degree-of-polarization; and (viii) Reduction of pattern dependent data distortion in a stimulated Brillouin scattering based slow light element. These techniques will play key roles in future high-speed dynamic WDM optical

  4. Dispersion of the nonlinear refractive index of optical crystals

    Science.gov (United States)

    Adair, Robert; Chase, L. L.; Payne, Stephen A.

    1992-09-01

    The nonlinear refractive indices of several important optical materials have been measured at the second and third harmonic wavelengths of the Nd laser using nearly degenerate four-wave mixing. Measurements made relative to the nonlinear index of fused silica have the highest accuracy. Absolute measurements were also made using the Raman cross-section of benzene as a nonlinear reference standard. The relative measurements are compared with a despersion model base on parameters fitted to the linear refractive indicies and also to a recently proposed model based on Kramers-Kronig transformation of the calculated, two-band, two-photon loss spectrum.

  5. The optical immersion effect in disperse systems with supercritical components

    Science.gov (United States)

    Zimnyakov, D. A.; Yuvchenko, S. A.; Ushakova, O. V.; Tyagnibedin, D. A.; Bagratashvili, V. N.

    2015-04-01

    The method of optical immersion of randomly inhomogeneous media with porous structures into a supercritical fluid (SCF) is considered. Growth in the fluid density upon isothermal increase in the pressure leads to growth in the refractive index and, accordingly, in diffuse transmission of light through a layer of immersed medium. Experimental data on the small-angle diffuse transmission of a model scattering medium (filter paper, PTFE ribbon) are presented for various SCF pressures. Values of the transport length of laser radiation in these media are recovered as dependent on the SCF refractive index.

  6. Dispersion of optical activity of magnesium sulfite hexahydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dimov, T; Bunzarov, Zh; Iliev, I; Petkova, P; Tzoukrovski, Y, E-mail: dimov@shu-bg.ne

    2010-11-01

    The magnesium sulfite hexahydrate (MgSO{sub 3}.6H{sub 2}O) crystals are unique because they are the only representative (with sodium periodate) of the crystallographic class C{sub 3} (without a center of symmetry). The crystal symmetry suggests presence of nonlinearity, piezo- and pyro-electric properties and gyrotropy as well. Single crystals of MgSO{sub 3}.6H{sub 2}O (pure and doped with Ni, Co and Zn) for the time being are grown only by the original method developed in the Laboratory for Crystal growth at the Faculty of Physics in Sofia University. The first results of optical activity of pure MgSO{sub 3}.6H{sub 2}O and Zn doped MgSO{sub 3}.6H{sub 2}O crystals are described and analyzed in a wide spectral range. The optical activity manifests itself in the direction (0001) as a rotation of the polarization plane.

  7. Measuring the Dispersion Curve of a PMMA-Fibre Optic Cable Using a Dye Laser

    Science.gov (United States)

    Zorba, Serkan; Farah, Constantine; Pant, Ravi

    2010-01-01

    An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

  8. Measuring the Dispersion Curve of a PMMA-Fibre Optic Cable Using a Dye Laser

    Science.gov (United States)

    Zorba, Serkan; Farah, Constantine; Pant, Ravi

    2010-01-01

    An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

  9. Recovering parity-time symmetry in highly dispersive coupled optical waveguides

    Science.gov (United States)

    Nguyen, Ngoc B.; Maier, Stefan A.; Hong, Minghui; Oulton, Rupert F.

    2016-12-01

    Coupled photonic systems satisfying parity-time symmetry (PTS) provide flexibility to engineer the flow of light including non-reciprocal propagation, perfect laser-absorbers, and ultra-fast switching. Achieving the required index profile for an optical system with ideal PTS, i.e. n(x)=n{(-x)}* , has proven to be difficult due to the challenge of controlling gain, loss and material dispersion simultaneously. Consequently, most research has focused on dilute or low gain optical systems where material dispersion is minimal. In this paper, we study a model system of coupled inorganic semiconductor waveguides with potentially high gain (>1500 cm-1) and dispersion. Our analysis makes use of coupled mode theory’s parameters to quantify smooth transitions between PTS phases under imperfect conditions. We find that the detrimental influence of gain-induced dispersion is counteracted and the key features of PTS optical systems are recovered by working with non-identical waveguides and bias pumping of the optical waveguides. Our coupled mode theory results show excellent agreement with numerical solutions, proving the robustness of coupled mode theory in describing various degrees of imperfection in systems with PTS.

  10. Influence of Temperature and Pressure on Dispersion Properties of Nonlinear Single Mode Optical Fibers

    Directory of Open Access Journals (Sweden)

    Mostafa H. Ali, Ahmed E. Elsamahy, Maher A. Farhoud and Taymour A. Hamdalla

    2012-10-01

    Full Text Available Near field distribution, propagation constant and dispersion characteristics of nonlinear single-mode optical fibers have been investigated. Shooting-method technique is used and implemented into a computer code for both profiles of step-index and graded-index fibers. An error function is defined to estimate the discrepancy between the expected electric-field radial derivative at the core-cladding interface and that obtained by numerically integrating the wave equation through the use of Runge-Kutta method. All of the above calculations done under the ocean depth in which the depth will affect the refractive index that have a direct effect on all the optical fiber parameters.KeyWords: Nonlinear refractive index, Normalized propagation constant, Mode delay factor, Material dispersion, Waveguide dispersion.

  11. Dispersion Behavior of Gold-Nanocoated Dielectric Optical Fibers

    Directory of Open Access Journals (Sweden)

    P. K. Choudhury

    2012-01-01

    Full Text Available Using a fairly rigorous approach, gold-nanocoated dielectric optical fibers are treated to evaluate the propagation characteristics corresponding to the transverse electric (TE and hybrid EH modes, as supported by the guides with small and large dimensions. Situations with varying nanocoating thickness are considered for two different operating wavelengths. The results demonstrate a profound effect of the gold nanocoating on the propagation-related features—the number of existing modes decreases with increasing nanolayer thickness. Furthermore, the gold nanolayer also has effects on the modal propagation constants, which become more prominent with the increase in the order of modes. It has been found that, in fiber with smaller dimension, the EH11 mode hardly exhibits any effect due to the variation in existing nanolayer coating corresponding to 850 nm wavelength. Almost similar situations are observed for the TE01 mode in large core fiber operating at 1550 nm wavelength.

  12. Dispersion-modulation by high material loss in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch

    2009-01-01

    -induced dispersion significantly modifies the wavelengths for which there is phase-match. Depending on the pump wavelength, the waveguide disper­sion, and the loss peaks, it is possible for the output spectrum to either be unaffected by the loss-induced dispersion modulation, or to show an in......The influence of strong loss peaks on the dispersion (through the Kramers-Kronig relations) of a nonlinear waveguide is investigated theore­ti­cally. It is found specifically for degenerate four-wave mixing in a poly(methyl methacrylate) microstructured polymer optical fiber that the loss......­crea­se in the efficiency of nonlinear spectral broadening, compared to the ex­pected efficiency when ignoring the loss-induced dispersion modulation....

  13. Focus defect and dispersion mismatch in full-field optical coherence microscopy.

    Science.gov (United States)

    Dubois, Arnaud

    2017-03-20

    Full-field optical coherence microscopy (FFOCM) is an optical technique, based on low-coherence interference microscopy, for tomographic imaging of semi-transparent samples with micrometer-scale spatial resolution. The differences in refractive index between the sample and the immersion medium of the microscope objectives may degrade the FFOCM image quality because of focus defect and optical dispersion mismatch. These phenomena and their consequences are discussed in this theoretical paper. Experimental methods that have been implemented in FFOCM to minimize the adverse effects of these phenomena are summarized and compared.

  14. Dispersion model for optical thin films applicable in wide spectral range

    Science.gov (United States)

    Franta, Daniel; Nečas, David; Ohlídal, Ivan; Giglia, Angelo

    2015-09-01

    In the optics industry thin film systems are used to construct various interference devices such as antireflective coatings, high-reflectance mirrors, beam splitters and filters. The optical characterization of complex optical systems can not be performed by measurements only in the short spectral range in which the interference devices will be employed because the measured data do not contain sufficient information about all relevant parameters of these systems. The characterization of film materials requires the extension of the spectral range of the measurements to the IR region containing phonon absorption and to the UV region containing the electronic excitations. However, this leads to necessity of a dispersion model suitable for the description of the dielectric response in the wide spectral range. Such model must respect the physical conditions following from theory of dispersion, particularly Kramers-Kronig relations and integrability imposed by sum rules. This work presents the construction of a universal dispersion model composed from individual contributions representing both electronic and phonon excitations. The efficiency of presented model is given by the fact that all the contributions are described by analytical expressions. It is shown that the model is suitable for precise modeling of spectral dependencies of optical constants of a broad class of materials used in the optical industry for thin film systems such as MgF2, SiO2, Al2O3, HfO2, Ta2O5 and TiO2 in the spectral range from far IR to vacuum UV.

  15. Optical spectroscopy and velocity dispersions of galaxy clusters from the SPT-SZ survey

    Energy Technology Data Exchange (ETDEWEB)

    Ruel, J.; Bayliss, M. [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States); Bazin, G.; Bocquet, S. [Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München (Germany); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Foley, R. J.; Stalder, B.; Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Aird, K. A. [University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Armstrong, R. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Bautz, M. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Cho, H. M. [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); Clocchiatti, A., E-mail: mbayliss@cfa.harvard.edu [Instituto de Astrofisica, Pontificia Universidad Catolica (Chile); and others

    2014-09-01

    We present optical spectroscopy of galaxies in clusters detected through the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report our own measurements of 61 spectroscopic cluster redshifts, and 48 velocity dispersions each calculated with more than 15 member galaxies. This catalog also includes 19 dispersions of SPT-observed clusters previously reported in the literature. The majority of the clusters in this paper are SPT-discovered; of these, most have been previously reported in other SPT cluster catalogs, and five are reported here as SPT discoveries for the first time. By performing a resampling analysis of galaxy velocities, we find that unbiased velocity dispersions can be obtained from a relatively small number of member galaxies (≲ 30), but with increased systematic scatter. We use this analysis to determine statistical confidence intervals that include the effect of membership selection. We fit scaling relations between the observed cluster velocity dispersions and mass estimates from SZ and X-ray observables. In both cases, the results are consistent with the scaling relation between velocity dispersion and mass expected from dark-matter simulations. We measure a ∼30% log-normal scatter in dispersion at fixed mass, and a ∼10% offset in the normalization of the dispersion-mass relation when compared to the expectation from simulations, which is within the expected level of systematic uncertainty.

  16. Tailoring alphabetical metamaterials in optical frequency: plasmonic coupling, dispersion, and sensing.

    Science.gov (United States)

    Zhang, Jun; Cao, Cuong; Xu, Xinlong; Liow, Chihao; Li, Shuzhou; Tan, Pingheng; Xiong, Qihua

    2014-04-22

    Tailoring optical properties of artificial metamaterials, whose optical properties go beyond the limitations of conventional and naturally occurring materials, is of importance in fundamental research and has led to many important applications such as security imaging, invisible cloak, negative refraction, ultrasensitive sensing, and transformable and switchable optics. Herein, by precisely controlling the size, symmetry, and topology of alphabetical metamaterials with U, S, Y, H, U-bar, and V shapes, we have obtained highly tunable optical response covering visible-to-infrared (vis-NIR) optical frequency. In addition, we show a detailed study on the physical origin of resonance modes, plasmonic coupling, the dispersion of resonance modes, and the possibility of negative refraction. We have found that all the electronic and magnetic modes follow the dispersion of surface plasmon polaritons; thus, essentially they are electronic- and magnetic-surface-plasmon-polaritons-like (ESPP-like and MSPP-like) modes resulted from diffraction coupling between localized surface plasmon and freely propagating light. On the basis of the fill factor and formula of magnetism permeability, we predict that the alphabetical metamaterials should show the negative refraction capability in visible optical frequency. Furthermore, we have demonstrated the specific ultrasensitive surface enhanced Raman spectroscopy (SERS) sensing of monolayer molecules and femtomolar food contaminants by tuning their resonance to match the laser wavelength, or by tuning the laser wavelength to match the plasmon resonance of metamaterials. Our tunable alphabetical metamaterials provide a generic platform to study the electromagnetic properties of metamaterials and explore the novel applications in optical frequency.

  17. Fibre Optical Parametric Amplification in Defect Bragg Fibres with Zero Dispersion Slow Light Effect

    Institute of Scientific and Technical Information of China (English)

    XIAO Li; ZHANG Wei; HUANG Yi-Dong; PENG Jiang-De; ZHAO Hong; YANG Ke-Wu

    2008-01-01

    Nonfinearity enhancement by slow light effect and strong light confinement in defect Bragg fibres is demonstrated and analysed in applications of fibre optical parametric amplifiers. Broadband low group velocity and zero dispersion as well as the strong light confinement by band gap enhances the nonlinear coefficient up to more than one order than the conventional high nonlinear fibres.Moreover,the zero dispersion wavelength of coupled core mode can be designed arbitrarily,under which the phase-matching bandwidth of the nonlinear process can be extended.

  18. Self-focusing of optical pulses in media with normal dispersion

    DEFF Research Database (Denmark)

    Bergé, L.; Kuznetsov, E.A.; Juul Rasmussen, J.;

    1996-01-01

    propagating in a nonlinear medium with normal dispersion will not collapse to a singularity in the transverse diffraction plane. It is explicitly shown that the pulse spreads out along the ''time-direction'' and ultimately splits up. The analytical results are supported by direct numerical solutions.......The self-focusing of ultra short optical pulses in a nonlinear medium with normal (i.e., negative) group-velocity dispersion is investigated. By using a combination of various techniques like virial-type arguments and self-similar transformations, we obtain strong evidence suggesting that a pulse...

  19. Dispersion effect in optical microscopy systems with a supersphere solid immersion lens

    Institute of Scientific and Technical Information of China (English)

    Zhang Yao-Ju; Zhuang You-Yi

    2009-01-01

    This paper studies the dispersion effect of the supersphere solid immersion lens (SIL) on a near field optical microscopy system by using the vector diffraction theory. Results show that when a real non-monochromatic beam illuminates a supersphere SIL microscopy, the dispersion effect of the SIL has an important influence on the image quality. As the wavelength bandwidth of the non-monochromatic beam increases, the size of the focused spot increases and its intensity decreases in near-field microscopy systems with a supersphere SIL.

  20. Performance Analysis of High-speed Optical Pulse Transmission in Dispersion-managed Nonlinear Birefringent Fiber Using Quantum Well Laser Diode Sources

    Institute of Scientific and Technical Information of China (English)

    YAN Minhui; CHEN Jianping

    2002-01-01

    This paper analyzes the high bit-rate optical pulse trasmission in single mode optical fiber with chromatic dispersion, polarization mode dispersion (small random birefringence) and nonlinearity. Numerical method employed can precisely describe their interactive effect on transmission performance. Different dispersion maps and the related performance are analysed. Various simulation results and discussion are given. The results show that chromatic dispersion compensation should be carefully designed. Appropriate dispersion management can also alleviate the effect of polarization mode dispersion.

  1. Optical Spectroscopy and Velocity Dispersions of Galaxy Clusters from the SPT-SZ Survey

    CERN Document Server

    Ruel, J; Bayliss, M; Brodwin, M; Foley, R J; Stalder, B; Aird, K A; Armstrong, R; Ashby, M L N; Bautz, M; Benson, B A; Bleem, L E; Bocquet, S; Carlstrom, J E; Chang, C L; Chapman, S C; Cho, H M; Clocchiatti, A; Crawford, T M; Crites, A T; de Haan, T; Desai, S; Dobbs, M A; Dudley, J P; Forman, W R; George, E M; Gladders, M D; Gonzalez, A H; Halverson, N W; Harrington, N L; High, F W; Holder, G P; Holzapfel, W L; Hrubes, J D; Jones, C; Joy, M; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Liu, J; Lueker, M; Luong-Van, D; Mantz, A; Marrone, D P; McDonald, M; McMahon, J J; Mehl, J; Meyer, S S; Mocanu, L; Mohr, J J; Montroy, T E; Murray, S S; Natoli, T; Nurgaliev, D; Padin, S; Plagge, T; Pryke, C; Reichardt, C L; Rest, A; Ruhl, J E; Saliwanchik, B R; Saro, A; Sayre, J T; Schaffer, K K; Shaw, L; Shirokoff, E; Song, J; Šuhada, R; Spieler, H G; Stanford, S A; Staniszewski, Z; Stark, A A; Story, K; Stubbs, C W; van Engelen, A; Vanderlinde, K; Vieira, J D; Vikhlinin, A; Williamson, R; Zahn, O; Zenteno, A

    2013-01-01

    We present optical spectroscopy of galaxies in clusters detected through the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report our own measurements of $61$ spectroscopic cluster redshifts, and $48$ velocity dispersions each calculated with more than $15$ member galaxies. This catalog also includes $19$ dispersions of SPT-observed clusters previously reported in the literature. The majority of the clusters in this paper are SPT-discovered; of these, most have been previously reported in other SPT cluster catalogs, and five are reported here as SPT discoveries for the first time. By performing a resampling analysis of galaxy velocities, we find that unbiased velocity dispersions can be obtained from a relatively small number of member galaxies ($\\lesssim 30$), but with increased systematic scatter. We use this analysis to determine statistical confidence intervals that include the effect of membership selection. We fit scaling relations between the observed cluster velocity dispersio...

  2. Optical properties of the glass composites with nanofilms: the relationship to the dispersed phase of sol

    Directory of Open Access Journals (Sweden)

    A.B. Atkarskaya

    2015-03-01

    Full Text Available It has been found that the particles size, volume fraction of the film-forming sol disperse phase, the pack-density of the particles in the layer, affect the optical properties of nanodimensional films and composites consisting of a glass substrate coated with the surface film. The threshold energy density of the laser ablation destruction of the films being components of the composites also depends largely on the state of the sol dispersed phase. This value needed for the ablation under the laser radiation with nanosecond pulse duration was found to increase with the dispersed phase particles pack-density in the layer. Moreover, this value increased with the particle size and decreased as the fraction by volume of that phase and particles pack-density rose when using microsecond pulse duration. These relationships are due to low thickness and density of the nanofilm, and as a result the laser beam interacted practically with the dense glass substrate.

  3. Evolution of optical pulses in the presence of third-order dispersion

    Indian Academy of Sciences (India)

    Debabrata Pal; S K Golam Ali; B Talukdar

    2009-06-01

    We model the propagation of femtosecond pulses through optical fibres by a nonlinear Schrödinger (NLS) equation involving a perturbing term arising due to third-order dispersion in the medium. The perturbative effect of this higher-order dispersion causes the usual NLS soliton to emit a radiation field. As a result, the given initial pulse propagating through the fibre exhibits nonsolitonic behaviour. We make use of a variational method to demonstrate how an initial pulse by the interaction with the emitted radiation can evolve into a soliton. We also demonstrate that the effect of interaction between the initial pulse and radiation field can be accounted for by including, in the evolution equation, terms associated with self-steepening and stimulated Raman scattering that characterize the optical medium.

  4. Observation and measurement of interaction-induced dispersive optical nonlinearities in an ensemble of cold rydberg atoms

    DEFF Research Database (Denmark)

    Parigi, V.; Bimbard, E.; Stanojevic, J.

    2012-01-01

    We observe and measure dispersive optical nonlinearities in an ensemble of cold Rydberg atoms placed inside an optical cavity. The experimental results are in agreement with a simple model where the optical nonlinearities are due to the progressive appearance of a Rydberg blockaded volume within ...

  5. Observation and measurement of interaction-induced dispersive optical nonlinearities in an ensemble of cold Rydberg atoms.

    Science.gov (United States)

    Parigi, Valentina; Bimbard, Erwan; Stanojevic, Jovica; Hilliard, Andrew J; Nogrette, Florence; Tualle-Brouri, Rosa; Ourjoumtsev, Alexei; Grangier, Philippe

    2012-12-07

    We observe and measure dispersive optical nonlinearities in an ensemble of cold Rydberg atoms placed inside an optical cavity. The experimental results are in agreement with a simple model where the optical nonlinearities are due to the progressive appearance of a Rydberg blockaded volume within the medium. The measurements allow a direct estimation of the "blockaded fraction" of atoms within the atomic ensemble.

  6. New measurement technique for dispersion characterizing optical fibers using low-coherence spectral interferometry with a Michelson interferometer

    Science.gov (United States)

    Hlubina, Petr

    1999-08-01

    Low-coherence spectral interferometry with channelled spectrum detection, extensively used for dispersion characterizing optical fibers, utilizes the fact that the spectral interference between two modes of an optical fiber shows up at its output as a periodic modulation of the source spectrum with the period dependent on the group optical path difference (OPD) between modes. However, this measurement technique cannot be used to measure intermodal dispersion in the optical fiber for which the period of modulation is too small to be resolved by a spectrometer. We proposed and realized a new measurement technique utilizing a tandem configuration of a dispersive Michelson interferometer and the two-mode optical fiber in which the intermodal spectral interference can be resolved even if a low-resolution spectrometer is used. In the tandem configuration of the dispersive Michelson interferometer and the two-mode optical fiber, the OPD in the Michelson interferometer is adjusted close to the group OPD between modes of the optical fiber so that the low-frequency spectral modulation that can be processed is produced. Using the Fourier transform method in processing the measured spectral modulations and subtracting the effect of the dispersive Michelson interferometer, the intermodal dispersion of the two-mode optical fiber over a limited spectral region has been obtained.

  7. Determination of dispersive optical constants of nanocrystalline CdSe (nc-CdSe) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Kriti; Al-Kabbi, Alaa S.; Saini, G.S.S. [Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh 160014 (India); Tripathi, S.K., E-mail: surya@pu.ac.in [Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh 160014 (India)

    2012-06-15

    Highlights: ► nc-CdSe thin films are prepared by thermal vacuum evaporation technique. ► TEM analysis shows NCs are spherical in shape. ► XRD reveals the hexagonal (wurtzite) crystal structure of nc-CdSe thin films. ► The direct optical bandgap of nc-CdSe is 2.25 eV in contrast to bulk (1.7 eV). ► Dispersion of refractive index is discussed in terms of Wemple–DiDomenico single oscillator model. -- Abstract: The nanocrystalline thin films of CdSe are prepared by thermal evaporation technique at room temperature. These thin films are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). The transmission spectra are recorded in the transmission range 400–3300 nm for nc-CdSe thin films. Transmittance measurements are used to calculate the refractive index (n) and absorption coefficient (α) using Swanepoel's method. The optical band gap (E{sub g}{sup opt}) has been determined from the absorption coefficient values using Tauc's procedure. The optical constants such as extinction coefficient (k), real (ε{sub 1}) and imaginary (ε{sub 2}) dielectric constants, dielectric loss (tan δ), optical conductivity (σ{sub opt}), Urbach energy (E{sub u}) and steepness parameter (σ) are also calculated for nc-CdSe thin films. The normal dispersion of refractive index is described using Wemple–DiDomenico single-oscillator model. Refractive index dispersion is further analysed to calculate lattice dielectric constant (ε{sub L}).

  8. Dispersions of Semiconductor Nanoparticles in Thermotropic Liquid Crystal: From Optical Modification to Assisted Self-Assembly

    OpenAIRE

    Rodarte, Andrea L.

    2014-01-01

    The interaction of semiconducting quantum dot nanoparticles (QDs) within thermotropic liquid crystalline (LC) materials are studied in this thesis. LC materials are ideal for bottom-up organization of nanoparticles as an active matrix that can be externally manipulated via electric or magnetic fields. In addition, the optical properties of QDs can be modified by the surrounding LC resulting in novel devices such as a quantum dot/liquid crystal laser. The first system studies the dispersion of...

  9. Moment method, Higher order dispersion map and other effects in optical pulse propagation

    OpenAIRE

    Mondal, Basanti; Chowdhury, A. Roy.

    2005-01-01

    Analytical and numerical procedures are applied to show that both third and second order dispersion maps can be explicitly constructed and their mutual effects on the optical pulse propagation are analysed. In these connection it is also shown how the other important features such as amplification, intra-channel Raman Scattering(IRS), fibre loss, centre frequency of the pulse spectrum effect the propagation of pulse. Due to the presence of IRS, moment method is adopted which is easily reduced...

  10. Optical glass with tightest refractive index and dispersion tolerances for high-end optical designs

    Science.gov (United States)

    Jedamzik, R.; Reichel, S.; Hartmann, P.

    2014-03-01

    In high end optical designs the quality of the optical system not only depends on the chosen optical glasses but also on the available refractive index and Abbe number tolerances. The primary optical design is based on datasheet values of the refractive index and Abbe number. In general the optical position of the delivered glass will deviate from the catalog values by given tolerances due to production tolerances. Therefore in many cases the final optical design needs to be modified based on real glass data. Tighter refractive index and Abbe number tolerances can greatly reduce this additional amount of work. The refractive index and Abbe number of an optical glass is a function of the chemical composition and the annealing process. Tight refractive index tolerances require not only a close control and high reliability of the melting and fine annealing process but also best possible material data. These data rely on high accuracy measurement and accurate control during mass production. Modern melting and annealing procedure do not only enable tight index tolerances but also a high homogeneity of the optical properties. Recently SCHOTT was able to introduce the tightest available refractive index and Abbe number tolerance available in the market: step 0.5 meaning a refractive index tolerance of +/- 0.0001 and an Abbe number tolerance of +/- 0.1%. This presentation describes how the refractive index depends on the glass composition and annealing process and describes the requirements to get to this tightest refractive index and Abbe number tolerance.

  11. Modeling of dispersion and nonlinear characteristics of tapered photonic crystal fibers for applications in nonlinear optics

    Science.gov (United States)

    Pakarzadeh, H.; Rezaei, S. M.

    2016-01-01

    In this article, we investigate for the first time the dispersion and the nonlinear characteristics of the tapered photonic crystal fibers (PCFs) as a function of length z, via solving the eigenvalue equation of the guided mode using the finite-difference frequency-domain method. Since the structural parameters such as the air-hole diameter and the pitch of the microstructured cladding change along the tapered PCFs, dispersion and nonlinear properties change with the length as well. Therefore, it is important to know the exact behavior of such fiber parameters along z which is necessary for nonlinear optics applications. We simulate the z dependency of the zero-dispersion wavelength, dispersion slope, effective mode area, nonlinear parameter, and the confinement loss along the tapered PCFs and propose useful relations for describing dispersion and nonlinear parameters. The results of this article, which are in a very good agreement with the available experimental data, are important for simulating pulse propagation as well as investigating nonlinear effects such as supercontinuum generation and parametric amplification in tapered PCFs.

  12. Generation of Flat Supercontinuum in a Single-mode Optical Fiber with a Convex Chromatic Dispersion Profile

    Institute of Scientific and Technical Information of China (English)

    XU Yong-zhao; WANG Hong-chen; ZHOU Shou-li

    2009-01-01

    A single-mode optical fiber with a convex chromatic dispersion profile is proposed for generating a flat supercontinuum(SC). The fiber has normal dispersion and the dispersion parameter D(λ,z) is a convex function of wavelengths. It is shown from the numerical results that the chromatic dispersion, the flatness of the dispersion curve and the pump conditions have significant effect on SC generation. A flat and broad SC without strong residual pump component can be obtained when the pump wavelength is set in the vicinity of the wavelength at which the fiber has small normal group-velocity dispersion(GVD) and small dispersion slope. The fiber with a smaller normal GVD, a flatter dispersion profile and a higher nonlinear coefficient are more suitable for broad SC generation.

  13. Evaluating E. coli degradation using a rotatory disk photoreactor

    Directory of Open Access Journals (Sweden)

    Gina María Hincapié Mejía

    2010-04-01

    Full Text Available Degradation of the bacterium E. coli was studied using a rotatory disk photoreactor manufactured in stainless steel to ascertain this photoreaction system’s behaviour in different operating conditions. The photoreactor was equipped with 6 black light bulbs (BLB used as a source of UV light and fitted with 7 removable disks made of common frosted glass impregnated with TiO2 photocatalyzer which were coupled to a rotation system. TiO2 was impregnated on the disks using the sol-gel method varying molar precursor gel ratios. Abrasion resistance, disk adhesion and surface uniformity tests were carried out for selecting the film presenting the best characteristics. Bacterial photodegradation studies were carried out using the following variable parameters: the disks’ rotation speed, radiation intensity and the number of discs which were directly related to the concentration of photo-catalyzer in the system. Up to 64.3% degradation was achieved in 4 hours using 7 disks, low intensity and low rotation speed.

  14. Smart Optical Composite Materials: Dispersions of Metal-Organic Framework@Superparamagnetic Microrods for Switchable Isotropic-Anisotropic Optical Properties.

    Science.gov (United States)

    Mandel, Karl; Granath, Tim; Wehner, Tobias; Rey, Marcel; Stracke, Werner; Vogel, Nicolas; Sextl, Gerhard; Müller-Buschbaum, Klaus

    2017-01-24

    A smart optical composite material with dynamic isotropic and anisotropic optical properties by combination of luminescence and high reflectivity was developed. This combination enables switching between luminescence and angle-dependent reflectivity by changing the applied wavelength of light. The composite is formed as anisotropic core/shell particles by coating superparamagnetic iron oxide-silica microrods with a layer of the luminescent metal-organic framework (MOF) (3)∞[Eu2(BDC)3]·2DMF·2H2O (BDC(2-) = 1,4-benzenedicarboxylate). The composite particles can be rotated by an external magnet. Their anisotropic shape causes changes in the reflectivity and diffraction of light depending on the orientation of the composite particle. These rotation-dependent optical properties are complemented by an isotropic luminescence resulting from the MOF shell. If illuminated by UV light, the particles exhibit isotropic luminescence while the same sample shows anisotropic optical properties when illuminated with visible light. In addition to direct switching, the optical properties can be tailored continuously between isotropic red emission and anisotropic reflection of light if the illuminating light is tuned through fractions of both UV and visible light. The integration and control of light emission modes within a homogeneous particle dispersion marks a smart optical material, addressing fundamental directions for research on switchable multifunctional materials. The material can function as an optic compass or could be used as an optic shutter that can be switched by a magnetic field, e.g., for an intensity control for waveguides in the visible range.

  15. Optical Dispersion, Permittivity Spectrum and Thermal-Lensing Effect in Nickel-Doped Zinc Sulfide Nanoparticles

    Science.gov (United States)

    Abbasi, F.; Koushki, E.; Majles Ara, M. H.; Sahraei, R.

    2017-07-01

    In this paper, Ni-doped ZnS (ZnS:Ni2+) nanoparticles (NPs) have been prepared through a chemical method. The average size of the particle is 45 nm. Thin films of the particles have been prepared by using the spin-coating method. The linear and nonlinear optical properties of Ni-doped ZnS thin films and the colloidal solution of them have been studied widely. Using a precise numerical method, the refractive index curve (dispersion curve), absorption coefficient and optical permittivity of Ni-doped ZnS film have been obtained. Using these values, the absorption coefficient of the colloidal solution of Ni-doped ZnS particles has been simulated and compared with experimental results. Finally, using the z-scan method at low laser irradiation, the thermo-optical effect has been studied and the nonlinear refractive index due to this effect has been reported.

  16. Fast dispersion estimation in coherent optical 16QAM fast OFDM systems.

    Science.gov (United States)

    Zhao, J; Shams, H

    2013-01-28

    Fast channel estimation is crucial to increase the payload efficiency which is of particular importance for optical packet networks. In this paper, we propose a novel least-square based dispersion estimation method in coherent optical fast OFDM (F-OFDM) systems. Additionally, we experimentally demonstrate for the first time a 37.5 Gb/s 16QAM coherent F-OFDM system with 480 km transmission using the proposed scheme. The results show that this method outperforms the conventional channel estimation methods in minimizing the overhead load. A single training symbol can achieve near-optimum channel estimation without any prior information of the transmission distance. This makes optical F-OFDM a very promising scheme for the future burst-mode applications.

  17. Low-coherence spectral interferometry with a Michelson interferometer applied to dispersion measurement of a two-mode optical fiber

    Science.gov (United States)

    Hlubina, Petr

    1999-12-01

    Intermodal dispersion in a two-mode optical fiber can be measured in the spectral domain when the spectral interference between modes at the output of the optical fiber shows up as a periodic modulation of the source spectrum that can be processed. However, this technique cannot be used to measure intermodal dispersion in the two- mode optical fiber when the period of modulation is too small to be resolved by a spectrometer. Consequently, we proposed a new measuring technique utilizing a tandem configuration of a dispersive Michelson interferometer and the two-mode optical fiber in which the spectral interference can be resolved even if a low-resolution spectrometer is used. In the tandem configuration of the Michelson interferometer and the two-mode optical fiber, the optical path difference (OPD) in the Michelson interferometer is adjusted close to the group OPD between modes of the optical fiber so that the low-frequency spectral modulation that can be processed is produced. Using the Fourier transform method in processing the measured spectral modulations and subtracting the effect of the dispersive Michelson interferometer, the feasibility of this technique has successfully been demonstrated in obtaining the intermodal dispersion in the two-model optical fiber.

  18. Length measurement in absolute scale via low-dispersion optical cavity

    Science.gov (United States)

    Pravdova, Lenka; Lesundak, Adam; Smid, Radek; Hrabina, Jan; Rerucha, Simon; Cip, Ondrej

    2016-12-01

    We report on the length measuring instrument with the absolute scale that was based on the combination of an optical frequency comb and a passive optical cavity. The time spacing of short femtosecond pulses, generated by the optical frequency comb, is optically phase locked onto the cavity free spectral range with a derivative spectroscopy technique so that the value of the repetition frequency of the femtosecond laser is tied to and determines the measured displacement. The instantaneous value of the femtosecond pulse train frequency is counted by a frequency counter. This counted value corresponds to the length given by the spacing between the two mirrors of the passive cavity. The phase lock between the femtosecond pulsed beam and the passive cavity is possible due to the low-dispersion of the cavity mirrors, where the silver coating on the mirrors was used to provide the low dispersion for the broadband radiation of the comb. Every reflection on the output mirror feeds a portion of the beam back to the cavity so that the output beam is a result of multiple interfering components. The parameters of the output beam are given not only by the parameters of the mirrors but mainly by the absolute distance between the mirror surfaces. Thus, one cavity mirror can be considered as the reference starting point of the distance to be measured and the other mirror is the measuring probe surveying the unknown distance. The measuring mirror of the experimental setup of the low-dispersion cavity is mounted on a piezoelectric actuator which provides small changes in the cavity length we used to test the length measurement method. For the verification of the measurement accuracy a reference incremental interferometer was integrated into our system so that the displacement of the piezoelectric actuator could be obtained with both measuring methods simultaneously.

  19. Design of a transversal equalizer for electronic dispersion compensation in optical communication links

    Institute of Scientific and Technical Information of China (English)

    GAO Zhen-bin; SHI Yong; WANG Bo; ZENG Xiang-ye

    2011-01-01

    @@ A programmable transversal equalizer for electronic dispersion compensation (EDC) in optical fiber communication systems is developed.Based on the SiGe technology with a cut-off frequency of 80 GHz, the equalizer consists of 6 seriesparallel amplifiers as delay units and 7 Gilbert variable gain amplifiers as taps, which ensure that the equalizer can work at the bit rate of 10 Gb/s.With different tap gains, the forward voltage gain of the transversal equalizer varies, which demonstrates that the equalizer has various filtering characteristics such as low pass filtering, band pass filtering, band reject filtering, and notch filtering, so it can effectively simulate the inverse transfer function of dispersive channels in optical communications, and can be used for compensating the inter-symbol interference and other nonlinear problems caused by dispersion.The equalizer (including pads) occupies an area of 0.40 mm × 1.08 mm, and its total power dissipation is 400 mW with 3.3 V power supply.

  20. Design of a transversal equalizer for electronic dispersion compensation in optical communication links

    Science.gov (United States)

    Gao, Zhen-bin; Shi, Yong; Wang, Bo; Zeng, Xiang-ye

    2011-01-01

    A programmable transversal equalizer for electronic dispersion compensation (EDC) in optical fiber communication systems is developed. Based on the SiGe technology with a cut-off frequency of 80 GHz, the equalizer consists of 6 seriesparallel amplifiers as delay units and 7 Gilbert variable gain amplifiers as taps, which ensure that the equalizer can work at the bit rate of 10 Gb/s. With different tap gains, the forward voltage gain of the transversal equalizer varies, which demonstrates that the equalizer has various filtering characteristics such as low pass filtering, band pass filtering, band reject filtering, and notch filtering, so it can effectively simulate the inverse transfer function of dispersive channels in optical communications, and can be used for compensating the inter-symbol interference and other nonlinear problems caused by dispersion. The equalizer (including pads) occupies an area of 0.40 mm×1.08 mm, and its total power dissipation is 400 mW with 3.3 V power supply.

  1. Compressive sensing with dispersion compensation on non-linear wavenumber sampled spectral domain optical coherence tomography.

    Science.gov (United States)

    Xu, Daguang; Huang, Yong; Kang, Jin U

    2013-01-01

    We propose a novel compressive sensing (CS) method on spectral domain optical coherence tomography (SDOCT). By replacing the widely used uniform discrete Fourier transform (UDFT) matrix with a new sensing matrix which is a modification of the non-uniform discrete Fourier transform (NUDFT) matrix, it is shown that undersampled non-linear wavenumber spectral data can be used directly in the CS reconstruction. Thus k-space grid filling and k-linear mask calibration which were proposed to obtain linear wavenumber sampling from the non-linear wavenumber interferometric spectra in previous studies of CS in SDOCT (CS-SDOCT) are no longer needed. The NUDFT matrix is modified to promote the sparsity of reconstructed A-scans by making them symmetric while preserving the value of the desired half. In addition, we show that dispersion compensation can be implemented by multiplying the frequency-dependent correcting phase directly to the real spectra, eliminating the need for constructing complex component of the real spectra. This enables the incorporation of dispersion compensation into the CS reconstruction by adding the correcting term to the modified NUDFT matrix. With this new sensing matrix, A-scan with dispersion compensation can be reconstructed from undersampled non-linear wavenumber spectral data by CS reconstruction. Experimental results show that proposed method can achieve high quality imaging with dispersion compensation.

  2. Dispersive spherical optical model of neutron scattering from Al27 up to 250 MeV

    CERN Document Server

    Molina, A; Quesada, J M; Lozano, M

    2002-01-01

    A spherical optical model potential (OMP) containing a dispersive term is used to fit the available experimental database of angular distribution and total cross section data for n + Al27 covering the energy range 0.1- 250 MeV using relativistic kinematics and a relativistic extension of the Schroedinger equation. A dispersive OMP with parameters that show a smooth energy dependence and energy independent geometry are determined from fits to the entire data set. A very good overall agreement between experimental data and predictions is achieved up to 150 MeV. Inclusion of nonlocality effects in the absorptive volume potential allows to achieve an excellent agreement up to 250 MeV.

  3. Optical constants and their dispersion of Ag-MgF2 nanoparticle composite films

    Institute of Scientific and Technical Information of China (English)

    Zhaoqi Sun(孙兆奇); Daming Sun(孙大明)

    2004-01-01

    Ag-MgF2 composite films with different Ag fractions were prepared through a co-evaporation method.Microstructure analysis shows that the films are composed of amorphous MgF2 matrix and embedded fcc-Ag nanoparticles. The optical constants and their dispersion of the films, within the wavelength range of 250 - 650 nm, were measured by reflecting spectroscopic ellipsometry. The maximum of the imaginary part ε" of the complex dielectric permittivity attributing to the surface plasmon resonance polarization of the Ag nanoparticles in an Ag-MgF2 film, and the tangent of the phase-shift angle δ resulting from the dielectric loss of the film, occur at λ = 435 nm and λ = 420 nm, respectively. Based on Maxwell-Garnett effective medium theory, the experimentally observed dispersion spectra were reasonably described.

  4. Graphene and silver-nanoprism dispersion for printing optically-transparent electrodes

    Science.gov (United States)

    Sinar, Dogan; Knopf, George K.; Nikumb, Suwas

    2017-02-01

    Optically transparent electrodes (OTEs) are used for bioelectronics, touch screens, visual displays, and photovoltaic cells. Although the conductive coating for these electrodes is often composed of indium tin oxide (ITO), indium is a very expensive material and thin ITO films are relatively brittle compared to conductive polymer or graphene thin films. An alternative highly conductive optically transparent thin film based on a graphene (G) and silver-nanoprism (AgNP) dispersion is introduced in this paper. The aqueous G ink is first synthesized using carboxymethyl cellulose (CMC) as a stabilizing agent. Silver (Ag) nanoprisms are then prepared separately by a simple thermal process which involves the reduction of silver nitrate by sodium borohydride. These Ag nanoprisms are only a few nanometers thick but have relatively large surface areas (>1000 nm2). As a consequence, the nanoprisms provide more efficient injection of free carriers to the G layer. The concentrated G-AgNP dispersions are then deposited on optically transparent glass and polyimide substrates using an inkjet printer with a HP6602A print head. After printing, these optically thin films can be thermally treated to further increase electrical conductivity. Thermal treatment decomposes CMC which frees elemental carbon from polymer chain and, simultaneously, causes the film to become hydrophobic. Preliminary experiments demonstrate that the G-AgNP films on glass substrates exhibit high conductivity at 70% transparency (550 nm). Additional tests on the Gr-AgNP thin films printed on polymide substrates show mechanical stability under bending with minimal reduction in electrical conductivity or optical transparency.

  5. Determination and analysis of dispersive optical constants of CuIn3S5 thin films

    Science.gov (United States)

    Khemiri, N.; Sinaoui, A.; Kanzari, M.

    2011-04-01

    CuIn3S5 thin films were prepared from powder by thermal evaporation under vacuum (10-6 mbar) onto glass substrates. The glass substrates were heated from 30 to 200 °C. The films were characterized for their optical properties using optical measurement techniques (transmittance and reflectance). We have determined the energy and nature of the optical transitions of films. The optical constants of the deposited films were determined in the spectral range 300-1800 nm from the analysis of transmission and reflection data. The Swanepoel envelope method was employed on the interference fringes of transmittance patterns for the determination of variation of refractive index with wavelength. Wemple-Di Domenico single oscillator model was applied to determine the optical constants such as oscillator energy E0 and dispersion energy Ed of the films deposited at different substrate temperatures. The electric free carrier susceptibility and the ratio of the carrier concentration to the effective mass were estimated according to the model of Spitzer and Fan.

  6. Refined Sellmeier and thermo-optic dispersion formulas for Li2B4O7

    Science.gov (United States)

    Umemura, Nobuhiro; Watanabe, Jun; Matsuda, Daisuke; Kamimura, Tomosumi

    2017-03-01

    We report the high-accuracy Sellmeier and thermo-optic dispersion formulas for Li2B4O7, which provide an excellent reproduction of the temperature-dependent phase-matching conditions for second-harmonic generation (SHG) and sum-frequency generation (SFG) in the 0.2093–1.5352 µm range. In addition, Li2B4O7 was found to be nearly 90° phase-matchable for fifth-harmonic generation (5HG) of an Yb-doped fiber laser at 1.031 µm.

  7. Frequency-Domain Chromatic Dispersion Equalization Using Overlap-Add Methods in Coherent Optical System

    CERN Document Server

    Xu, Tianhua; Popov, Sergei; Forzati, Marco; Martensson, Jonas; Mussolin, Marco; Li, Jie; Wang, Ke; Zhang, Yimo; Friberg, Ari T

    2016-01-01

    The frequency domain equalizers (FDEs) employing two types of overlap-add zero-padding (OLA-ZP) methods are applied to compensate the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent optical transmission system. Simulation results demonstrate that the OLA-ZP methods can achieve the same acceptable performance as the overlap-save method. The required minimum overlap (or zero-padding) in the FDE is derived, and the optimum fast Fourier transform length to minimize the computational complexity is also analyzed.

  8. A modified split—step fourier method for optical pulse propagation with polarization mode dispersion

    Institute of Scientific and Technical Information of China (English)

    RaoMin; SunXiao-Han; ZhangMing-De

    2003-01-01

    A modified split-step Fourier method (SSFM) is presented to solve the coupled nonlinear Schroedinger equation (CNLS) that can be used to model high-speed pulse propagation in optical fibres with polarization mode dispersion (PMD). We compare our approach with the SSFM and demonstrate that our approach is much faster with no loss of pre-chirped RZ(CRZ) formats in the presence of high PMD through this approach. The simulation results show that CRZ pulses are the most tolerant to high PMD values and the extinct ratio has a great impact on the transmission performance.

  9. Few-cycle pulse generation from noncollinear optical parametric amplifier with static dispersion compensation

    Science.gov (United States)

    Adachi, Shunsuke; Watanabe, Yuya; Sudo, Yuki; Suzuki, Toshinori

    2017-09-01

    We present a novel design of a few-cycle noncollinear optical parametric amplifier (NOPA) pumped by the second harmonic of a Ti:sapphire laser. A quasi-transform-limited sub-6 fs pulse width was realized by static dispersion compensation with commercially available chirped mirrors. The performance of the NOPA was tested by performing transient absorption spectroscopy on sensory rhodopsin II, and we observe short-lived oscillatory components that are associated with the vibrational coherence from the isomerizing molecule in the excited electronic state.

  10. Intrachannel cross-phase modulation-induced phase shift in high-speed dispersion-managed optical fiber transmission system

    Science.gov (United States)

    Syed, Nitu; Faisal, Mohammad

    2013-12-01

    We investigate the intrachannel cross-phase modulation (IXPM)-induced phase shift in optical return-to-zero pulse propagating in a periodically dispersion-managed long-haul optical fiber transmission line. Necessary dynamical equations for various pulse parameters have been derived using variational analysis to estimate the phase shift. These equations are solved by the Runge-Kutta method. The analytical result is verified by numerical simulation based on split-step Fourier method. We therefore explore the effects of various parameters, such as transmission distance, input power, duty cycle, dispersion map strength, and residual dispersion, on phase shift for a 40 Gb/s single-channel transmission system. We also check the impact of variation of bit rate on phase shift. We find that IXPM-induced phase shift can be mitigated by proper adjustment of dispersion management and different pulse parameters like duty cycle, dispersion map strength, and peak power.

  11. Dynamic Electronic Dispersion Equalization in Coherent Optical Networks Using Variable-Step-Size Least-Mean-Square Algorithm

    CERN Document Server

    Li, Liang

    2016-01-01

    In coherent detection employing digital signal processing, chromatic dispersion (CD) can be compensated effectively in the electrical domain. In practical optical transport networks, the signal lightpaths between two terminal nodes can be different due to current network conditions. Accordingly, the transmission distance and the accumulated dispersion in the lightpath cannot be predicted. Therefore, the adaptive compensation of dynamic dispersion such as the use of least-mean-square (LMS) algorithm is necessary in such optical fiber networks to enable a flexible routing and switching. In this paper, we present a detailed analysis on the adaptive dispersion compensation using the LMS algorithms in coherent optical transmission networks. Numerical simulations have been carried out accordingly. It can be found that the variable-step-size LMS equalizer can achieve the adaptive CD equalization with a lower complexity, compared to the traditional LMS algorithm.

  12. Novel technique for measuring intermodal dispersion in optical fibers using the spectral interference in the Michelson interferometer configuration

    Science.gov (United States)

    Hlubina, Petr

    1999-07-01

    The spectral interference between two modes of an optical fiber, which shows up as a periodic modulation of the source spectrum at its output, cannot be used to measure intermodal dispersion in the optical fiber when the period of modulation is too small to be resolved by a spectrometer. We proposed a novel measuring technique utilizing a tandem configuration of a dispersive Michelson interferometer and a two-mode optical fiber in which the intermodal interference can be restored, and consequently spectral interference fringes can be resolved, even if a low-resolution spectrometer is used. In the tandem configuration of the Michelson interferometer and the two-mode optical fiber, the optical path difference (OPD) in the Michelson interferometer is adjusted close to the group OPD between modes of the optical fiber so that the low-frequency spectral modulation that can be processed is produced. The feasibility of this technique has successfully been demonstrated in obtaining the wavelength dependence of the group OPD between two modes of the optical fiber. Using the Fourier transform method in processing the measured spectral modulations and subtracting the effect of the dispersive Michelson interferometer, the intermodal dispersion of the two-mode optical fiber has been obtained.

  13. Experimental Study on Time-Spread/Wavelength-Hop Optical Code Division Multiplexing with Dispersion-Compensating En/Decoder

    Institute of Scientific and Technical Information of China (English)

    Hideaki; Tamai; Hideyuki; Iwamura; Naoki; Minato; Saeko; Oshiba

    2003-01-01

    10Gbit/s time-spread/wavelength-hop optical code generation and decoding are performed by dispersion-compensating fiber Bragg grating (FBG) en/decoder pair. Error-free 10km single mode fiber (SMF) transmission of 10Gbit/s optical code division multiplexing (OCDM) has been experimentally demonstrated.

  14. Full distortion induced by dispersion evaluation and optical bandwidth constraining of fiber Bragg grating demultiplexers over analogue SCM systems.

    Science.gov (United States)

    Martinez, Alfonso; Pastor, Daniel; Capmany, Jose

    2002-12-30

    We provide a full analysis of the distortion effects produced by the first and second order in-band dispersion of fiber Bragg grating based optical demultiplexers over analogue SCM (Sub Carrier Multiplexed) signals. Optical bandwidth utilization ranges for Dense WDM network are calculated considering different SCM system cases of frequency extension and modulation conditions.

  15. The optical length effect, diffraction pattern and thermal lensing of Disperse Orange 25

    Science.gov (United States)

    Salmani, S.; Ara, M. H. Majles

    2016-08-01

    The nonlinear responses of an azo dye, Disperse Orange 25 (DO25), are investigated under two irradiation of continuous Lasers at 532 and 632 nm wavelengths and the third order refractive index is measured by use of Z-scan technique. At 632 nm wavelength (far from the absorption peak), the close z-scan plots show that this material has a very good nonlinear response with negative sign indicating self-defocusing. The effect of optical length and concentration of samples in nonlinear responses have been investigated experimentally. Also, the radius variation at far field observed due to thermal lens effect. Finally, at other wavelength, 532 nm (near from the absorption peak), the nonlinear optical responses increase sharply so the diffraction rings appear and the numbers of rings increase with the incident laser power.

  16. High-order optical nonlinearities in nanocomposite films dispersed with semiconductor quantum dots at high concentrations

    Science.gov (United States)

    Tomita, Yasuo; Matsushima, Shun-suke; Yamagami, Ryu-ichi; Jinzenji, Taka-aki; Sakuma, Shohei; Liu, Xiangming; Izuishi, Takuya; Shen, Qing

    2017-06-01

    We describe the nonlinear optical properties of inorganic-organic nanocomposite films in which semiconductor CdSe quantum dots as high as 6.8 vol.% are dispersed. Open/closed Z-scan measurements, degenerate multi-wave mixing and femtosecond pump-probe/transient grating measurements are conducted. It is shown that the observed fifth-order optical nonlinearity has the cascaded third-order contribution that becomes prominent at high concentrations of CdSe QDs. It is also shown that there are picosecond-scale intensity-dependent and nanosecond-scale intensity-independent decay components in absorptive and refractive nonlinearities. The former is caused by the Auger process, while the latter comes from the electron-hole recombination process.

  17. Optimised dispersion management and modulation formats for high speed optical communication systems

    DEFF Research Database (Denmark)

    Tokle, Torger

    2004-01-01

    This thesis studies dispersion management and modulation formats for optical communication systems using per channel bit rates at and above 10 Gbit/s. Novel modulation formats—including recently proposed multilevel phase modulation—are investigated and demonstrated at bit rates up to 80 Gbit/s. New...... system performance. Differential phase shift keying (DPSK) has recently been showed to be a promising modulation format for optical communication. We study DPSK with focus on differential quadrature phase shift keying (DQPSK). In a 12.5 Gbit/s WDM system, we demonstrate the suitability of DQPSK for ultra......-channel system, the optimum pulse width is very narrow. We find that a pulse width equal to 5% of the bit slot results in optimum performance for the system studied here. These narrow RZ pulses offer good receiver sensitivity and excellent tolerance to the nonlinear effect self phase modulation (SPM). However...

  18. Demonstration of a novel dispersive spectral splitting optical element for cost- effective photovoltaic conversion

    CERN Document Server

    Maragliano, Carlo; Bronzoni, Matteo; Rampino, Stefano; Fitzgerald, Eugene A; Chiesa, Matteo; Stefancich, Marco

    2015-01-01

    In this letter we report the preliminary validation of a low-cost paradigm for photovoltaic power generation that utilizes a prismatic Fresnel-like lens to simultaneously concentrate and separate sunlight into continuous laterally spaced spectral bands, which are then fed into spectrally matched single-junction photovoltaic cells. A prismatic lens was designed using geometric optics and the dispersive properties of the employed material, and its performance was simulated with a ray- tracing software. After device optimization, it was fabricated by injection molding, suitable for large-scale mass production. We report an average optical transmittance of ~ 90% over the VNIR range with spectral separation in excellent agreement with our simulations. Finally, two prototype systems were tested: one with GaAsP and c-Si photovoltaic devices and one with a pair of copper indium gallium selenide based solar cells. The systems demonstrated an increase in peak electrical power output of 51% and 64% respectively under wh...

  19. Porous silicon optical template for determination of chromatic dispersion of transparent liquid mixture

    Science.gov (United States)

    Cafe, Arven I.; Lopez, Joybelle; Lopez, Lorenzo; Faustino, Maria Angela; Mabilangan, Arvin; Salvador, Arnel; Somintac, Armando

    2017-03-01

    Porous silicon was fabricated through electrochemical etching and is used as an optical template for liquid sensing application. Using reflectance spectroscopy, change in optical properties such as refractive index and reflectivity upon liquid introduction were obtained. Chromatic dispersion of porous silicon upon detection of transparent liquids such as absolute ethanol, methanol, 2-propanol and distilled water were determined for spectral range 450nm to 1100nm. Mixture of the organic transparent liquid and water was also tested. In this study, porosity and liquid's concentration were varied to establish the sensitivity of detection. Expected ideal values were also simulated for comparison and correction factor computation. Results provide calibration basis for water quality assessment, environmental monitoring, and diagnostic application.

  20. Fiber optical parametric oscillator based on highly nonlinear dispersion-shifted fiber

    Institute of Scientific and Technical Information of China (English)

    Sigang YANG; Kenneth K. Y. WONG; Minghua CHEN; Shizhong XIE

    2013-01-01

    The development of fiber optical parametric oscillators (FOPO) based on highly nonlinear dispersion- shifted fiber is reviewed in this paper. Firstly, the background and motivation are introduced, and it is pointed out that the FOPO is promising to act as optical source in non-conventional wavelength bands. Subsequently, the context focuses principally on the problem of inherent multiple-longitudinal-mode characteristic of FOPO and the corresponding solutions to it. The primary technique is by locking the phase of multiple longitudinal modes. The first reported actively mode locked FOPO is also presented in this article. However, it is not probable to realize passively mode locked FOPO because of the random phase dithering of the pump required for suppressing stimulated Brillouin scattering. Furthermore, a regeneratively mode locked FOPO is demonstrated, which can generate wide band tunable radiation in non- conventional wavelengths. Besides mode locked FOPO, the single-longitudinal-mode FOPO is also introduced. Finally, potential future directions are discussed.

  1. Traumatic atlantoaxial rotatory fixation associated with C2 articular facet fracture in adult patient: Case report

    Directory of Open Access Journals (Sweden)

    Mehdi Bellil

    2014-01-01

    Full Text Available Traumatic atlantoaxial rotatory fixation is a very rare injury in adults which is often misdiagnosed initially. Its combination with C2 fractures is predominated by dens lesions. Therapeutic management is challenging because of the difficulty to achieve optimal reduction and permanent stability. We report a rare case of traumatic atlantoaxial rotatory fixation in a 56-year-old women associated with C2 articular facet fracture successfully treated by conservative means after patient-awake manual reduction with optimal functional and radiographic outcome.

  2. Observation and measurement of "giant" dispersive optical non-linearities in an ensemble of cold Rydberg atoms

    CERN Document Server

    Parigi, Valentina; Stanojevic, Jovica; Hilliard, Andrew J; Nogrette, Florence; Tualle-Brouri, Rosa; Ourjoumtsev, Alexei; Grangier, Philippe

    2012-01-01

    We observe and measure dispersive optical non-linearities in an ensemble of cold Rydberg atoms placed inside an optical cavity. The experimental results are in agreement with a simple model where the optical non-linearities are due to the progressive appearance of a Rydberg blockaded volume within the medium. The measurements allow a direct estimation of the "blockaded fraction" of atoms within the atomic ensemble.

  3. Dispersion compensation of fiber Bragg gratings in 3100 km high speed optical fiber transmission system

    Institute of Scientific and Technical Information of China (English)

    Li PEI; Tigang NING; Fengping YAN; Xiaowei DONG; Zhongwei TAN; Yan LIU; Shuisheng JIAN

    2009-01-01

    By optimizing the fabrication process of the chirped optical fiber Bragg grating (CFBG), some key problems of CFBG are solved, such as fabrication repetition, temperature stability, group delay ripple (GDR), fluctuation of the reflection spectrum, polarization mode dispersion (PMD), interaction of cascaded CFBG, and so on. The CFBG we fabricated can attain a temperature coefficient less than 0.0005 nm/℃, and the smoothed GDR and the fluctuation of the reflection spectrum are smaller than 10ps and 0.5dB, respec-tively. The PMD of each CFBG is less than 1 ps and the dispersion of each grating is larger than -2600 ps/(nm·km). With dispersion compensated by the CFBGs we fabricated, a 13×10 Gbit/s 3100 km ultra long G.652 fiber transmission system is successfully imple-mented without electric regenerator. The bit error rate (BER) of the system is below 10-4 without forward error correction (FEC); when FEC is added, the BER is below 10-12. The power penalty of the carrier-suppressed return-to-zero (CSRZ) code transmission system is only 2.5 dB.

  4. Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography

    Science.gov (United States)

    Schneider, Simon; Eppler, Florian; Weber, Marco; Olowojoba, Ganiu; Weiss, Patrick; Hübner, Christof; Mikonsaari, Irma; Freude, Wolfgang; Koos, Christian

    2016-08-01

    Nanocomposite materials represent a success story of nanotechnology. However, development of nanomaterial fabrication still suffers from the lack of adequate analysis tools. In particular, achieving and maintaining well-dispersed particle distributions is a key challenge, both in material development and industrial production. Conventional methods like optical or electron microscopy need laborious, costly sample preparation and do not permit fast extraction of nanoscale structural information from statistically relevant sample volumes. Here we show that optical coherence tomography (OCT) represents a versatile tool for nanomaterial characterization, both in a laboratory and in a production environment. The technique does not require sample preparation and is applicable to a wide range of solid and liquid material systems. Large particle agglomerates can be directly found by OCT imaging, whereas dispersed nanoparticles are detected by model-based analysis of depth-dependent backscattering. Using a model system of polystyrene nanoparticles, we demonstrate nanoparticle sizing with high accuracy. We further prove the viability of the approach by characterizing highly relevant material systems based on nanoclays or carbon nanotubes. The technique is perfectly suited for in-line metrology in a production environment, which is demonstrated using a state-of-the-art compounding extruder. These experiments represent the first demonstration of multiscale nanomaterial characterization using OCT.

  5. Hyperbranched-polymer dispersed nanocomposite volume gratings for holography and diffractive optics

    Science.gov (United States)

    Tomita, Yasuo; Takeuchi, Shinsuke; Oyaizu, Satoko; Urano, Hiroshi; Fukamizu, Taka-aki; Nishimura, Naoya; Odoi, Keisuke

    2016-10-01

    We review our experimental investigations of photopolymerizable nanoparticle-polymer composites (NPCs) for holography and diffractive optics. Various types of hyperbranched polymer (HBP) were systhesized and used as transporting organic nanoparticles. These HBPs include hyperbranched poly(ethyl methacrylate) (HPEMA), hyperbranched polystyrene (HPS) and hyperbranched triazine/aromatic polymer units (HTA) whose refractive indices are 1.51, 1.61 and 1.82, respectively. Each HBP was dispersed in (meth)acrylate monomer whose refractive index was so chosen that a refractive index difference between HBP and the formed polymer was large. Such monomer-HBP syrup was mixed with a titanocene photoinitiator for volume holographic recording in the green. We used a two-beam interference setup to write an unslanted transmission volume grating at grating spacing of 1 μm and at a wavelength of 532 nm. It is shown that NPC volume gratings with the saturated refractive index modulation amplitudes as large as 0.008, 0.004 and 0.02 can be recorded in NPCs incorporated with HPEMA, HPS and HTA at their optimum concentrations of 34, 34 and 25 vol.%, respectively. We show the usefulness of HBP-dispersed NPC volume gratings for holographic applications such as holographic data storage and diffractive optical devices.

  6. Attenuation of microwaves by poly-disperse small spheroid particles

    Science.gov (United States)

    Zhang, Peichang; Wang, Zhenhui

    1998-08-01

    Expressions for calculating the attenuation cross sections of poly-disperse, small spheroids, whose rotatory axes are in specific status, have been derived from a universal formula for calculating the attenuation cross section of a particle of arbitrary shape. Attenuation cross sections of liquid, ice, and spongy spheroidal droplets in different size and eccentricity at different wave lengths have been computed and analyzed.

  7. Master-Slave optical coherence tomography for parallel processing, calibration free and dispersion tolerance operation

    Science.gov (United States)

    Bradu, Adrian; Kapinchev, Konstantin; Barnes, Fred; Podoleanu, Adrian G.

    2015-03-01

    We present further improvements on the Master Slave (MS) interferometry method since our first communication [1]. In this paper, we present more data collection and additionally demonstrate an important feature of the MS method, that of tolerance to dispersion. MS interferometry produces the interference of a selected point in depth based on principles of spectral domain (SD) interferometry, but without the need of a Fast Fourier transformation (FFT). The method can be used to directly produce en-face optical coherence tomography (OCT) images but also as a tool to accurately measure distances in low coherence interferometry for sensing applications [1]. In the MS-OCT method, cross-correlation is applied to both methods of SD-OCT, spectrometer based (SP) or swept source (SS) OCT. The channelled spectrum provided by an OCT system is correlated with the signal produced by reading a stored mask. Several such masks can be used simultaneously. The masks operate as adaptive filters. Each mask (filter) determines recognition in the measured channelled spectrum delivered by the interferometer, of the pattern corresponding to each optical path difference to be recognized. The method presents net advantages in comparison with the classical method of producing axial reflectivity profiles by FFT: no need for resampling of data, possibility to tailor the trade-off between depth resolution and sensitivity. Here, using a swept source, the MS method is used to obtain axial reflectivity profiles, which are compared to the axial profiles obtained by calibration of data and FFT. The tolerance to dispersion of the MS method was assumed in [1] but not demonstrated. Here, measurements are performed to demonstrate its axial resolution independence on dispersion.

  8. Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Robles, Francisco E.; Fischer, Martin C.; Warren, Warren S.

    2016-03-01

    Stimulated Raman scattering (SRS) enables fast, high resolution imaging of chemical constituents important to biological structures and functional processes. While this technology has shown remarkable potential, it is currently limited to point scanning and can only probe a few Raman bands at a time. In this work we take a fundamentally different approach to detecting the small nonlinear signals based on dispersion effects that accompany the loss/gain processes in SRS. We use a modified pump-probe system (pulses with duration of ~0.5 ps and 75 fs, respectively) with interferometric detection in the Fourier-domain to demonstrate that the dispersive measurements are more robust to noise (e.g., laser noise) compared to conventional amplitude measurements, which in turn permits facile spectral and spatial multiplexing. Results show that it is possible to assess a broadband dispersion spectrum (currently limited to ~400 cm-1) with a single laser shot or spectrometer acquisition (20-50 µs). For molecular imaging with broadband spectral information, we achieve spatial pixel rates of 2.5 kHz, and will discuss how this can be further improved to 20-50 kHz. We also combine SRS with optical coherence tomography (OCT) (molecular and structural information are rendered from the same data), which enables axial multiplexing by coherence gating and paves the way for volumetric biochemical imaging. The approach is tested on a thin water-and-oil phantom, a thick scattering polystyrene bead phantom, and thick freshly excised human adipose tissue. Finally, we will outline other opportunities for spatial multiplexing using wide-field holography and spectroscopic-OCT, which would massively parallelize the spatial and spectral information. The combination of dispersion-based SRS and phase imaging has the potential to enable faster wide-area and volumetric molecular imaging. Such methods would be valuable in a clinical setting for many applications.

  9. Joint nonlinearity and chromatic dispersion pre-compensation for coherent optical orthogonal frequency-division multiplexing systems

    Institute of Scientific and Technical Information of China (English)

    Qiao Yao-Jun; Liu Xue-Jun; Ji Yue-Feng

    2011-01-01

    This paper introduces a joint nonlinearity and chromatic dispersion pre-compensation method for coherent optical orthogonal frequency-division multiplexing systems.The research results show that this method can reduce the walkoff effect and can therefore equalize the nonlinear impairments effectively. Compared with the only other existing nonlinearity pre-compensation method,the joint nonlinearity and chromatic dispersion pre-compensation method is not only suitable for low-dispersion optical orthogonal frequency-division multiplexing system,but also effective for highdispersion optical orthogonal frequency-division multiplexing transmission system with higher input power but without optical dispersion compensation.The suggested solution does not increase computation complexity compared with only nonlinearity pre-compensation method.For 40 Gbit/s coherent optical orthogonal frequency-division multiplexing 20 × 80 km standard single-mode fibre system,the suggested method can improve the nonlinear threshold (for Q > 10 dB) about 2.7,1.2 and 1.0 dB,and the maximum Q factor about 1.2,0.4 and 0.3 dB,for 2,8 and 16 ps/(nm·km) dispersion coefficients.

  10. Corrections for shear and rotatory inertia on flexural vibrations of beams

    NARCIS (Netherlands)

    Nederveen, C.J.; Schwarzl, F.R.

    1964-01-01

    Different correction formulae for the influence of shear and rotatory inertia on flexural vibrations of freely supported beams are compared with the exact solution. It appears that in most cases a simple formula is sufficient because of the appearance of a constant which is not accurately known, viz

  11. A C1-2 locked facet in a child with atlantoaxial rotatory fixation. Case report.

    Science.gov (United States)

    Missori, Paolo; Miscusi, Massimo; Paolini, Sergio; DiBiasi, Claudio; Finocchi, Vannina; Peschillo, Simone; Delfini, Roberto

    2005-12-01

    Conservative treatment is reported in a child with atlantoaxial rotatory fixation. Three-dimensional (3D) computerized tomography (CT) and magnetic resonance (MR) imaging demonstrated the degree of dislocation and alar ligament damage. A rigid cervical collar and muscle relaxant agents without any traction allowed full recovery. Control 3D CT scanning and MR imaging findings are reported.

  12. Propagation of bright femtosecond pulses in a nonlinear optical fibre with the third-and fourth-order dispersions

    Institute of Scientific and Technical Information of China (English)

    Ao Sheng-Mei; Yan Jia-Ren; Yu Hui-You

    2007-01-01

    We solve the generalized nonlinear Schrodinger equation describing the propagation of femtosecond pulses in a nonlinear optical fibre with higher-order dispersions by using the direct approach to perturbation for bright solitons, and discuss the combined effects of the third- and fourth-order dispersions on velocity, temporal intensity distribution and peak intensity of femtosecond pulses. It is noticeable that the combined effects of the third- and fourth-order dispersions on an initial propagated soliton can partially compensate each other, which seems to be significant for the stability controlling of soliton propagation features.

  13. Improvement of the chromatic dispersion tolerance in coherent optical OFDM systems using shifted DFT windows for ultra-long-haul optical transmission systems.

    Science.gov (United States)

    Sung, Minkyu; Kim, Hoon; Lee, Jaehoon; Jeong, Jichai

    2014-09-22

    In a high-capacity ultra-long-haul optical coherent orthogonal frequency-division multiplexing (CO-OFDM) system, the dispersion tolerance is determined by the length of cyclic extension (CE). In this paper, we propose a novel scheme to substantially improve the dispersion tolerance of CO-OFDM systems without increasing the CE length. Multiple time-shifted discrete Fourier transform (DFT) windows are exploited at the receiver, each demodulating only a part of the subcarriers. Effectively, the proposed scheme reduces the bandwidth of the OFDM signals under demodulation. Numerical simulations are performed to show the improved dispersion tolerance of the proposed scheme in comparison with the conventional CO-OFDM system. We show that the dispersion tolerance improves by a factor equal to the number of DFT windows. The tradeoff between the improved dispersion tolerance and increased receiver complexity is also presented.

  14. Multipath dispersion of pulse signals in a non-line-of-sight optical scattering channel

    Institute of Scientific and Technical Information of China (English)

    Tao Feng; Gang Chen; Zujie Fang

    2006-01-01

    Multipath-induced pulse broadening in a non-line-of-sight (NLOS) optical scattering channel is investigated. Expressions for impulse response and digital signal-to-noise ratio (DSNR) penalty induced by inter-symbol interference (ISI) of a NLOS ultraviolet (UV) scattering communication are introduced based ona single-scattering model, and simulated results for some typical atmospheric condition and configurationof geometry are given in the paper. It is shown that the multipath dispersion is one of the most importantfactors limiting the system performances, and return-to-zero (RZ) format is more suitable for the opticalscattering communications than non-return-to-zero (NRZ) format. The method proposed here can be usedto predict available bandwidth and data rate of the communication system operating in a NLOS opticalscattering channel.

  15. A modified split-step Fourier method for optical pulse propagation with polarization mode dispersion

    Institute of Scientific and Technical Information of China (English)

    饶敏; 孙小菡; 张明德

    2003-01-01

    A modified split-step Fourier method (SSFM) is presented to solve the coupled nonlinear Schrǒdinger equation (CNLS) that can be used to model high-speed pulse propagation in optical fibres with polarization mode dispersion (PMD). We compare our approach with the SSFM and démonstrate that our approach is much faster with no loss of accuracy. We discuss the pulse distortion and system Q-factor of non-return-to-zero (NRZ), return-to-zero (RZ) and pre-chirped RZ (CRZ) formats in the presence of high PMD through this approach. The simulation results show that CRZ pulses are the most tolerant to high PMD wlues and the extinct ratio has a great impact on the transmission performance.

  16. Squeezing spectra from s-ordered quasiprobability distributions. Application to dispersive optical bistability

    CERN Document Server

    Garcia-Ferrer, F V; De Valcarcel, G J; Roldan, E; Garcia-Ferrer, Ferran V.; Perez-Arjona, Isabel; Valcarcel, German J. de; Roldan, Eugenio

    2005-01-01

    It is well known that the squeezing spectrum of the field exiting a nonlinear cavity can be directly obtained from the fluctuation spectrum of normally ordered products of creation and annihilation operators of the cavity mode. In this article we show that the output field squeezing spectrum can be derived also by combining the fluctuation spectra of any pair of s-ordered products of creation and annihilation operators. The interesting result is that the spectrum obtained in this way from the linearized Langevin equations is exact, and this occurs in spite of the fact that no s-ordered quasiprobability distribution verifies a true Fokker-Planck equation, i.e., the Langevin equations used for deriving the squeezing spectrum are not exact. The (linearized) intracavity squeezing obtained from any s-ordered distribution is also exact. These results are exemplified in the problem of dispersive optical bistability.

  17. Analysis of excited-state Faraday anomalous dispersion optical filter at 1529 nm.

    Science.gov (United States)

    Xiong, Junyu; Yin, Longfei; Luo, Bin; Guo, Hong

    2016-06-27

    In this work, a detailed theoretical analysis of 1529 nm ES-FADOF (excited state Faraday anomalous dispersion optical filter) based on rubidium atoms pumped by 780 nm laser is introduced, where Zeeman splitting, Doppler broadening, and relaxation processes are considered. Experimental results are carefully compared with the derivation. The results prove that the optimal pumping frequency is affected by the working magnetic field. The population distribution among all hyperfine Zeeman sublevels under the optimal pumping frequency has also been obtained, which shows that 85Rb atoms are the main contribution to the population. The peak transmittance above 90% is obtained, which is in accordance with the experiment. The calculation also shows that the asymmetric spectra observed in the experiment are caused by the unbalanced population distribution among Zeeman sublevels. This theoretical model can be used for all kinds of calculations for FADOF.

  18. Wavelength dependent measurements of optical fiber transit time, material dispersion, and attenuation

    Energy Technology Data Exchange (ETDEWEB)

    COCHRANE,KYLE ROBERT; BAILEY,JAMES E.; LAKE,PATRICK WAYNE; CARLSON,ALAN L.

    2000-04-18

    A new method for measuring the wavelength dependence of the transit time, material dispersion, and attenuation of an optical fiber is described. The authors inject light from a 4-ns risetime pulsed broad-band flashlamp into various length fibers and record the transmitted signals with a time-resolved spectrograph. Segments of data spanning an approximately 3,000 {angstrom} range are recorded from a single flashlamp pulse. Comparison of data acquired with short and long fibers enables the determination of the transit time and the material dispersion as functions of wavelength dependence for the entire recorded spectrum simultaneously. The wavelength dependent attenuation is also determined from the signal intensities. The method is demonstrated with experiments using a step index 200-{micro}m-diameter SiO{sub 2} fiber. The results agree with the transit time determined from the bulk glass refractive index to within {+-} 0.035% for the visible (4,000--7,200 {angstrom}) spectrum and 0.12% for the ultraviolet (2,650--4,000 {angstrom}) spectrum, and with the attenuation specified by the fiber manufacturer to within {+-} 10%.

  19. Concept and optical design of the cross-disperser module for CRIRES+

    CERN Document Server

    Oliva, E; Ferruzzi, D; Origlia, L; Hatzes, A; Follert, R; Loewinger, T; Piskunov, N; Heiter, U; Lockhart, M; Marquart, T; Stempels, E; Reiners, A; Anglada-Escude, G; Seemann, U; Dorn, R J; Bristow, P; Baade, D; Delabre, B; Gojak, D; Grunhut, J; Klein, B; Hilker, M; Ives, D J; Jung, Y; Kaeufl, H U; Kerber, F; Lizon, J L; Pasquini, L; Paufique, J; Pozna, E; Smette, A; Smoker, J; Valenti, E

    2014-01-01

    CRIRES, the ESO high resolution infrared spectrometer, is a unique instrument which allows astronomers to access a parameter space which up to now was largely uncharted. In its current setup, it consists of a single-order spectrograph providing long-slit, single-order spectroscopy with resolving power up to R=100,000 over a quite narrow spectral range. This has resulted in sub-optimal efficiency and use of telescope time for all the scientific programs requiring broad spectral coverage of compact objects (e.g. chemical abundances of stars and intergalactic medium, search and characterization of extra-solar planets). To overcome these limitations, a consortium was set-up for upgrading CRIRES to a cross-dispersed spectrometer, called CRIRES+. This paper presents the updated optical design of the crossdispersion module for CRIRES+. This new module can be mounted in place of the current pre-disperser unit. The new system yields a factor of >10 increase in simultaneous spectral coverage and maintains a quite long ...

  20. Ultra-narrow bandwidth optical filters consisting of one-dimensional photonic crystals with anomalous dispersion materials

    Institute of Scientific and Technical Information of China (English)

    Liu Jiang-Tao; Zhou Yun-Song; Wang Fu-He; Gu Ben-Yuan

    2005-01-01

    We present a new type of optical filter with an ultra-narrow bandwidth and a wide field-of-view (FOV). This kind of optical filter consists of one-dimensional photonic crystal (PC) incorporating an anomalous-dispersion-material (ADM) with, for instance, an anomalous dispersion of 6P3/2 ← 6S1/2 hyperfine structure transition of a caesium atom.The transmission spectra of optical filters are calculated by using the transfer-matrix method. The simulation results show that the designed optical filter has a bandwidth narrower than 0.33GHz and a wide FOV of ±30° as well. The response of transmission spectrum to an external magnetic field is also investigated.

  1. Determination of refractive index dispersion using fiber-optic low-coherence Fabry-Perot interferometer: implementation and validation

    Science.gov (United States)

    Karpienko, Katarzyna; Wróbel, Maciej S.; Jędrzejewska-Szczerska, Małgorzata

    2014-07-01

    We present the implementation and validation of low-coherence Fabry-Perot interferometer for refractive index dispersion measurements of liquids. A measurement system has been created with the use of four superluminescent diodes with different optical parameters, a fiber-optic coupler and an optical spectrum analyzer. The Fabry-Perot interferometer cavity has been formed by the fiber-optic end and mirror surfaces mounted on a micromechanical stage. The positive result of the validation procedure has been determined through statistical analysis. All obtained results were 99.999% statistically significant and were characterized by a strong positive correlation (r>0.98). The accuracy of the measured result of implemented low-coherence Fabry-Perot interferometer sensor is from 83% to 94%, which proves that the sensor can be used in the measurement of refractive index dispersion of liquids.

  2. Nucleon scattering on actinides using a dispersive optical model with extended couplings

    Science.gov (United States)

    Soukhovitskiĩ, E. Sh.; Capote, R.; Quesada, J. M.; Chiba, S.; Martyanov, D. S.

    2016-12-01

    The Tamura coupling model [Rev. Mod. Phys. 37, 679 (1965), 10.1103/RevModPhys.37.679] has been extended to consider the coupling of additional low-lying rotational bands to the ground-state band. Rotational bands are built on vibrational bandheads (even-even targets) or single-particle bandheads (odd-A targets) including both axial and nonaxial deformations. These additional excitations are introduced as a perturbation to the underlying axially symmetric rigid-rotor structure of the ground-state rotational band. Coupling matrix elements of the generalized optical model are derived for extended multiband transitions in even-even and odd-A nuclei. Isospin symmetric formulation of the optical model is employed. A coupled-channels optical-model potential (OMP) containing a dispersive contribution is used to fit simultaneously all available optical experimental databases including neutron strength functions for nucleon scattering on 232Th,233,235,238U, and 239Pu nuclei. Quasielastic (p ,n ) scattering data on 232Th and 238U to the isobaric analog states of the target nucleus are also used to constrain the isovector part of the optical potential. Lane consistent OMP is derived for all actinides if corresponding multiband coupling schemes are defined. For even-even (odd-A ) actinides almost all low-lying collective levels below 1 MeV (0.5 MeV) of excitation energy are coupled. OMP parameters show a smooth energy dependence and energy-independent geometry. A phenomenological optical-model potential that couples multiple bands in odd-A actinides is published for a first time. Calculations using the derived OMP potential reproduce measured total cross-section differences between several actinide pairs within experimental uncertainty for incident neutron energies from 50 keV up to 150 MeV. The importance of extended coupling is studied. Multiband coupling is stronger in even-even targets owing to the collective nature of the coupling; the impact of extended coupling on

  3. Dispersion-model-free determination of optical constants: application to materials for organic thin film devices.

    Science.gov (United States)

    Flämmich, Michael; Danz, Norbert; Michaelis, Dirk; Bräuer, Andreas; Gather, Malte C; Kremer, Jonas H-W M; Meerholz, Klaus

    2009-03-10

    We describe a method to determine the refractive index and extinction coefficient of thin film materials without prior knowledge of the film thickness and without the assumption of a dispersion model. A straightforward back calculation to the optical parameters can be performed starting from simple measurements of reflection and transmission spectra of a 100-250 nm thick supported film. The exact film thickness is found simultaneously by fulfilling the intrinsic demand of continuity of the refractive index as a function of wavelength. If both the layer and the substrate are homogeneous and isotropic media with plane and parallel interfaces, effects like surface roughness, scattering, or thickness inhomogeneities can be neglected. Then, the accuracy of the measurement is approximately 10(-2) and 10(-3) for the refractive index and the extinction coefficient, respectively. The error of the thin film thickness determination is well below 1 nm. Thus this technique is well suited to determine the input parameters for optical simulations of organic thin film devices, such as organic light-emitting diodes (OLEDs) or organic photovoltaic (OPV) cells. We apply the method to the electroluminescent polymer poly(2,5-dioctyl-p-phenylene vinylene) (PDO-PPV) and show its applicability by comparing the measured and calculated reflection and transmission spectra of OLED stacks with up to five layers.

  4. Optical properties of Au-dispersed ZrO2 thin films

    Science.gov (United States)

    Huang, Weimin; Arizpe-Chávez, Humberto; Ramírez-Bon, Rafael; Espinoza-Beltrán, Francisco

    2002-03-01

    The optical absorption of gold nanoparticles dispersed within mesoporous zirconia thin films has been investigated. The samples of this material were prepared by the sol-gel technique. TEM studies showed Au nanoparticles with sizes in the range from 5 to 20 nm, embedded into the zirconia matrix. Also, XR diffraction spectra showed Au diffraction peaks corresponding to metallic nanoparticles with sizes in the range 7-9 nm. The accepted surface plasma resonance value for gold is 556 nm. The absorption spectra showed a red shift on the SPR position for samples thermally annealed. Also, a red shift is observed for samples treated with monoethanolamine (MEA) vapor. A lowering in the intensities of the absorption peaks for the treated samples is observed. On the other hand, larger gold dopping produces a blue shift in the absorption spectra, with an increment in the intensity of the absorption peaks. The Tauc-Lorentz fitting model allowed us to measure changes in the dielectric function of the material. Therefore, we conclude that not only the particle size drives the optical absorption spectra in gold-doped films. The observed opposite results can be explained if we introduce changes in the dielectric constant of the films.

  5. An Optically Pumped Magnetometer Working in the Light-Shift Dispersed Mz Mode.

    Science.gov (United States)

    Schultze, Volkmar; Schillig, Bastian; IJsselsteijn, Rob; Scholtes, Theo; Woetzel, Stefan; Stolz, Ronny

    2017-03-10

    We present an optically pumped magnetometer working in a new operational mode-the light-shift dispersed Mz (LSD-Mz) mode. It is realized combining various features; (1) high power off-resonant optical pumping; (2) Mz configuration, where pumping light and magnetic field of interest are oriented parallel to each other; (3) use of small alkali metal vapor cells of identical properties in integrated array structures, where two such cells are pumped by circularly polarized light of opposite helicity; and (4) subtraction of the Mz signals of these two cells. The LSD-Mz magnetometer's performance depends on the inherent and very complex interplay of input parameters. In order to find the configuration of optimal magnetometer resolution, a sensitivity analysis of the input parameters by means of Latin Hypercube Sampling was carried out. The resulting datasets of the multi-dimensional parameter space exploration were assessed by a subsequent physically reasonable interpretation. Finally, the best shot-noise limited magnetic field resolution was determined within that parameter space. As the result, using two 50 mm3 integrated vapor cells a magnetic field resolution below 10 fT/√Hz at Earth's magnetic field strength is possible.

  6. Third-Order Nonlinear Optical Behavior of Novel Polythiophene Derivatives Functionalized with Disperse Red 19 Chromophore

    Directory of Open Access Journals (Sweden)

    Marilú Chávez-Castillo

    2015-01-01

    Full Text Available Two copolymers of 3-alkylthiophene (alkyl = hexyl, octyl and a thiophene functionalized with disperse red 19 (TDR19 as chromophore side chain were synthesized by oxidative polymerization. The synthetic procedure was easy to perform, cost-effective, and highly versatile. The molecular structure, molecular weight distribution, film morphology, and optical and thermal properties of these polythiophene derivatives were determined by NMR, FT-IR, UV-Vis GPC, DSC-TGA, and AFM. The third-order nonlinear optical response of these materials was performed with nanosecond and femtosecond laser pulses by using the third-harmonic generation (THG and Z-scan techniques at infrared wavelengths of 1300 and 800 nm, respectively. From these experiments it was observed that although the TRD19 incorporation into the side chain of the copolymers was lower than 5%, it was sufficient to increase their nonlinear response in solid state. For instance, the third-order nonlinear electric susceptibility (χ3 of solid thin films made of these copolymers exhibited an increment of nearly 60% when TDR19 incorporation increased from 3% to 5%. In solution, the copolymers exhibited similar two-photon absorption cross sections σ2PA with a maximum value of 8545 GM and 233 GM (1 GM = 10−50 cm4 s per repeated monomeric unit.

  7. Optical pH measurements with water dispersion of polyaniline nanoparticles and their redox sensitivity.

    Science.gov (United States)

    Lindfors, Tom; Harju, Leo; Ivaska, Ari

    2006-05-01

    A new method for optical pH and redox measurements with a commercially available water dispersion of polyaniline (PANI) nanoparticles (mean particle size, 46 nm) is presented. The pH measurements are based on the acid-base equilibrium of PANI and were carried out either by combining both the automated sequential injection analysis (SIA) and UV-visible spectrophotometric techniques or with a fiber-optic light guide. In the former case, the detection was done in continuous mode at lambda = 800 nm by using the SIA technique for transporting the sample to a flow-through cell, which was placed in the light path of the photometer. With the fiber-optic light guide, the detection was done in batch mode at lambda = 400 and 580 nm. In both methods, fresh pH reagent (PANI) solution was used in each measurement, thus overcoming the problem with hysteresis (memory effect), which is usually observed with PANI films. The PANI nanoparticles were characterized with UV-visible spectroscopy in pH buffer solutions between pH 2-12 and a protonation constant of logK(0.5H,L)(H(0.5)L) = 4.4 was calculated from these data. Fast pH measurements can be done between pH 6 and 10.5 depending on the measuring technique. It is possible to determine pH with an accuracy of 0.1 pH unit between pH 8 and 10.5 (RSD, 0.5-2%). Redox transitions typical for PANI films were also observed for water solutions of PANI nanoparticles in the presence of the hexacyanoferrate(II/III) and the iron(II/III) oxalate redox couples. The absorbance at lambda = 875 nm is linearly dependent on the logarithm of the concentration ratio (0.1-10) of the iron oxalate redox couple.

  8. Limitations in distance and frequency due to chromatic dispersion in fibre-optic microwave and millimeter-wave links

    DEFF Research Database (Denmark)

    Gliese, Ulrik Bo; Nielsen, Søren Nørskov

    1996-01-01

    Chromatic dispersion significantly limits the distance and/or frequency in fibre-optic microwave and millimeter-wave links based on direct detection due to a decrease of the carrier to noise ratio. The limitations in links based on coherent remote heterodyne detection, however, are far less...

  9. Dispersions of Semiconductor Nanoparticles in Thermotropic Liquid Crystal: From Optical Modification to Assisted Self-Assembly

    Science.gov (United States)

    Rodarte, Andrea L.

    The interaction of semiconducting quantum dot nanoparticles (QDs) within thermotropic liquid crystalline (LC) materials are studied in this thesis. LC materials are ideal for bottom-up organization of nanoparticles as an active matrix that can be externally manipulated via electric or magnetic fields. In addition, the optical properties of QDs can be modified by the surrounding LC resulting in novel devices such as a quantum dot/liquid crystal laser. The first system studies the dispersion of spherical nanoparticles in the phase. The dispersion is investigated with the use of polarized optical microscopy, fluorescence microscopy and confocal scanning microscopy. Quantum dots well dispersed in the isotropic phase are expelled from ordered domains of LC at the phase transition. Under controlled conditions, the majority of QDs in the system can form ordered three dimensional assemblies that are situated at defect points in the liquid crystal. The internal order of the assemblies is probed utilizing Forster resonance energy transfer (FRET), combined with small angle X-ray scattering (SAXS). Furthermore, the location of these assemblies can be predetermined with the use of beads as defect nucleation points in the cell. The interaction of QDs in a cholesteric liquid crystal (CLC) is also investigated. The reflection band created by the periodic change of index of refraction in a planar aligned CLC acts as a 1-D photonic cavity when the CLC is doped with a low concentration of QDs. A Cano-wedge cell varies the pitch of the CLC leading to the formation of Grandjean steps. This spatially tunes the photonic stop band, changing the resonance condition and continuously altering both the emission wavelength and polarization state of the QD ensemble. Using high resolution spatially and spectrally resolved photoluminescence measurements, the emission is shown to be elliptically polarized and that the tilt of the ellipse, while dependent on the emission wavelength, additionally

  10. Dispersion-Induced Waveform Distortion Detection in 42.7 Gbps CS-RZ Signals by Optical Time Domain Level Monitoring

    Institute of Scientific and Technical Information of China (English)

    Yoshitaka; Yokoyama; Kiyoshi; Fukuchi

    2003-01-01

    We propose a technique for chromatic dispersion monitoring based on optical time domain level monitoring. Experimental and simulation results show that the technique is effective for the monitoring of dispersion in 42.7-Gbps CS-RZ signals for dynamic dispersion compensation.

  11. Ultra-flat and broad optical frequency combs generation based on novel dispersion-flattened double-slot microring resonator

    Science.gov (United States)

    Wang, Yuanwu; Zhang, Minming; Lu, Luluzi; Li, Meifeng; Wang, Jinghao; Zhou, Feiya; Dai, Jing; Deng, Lei; Liu, Deming

    2016-01-01

    In this paper, a novel double-slot microring resonator is proposed to produce flat dispersion of 0-3.8 ps/(nm km) over 1150 nm wavelength range. Moreover, the dispersion tailoring with different structural parameters of the proposed microring resonator is analyzed and simulated. The simulation results show that the dispersion fluctuation can be tailored by the height of the central and bottom As2S3 layer, and the slope can be adjusted by the waveguide width and lower SiO2 slot thickness. Furthermore, by means of the Lugiato-Lefever equation, an ultra-flat and broad optical frequency comb with 7-dB bandwidth of 1155 nm (1855-3010 nm) is obtained based on such dispersion-optimized resonator. The proposed double-slot microring resonator shows potential application in both telecommunication and mid-infrared research domain.

  12. Optical mode confinement in three-dimensional Al/SiO2 nano-cavities with hyperbolic dispersion

    Science.gov (United States)

    Bacco, Carla; Kelly, Priscilla; Kuznetsova, Lyuba

    2015-09-01

    Today's technological needs are demanding for faster and smaller optical components. Optical microcavities offer a high confinement of electromagnetic field in a small volume, with dimensions comparable to the wavelength of light, which provides a unique system for the enhancement of light-matter interactions on the nanoscale. However, further reducing the size of the optical cavity (from microcavity to nanocavity) is limited to the fundamental diffraction limit. In hyperbolic metamaterials, large wave vectors can be achieved. Therefore, optical cavities, created from hyperbolic metamaterials, allow the confinement of the electromagnetic field to an extremely small volume with dimensions significantly smaller than the wavelength of light. This paper presents the results of numerical study of the optical mode confinement in nanocavities with hyperbolic dispersion using nanolayered Al/SiO2 hyperbolic metamaterial with different Al fill fractions. The fundamental properties of the optical modes and resonance frequencies for the nanocavities are studied using the finite-elementmethod numerical technique. Numerical simulations show that the light can be well confined in a disk with radius up to λ/65. This paper will also focus on other variables such as Q-factor and Al fill fraction. Potential future applications for three-dimensional nanocavities with hyperbolic dispersion include: silicon photonics optical communications networks, ultrafast LEDs and biological nanoparticles sensing.

  13. General demonstration of principal states of polarization and real-time monitoring of polarization mode dispersion in optical fibres

    Institute of Scientific and Technical Information of China (English)

    Dong Hui; Wu Chong-Qing; Fu Song-Nian

    2004-01-01

    We investigated the general properties of polarization effects in optical fibres and demonstrated the existence of socalled principal states of polarization (PSP), which mean the fixed points in mathematics, in different polarization effects,such as birefringence and polarization mode dispersion, by using fixed point theory. Furthermore, a time evolution vector is defined to describe the time evolution of polarization state in optical fibres, which is used to investigate the time evolution of polarization mode dispersion vector (PDV), including differential group delay and PSP. The experimentalresults of real-time monitoring of PDV by using this method are reported. To our knowledge, this is the first report on monitoring PSP evolution in optical fibres.

  14. Characterization of optical constants and dispersion parameters of highly transparent Ge20Se76Sn4 amorphous thin film

    Science.gov (United States)

    Abd-Elrahman, M. I.; Hafiz, M. M.; Abdelraheem, A. M.; Abu-Sehly, A. A.

    2015-12-01

    Amorphous chalcogenide Ge20Se76Sn4 thin films of six different thicknesses (50-350 nm) are prepared by the thermal evaporation technique. Optical transmission and reflection spectra, in the wavelength range of the incident photons from 250 to 2500 nm, are used to study the effect of the film thickness on some optical properties. It is found that the effect of film thickness leads to increase in the absorption coefficient, refractive index, extinction coefficient and the width of the tails of localized states in the gap region. The decrease in optical band gap energy with increasing the film thickness is attributed to the formation of a band tail which narrows down the band gap. Dispersion analyses of refractive index reveal a decrease in the single-oscillator energy and an increase in the dispersion energy with increase in film thickness.

  15. Optical mode confinement in the Al/SiO2 disk nanocavities with hyperbolic dispersion in the infrared spectral region

    Science.gov (United States)

    Bacco, Carla; Kelly, Priscilla; Kuznetsova, Lyuba

    2016-10-01

    This paper presents the results of a numerical study of the optical mode confinement in whispering gallery mode disk nanocavities with hyperbolic dispersion using nanolayered Al/SiO2 hyperbolic metamaterial with different Al fill fractions. The fundamental properties of the optical modes and resonance frequencies for the disk nanocavities are studied using the numerical finite-element method. Numerical simulations show that light can be well confined in a disk nanocavity with a radius of up to an order of magnitude smaller than free-space resonant wavelength. This paper will also focus on how Purcell factor and quality factor of the disk nanocavities are affected by the fill fraction of the aluminum in the nanolayered metamaterial. Potential future applications for disk nanocavities with hyperbolic dispersion include silicon photonics optical communications networks, ultrafast LEDs, and biological nanoparticles sensing.

  16. 0.54 {\\mu}m resolution two-photon interference with dispersion cancellation for quantum optical coherence tomography

    CERN Document Server

    Okano, Masayuki; Okamoto, Ryo; Nishizawa, Norihiko; Kurimura, Sunao; Takeuchi, Shigeki

    2016-01-01

    Quantum information technologies harness the intrinsic nature of quantum theory to beat the limitations of the classical methods for information processing and communication. Recently, the application of quantum features to metrology has attracted much attention. Quantum optical coherence tomography (QOCT), which utilizes two-photon interference between entangled photon pairs, is a promising approach to overcome the problem with optical coherence tomography (OCT): As the resolution of OCT becomes higher, degradation of the resolution due to dispersion within the medium becomes more critical. Here we report on the realization of 0.54 $\\mu$m resolution two-photon interference, which surpasses the current record resolution 0.75 $\\mu$m of low-coherence interference for OCT. In addition, the resolution for QOCT showed almost no change against the dispersion of a 1 mm thickness of water inserted in the optical path, whereas the resolution for OCT dramatically degrades. For this experiment, a highly-efficient chirpe...

  17. KINEMATIC ANALYSIS OF THE POSTERIOR ELEMENT OF LUMBAR SPINE IN ROTATORY CHIROPRACTIC

    Institute of Scientific and Technical Information of China (English)

    侯筱魁; 董凡; 戴克戎; 汤荣光; 魏晋兵

    1993-01-01

    Rotatory chiropractic is one of the key manipulations in the treatment of low-er backache. The present paper reports the kinematic changes in the posterior element oflumbar spine during rotatory manipulation, using motion segments of lumbar spine fromfresh cadavers as specimens and an electromechanical system for the measurements. Theanalysis of the angle-displacement curve and the load-angle curve reveals that rotatorychiropractic is a kind of complicated 3-D. 6-degree-of-freedom motion. Correctmanipulation may adjust the volume of the nerve root canal and relax the articulation be-tween the upper and lower joint processes so as to relieve the adhesion of the enclosuresin the nerve root canal and relieve the adhesion of the facet joints, and bring aboutimprovement of local circulation and amelioration of symptoms.

  18. Atlantoaxial Rotatory Subluxation after Removal of a Ventriculoperitoneal Shunt in the Supine-Lateral Position.

    Science.gov (United States)

    Hashide, Shusei; Aihara, Yasuo; Nagahara, Ayumi; Mitsuyama, Tetsuryu; Okada, Yoshikazu

    2015-01-01

    Atlantoaxial rotatory subluxation (AARS) is an uncommon disease with a greater prevalence in children than adults. So far there has only been one report of AARS after surgery related to ventriculoperitoneal (VP) shunting. We present a new case of AARS closed reduction treatment after VP shunt removal in an 8-year-old girl with wound pain on the back of her head and torticollis after surgery. Her head was rotated in the spine-lateral position during surgery. The diagnosis of AARS was established by 3D-computed tomography. The rotatory subluxation was cured after cervical traction therapy. The successful closed reduction was the consequence of early detection and conservative treatment, which are important constituents in the management of AARS. © 2015 S. Karger AG, Basel.

  19. Atlanto axial rotatory dislocation in adults: a rare complication of an epileptic seizure--case report.

    Science.gov (United States)

    Tarantino, Roberto; Donnarumma, Pasquale; Marotta, Nicola; Missori, Paolo; Viozzi, Ilaria; Landi, Alessandro; Delfini, Roberto

    2014-01-01

    Atlanto Axial Rotatory Dislocations (AARDs) are a heterogeneous group of post-traumatic pathologies typical of the pediatric age, and rare in adults. We describe the case of a 34-year-old woman, developing Atlanto Axial Rotatory Fixation (AARF) after a generalized tonic-clonic epileptic seizure, an extremely rare traumatic cause never described in literature. AARF was detected only 1 month after the accident and nonsurgical treatment was attempted at the beginning. The patient underwent surgery only 2 months after the accident. The best treatment should be conservative reduction within 1 month; when it is not possible, it is advisable to perform surgery as soon as possible. C1-C2 fixation with Harm's technique is the gold standard for fixed luxations. Delay of treatment makes intraoperative reduction more difficult and increase the establishment of the chronic permanent change of neck muscles and ligaments.

  20. Atlanto Axial Rotatory Dislocation in Adults: A Rare Complication of an Epileptic Seizure—Case Report

    Science.gov (United States)

    TARANTINO, Roberto; DONNARUMMA, Pasquale; MAROTTA, Nicola; MISSORI, Paolo; VIOZZI, Ilaria; LANDI, Alessandro; DELFINI, Roberto

    2014-01-01

    Atlanto Axial Rotatory Dislocations (AARDs) are a heterogeneous group of post-traumatic pathologies typical of the pediatric age, and rare in adults. We describe the case of a 34-year-old woman, developing Atlanto Axial Rotatory Fixation (AARF) after a generalized tonic-clonic epileptic seizure, an extremely rare traumatic cause never described in literature. AARF was detected only 1 month after the accident and nonsurgical treatment was attempted at the beginning. The patient underwent surgery only 2 months after the accident. The best treatment should be conservative reduction within 1 month; when it is not possible, it is advisable to perform surgery as soon as possible. C1–C2 fixation with Harm's technique is the gold standard for fixed luxations. Delay of treatment makes intraoperative reduction more difficult and increase the establishment of the chronic permanent change of neck muscles and ligaments. PMID:24201098

  1. Posterolateral rotatory instability of the elbow: a case report and literature review.

    Science.gov (United States)

    Yang, Chen; Li, Wei; Gong, Yu-bao; Li, Shu-qiang; Qi, Xin

    2010-12-01

    Posterolateral rotatory instability of the elbow describes a condition that radial head subluxation or dislocation occurs when forearm rotates externally in relation to humerus. It is difficult to diagnose and treat. We reported a typical case which was confirmed by physical examination and MR images. Ligamentous insufficiency was confirmed under direct vision, and was reconstructed with triceps fascia as described by Gong et al with slight modification. Regain of full function was achieved one year after surgery.

  2. Posterolateral rotatory instability of the elbow: a case report and literature review

    Institute of Scientific and Technical Information of China (English)

    YANG Chen; LI Wei; GONG Yu-bao; LI Shu-qiang; QI Xin

    2010-01-01

    Posterolateral rotatory instability of the elbow describes a condition that radial head subluxation or dislocation occurs when forearm rotates externally in relation to humerus. It is difficult to diagnose and treat. We reported a typical case which was confirmed by physical examination and MR images. Ligamentous insufficiency was confirmed under direct vision, and was reconstructed with triceps fascia as described by Gong et al with slight modification. Regain of full function was achieved one year after surgery.

  3. An experimental indoor phasing system based on active optics using dispersed Hartmann sensing technology in the visible waveband

    Institute of Scientific and Technical Information of China (English)

    Yong Zhang; Gen-Rong Liu; Yue-Fei Wang; Ye-Ping Li; Ya-Jun Zhang; Liang Zhang; Yi-Zhong Zeng; Jie Zhang

    2011-01-01

    A telescope with a larger primary mirror can collect much more light and resolve objects much better than one with a smaller mirror,and so the larger version is always pursued by astronomers and astronomical technicians.Instead of using a monolithic primary mirror,more and more large telescopes,which are currently being planned or in construction,have adopted a segmented primary mirror design.Therefore,how to sense and phase such a primary mirror is a key issue for the future of extremely large optical/infrared telescopes.The Dispersed Fringe Sensor (DFS),or Dispersed Hartmann Sensor (DHS),is a non-contact method using broadband point light sources and it can estimate the piston by the two-directional spectrum formed by the transmissive grating's dispersion and lenslet array.Thus it can implement the combination of co-focusing by Shack-Hartmann technology and phasing by dispersed fringe sensing technologies such as the template-mapping method and the Hartmann method.We introduce the successful design,construction and alignment of our dispersed Hartmann sensor together with its design principles and simulations.We also conduct many successful real phasing tests and phasing corrections in the visible waveband using our existing indoor segmented mirror optics platform.Finally,some conclusions are reached based on the test and correction of experimental results.

  4. The effect of betahistine on vestibular habituation: comparison of rotatory and sway habituation training.

    Science.gov (United States)

    Mierzwinski, J; Kazmierczak, H; Pawlak-Osinska, K; Piziewicz, A

    2001-07-01

    This study was designed to investigate the effect of histaminergic agonists and antagonists on the acquisition of vestibular habituation. The experimental animals, pigeons, were subjected to unilateral rotatory and sway habituation training sessions. The habituation of postural reflexes and post-rotatory head nystagmus was assessed. Vestibular habituation in the control group was achieved by adopting the kinetic reflex posture after approximately 9 training sessions, and after 10 and 14 training sessions, respectively for 50% reduction of the total number of beats (TNB) and the duration of post-rotatory head nystagmus. In the sway adaptation test control pigeons needed nearly 15 training sessions while pigeons receiving betahistine adapted after approximately 8 sessions. Administration of histamine and, most notably, betahistine accelerated the process, while both H1 and H2 antagonists (clemastine, cimetidine) tended to retard it, indicating a less significant contribution of H2 receptors. The cholinergic agent physostigmine strongly retarded habituation while the anticholinergic agent scopolamine markedly accelerated it. In addition the adrenomimetic agent ephedrine also accelerated habituation while the adrenolytic agent droperidol retarded reduction of nystagmus beats. The results indicate that histaminergic receptors play a significant role in the vestibular habituation mechanism but are intricately involved with other types of receptors. Betahistine is clearly the agent of choice for attenuating vestibular effects.

  5. Dispersion-optimized optical fiber for high-speed long-haul dense wavelength division multiplexing transmission

    Science.gov (United States)

    Wu, Jindong; Chen, Liuhua; Li, Qingguo; Wu, Wenwen; Sun, Keyuan; Wu, Xingkun

    2011-07-01

    Four non-zero-dispersion-shifted fibers with almost the same large effective area (Aeff) and optimized dispersion properties are realized by novel index profile designing and modified vapor axial deposition and modified chemical vapor deposition processes. An Aeff of greater than 71 μm2 is obtained for the designed fibers. Three of the developed fibers with positive dispersion are improved by reducing the 1550nm dispersion slope from 0.072ps/nm2/km to 0.063ps/nm2/km or 0.05ps/nm2/km, increasing the 1550nm dispersion from 4.972ps/nm/km to 5.679ps/nm/km or 7.776ps/nm/km, and shifting the zero-dispersion wavelength from 1500nm to 1450nm. One of these fibers is in good agreement with G655D and G.656 fibers simultaneously, and another one with G655E and G.656 fibers; both fibers are beneficial to high-bit long-haul dense wavelength division multiplexing systems over S-, C-, and L-bands. The fourth developed fiber with negative dispersion is also improved by reducing the 1550nm dispersion slope from 0.12ps/nm2/km to 0.085ps/nm2/km, increasing the 1550nm dispersion from -4ps/nm/km to -6.016ps/nm/km, providing facilities for a submarine transmission system. Experimental measurements indicate that the developed fibers all have excellent optical transmission and good macrobending and splice performances.

  6. Nonlinear optical responses of multiply ionized noble gases: Dispersion and spin multiplicity effects

    Science.gov (United States)

    Tarazkar, M.; Romanov, D. A.; Levis, R. J.

    2016-07-01

    Dynamic second-order hyperpolarizabilities of atomic noble gases and their multiply ionized ions are computed using ab initio multiconfigurational self-consistent field cubic response theory. For each species, the calculations are performed at wavelengths ranging from the static regime to those about 100 nm above the first multiphoton resonance. The second-order hyperpolarizability coefficients progressively decrease as the electrons are removed from the system, in qualitative agreement with phenomenological calculations. In higher ionization states, the resulting nonlinear refractive index becomes less dispersive as a function of wavelength. At each ionization stage, the sign of the optical response depends on the number of electrons in the system and, if multiple state symmetries are possible, on the spin of the particular quantum state. Thus, for N e3 + and N e4 + , the hyperpolarizability coefficients in the low-spin states (P2u, and S1g, respectively) are positive, while in the high-spin states (S4u, and P3g) they are negative. However, for doubly, triply, and quadruply charged Ar and Kr these coefficients do not undergo a sign change.

  7. Dark soliton interaction in optical time division multiplexed system with randomly varying birefringence and random dispersion map

    Institute of Scientific and Technical Information of China (English)

    Hong Li(李宏); Tiejun Wang(王铁军); Dexiu Huang(黄德修)

    2004-01-01

    Correlated perturbations caused by both randomly varying birefringence and random dispersion map are considered in optical time division multiplexed dispersion-managed dark soliton system, and their effects on soliton interaction are investigated numerically. These perturbations enhance soliton interaction, and their effects relate to the strength of perturbation, separation, and pulse width. The correlation plays an important role and reinforces these effects. Moreover, there is a stochastic limit between two perturbations in the system, where the effect is the largest and the corresponding interaction distance is the shortest.

  8. Theory of dispersive wave frequency shift via trapping by a soliton in an axially nonuniform optical fiber

    DEFF Research Database (Denmark)

    Judge, Alexander C.; Bang, Ole; de Sterke, Martin

    2010-01-01

    We extend the analytical theory explaining the trapping of normally dispersive waves by a Raman soliton in an axially uniform optical fiber to include axially nonuniform fibers. It is shown how a changing group velocity in such a fiber leads to the same trapping mechanism as for a decelerating...... Raman soliton in a uniform fiber. In contrast to this latter case, where the trapping always leads to a blueshift of the confined radiation, the additional design flexibility inherent in the nonuniform geometry permits the redshift of dispersive waves trapped by an accelerating soliton, which itself may...

  9. Study on the 4×10 Gb/s, 400 km dispersion compensation by chirped optical fiber grating

    Institute of Scientific and Technical Information of China (English)

    Li Pei(裴丽); Tigang Ning(宁提纲); Wei Jian(简伟); Tangjun Li(李唐军); Shuisheng Jian(简水生)

    2003-01-01

    In this paper, the dispersion compensation for 4×10 Gb/s, 400 km G.652 fiber by chirped optical fiber Bragg grating (FBG) is introduced. For the first time, we have measured and compensated the polarization mode dispersion (PMD) of FBG, which in each channel is less than 1.1 ps. When the bit error rate (BER) is 10-10 and the bit error is zero, the transmission power penalty of each channel is less than 2 dB, and the best result is negative which means that the receiver sensitivity is increased after transmission.

  10. Dispersive Blow-Up Ⅱ.Schr(o)dinger-Type Equations,Optical and Oceanic Rogue Waves

    Institute of Scientific and Technical Information of China (English)

    Jerry L.BONA; Jean-Claude SAUT

    2010-01-01

    Addressed here is the occurrence of point singularities which owe to the fo-cusing of short or long waves,a phenomenon labeled dispersive blow-up.The context of this investigation is linear and nonlinear,strongly dispersive equations or systems of equa-tions.The present essay deals with linear and nonlinear Schr(o)dinger equations,a class of fractional order SchrSdinger equations and the linearized water wave equations,with and without surface tension. Commentary about how the results may bear upon the formation of rogue waves in fluid and optical environments is also included.

  11. Microstructure and optical dispersion characterization of nanocomposite sol-gel TiO₂-SiO₂ thin films with different compositions.

    Science.gov (United States)

    Kermadi, S; Agoudjil, N; Sali, S; Zougar, L; Boumaour, M; Broch, L; En Naciri, A; Placido, F

    2015-06-15

    Nanocomposite TiO2-SiO2 thin films with different compositions (from 0 to 100 mol% TiO2) were deposited by sol-gel dip-coating method on silicon substrate. Crystal structure, chemical bonding configuration, composition and morphology evolutions with composition were followed by Raman scattering, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy respectively. The refractive index and the extinction coefficient were derived in a broad band wavelength (250-900 nm) from spectroscopic ellipsometry data with high accuracy and correlated with composition and microstructure. Results showed an anatase structure for 100% TiO2 with a grain size in 6-10nm range. Whereas, the inclusion of SiO2 enlarges the optical band gap and suppresses the grain growth up to 4 nm in size. High TiO2 dispersion in SiO2 matrix was observed for all mixed materials. The refractive index (at λ=600 nm) increases linearly with composition from 1.48 (in 100% SiO2) to 2.22 (in 100% TiO2) leading to lower dense material, its dispersion being discussed in terms of the Wemple-DiDomenico single oscillator model. Hence, the optical parameters, such optical dispersion energies E0 and Ed, the average oscillators, strength S0 and wavelength λ0 and the ratio of the carrier concentration to the effective mass N/m(∗) have been derived. The analysis revealed a strong dependence on composition and structure. The optical response was also investigated in term of complex optical conductivity (σ) and both volume and surface energy loss functions (VELF and SELF).

  12. Novel time-of-flight fiber dispersion measurement technique using supercontinuum light sources and acousto-optical tunable filters.

    Science.gov (United States)

    Blume, Niels Göran; Wagner, Steven

    2015-07-20

    Long-distance fiber links require precise knowledge of fiber dispersion characteristics. Similar dispersion characteristics are necessary for supercontinuum broadband laser absorption spectroscopy (SCLAS) to allow proper data evaluation and species concentration determination, as well as numerous other applications. In this work, a time-of-flight approach to measuring the dispersion characteristic of fibers with supercontinuum laser light sources (SCLs) and acousto-optical tunable filters (AOTFs) is presented. Broadband emission of the SCL is filtered with a narrowband AOTF and dispersed in time by the fiber under test. By using the wavelength-specific delay, the dispersion characteristic can be calculated. The technique is especially suited for longer fibers and was verified against a state-of-the-art phase-shift-based dispersion measurement system. Advantages of the new approach include solely utilizing SCLAS system components, as well as a high level of automation and wide spectral coverage, ranging from 1100 to 1700 nm in a single measurement setup.

  13. Improvement of dispersion stability and optical properties of CdSe/ZnSe structured quantum dots by polymer coating.

    Science.gov (United States)

    Kwon, Young-Tae; Eom, Nu Si A; Choi, Yo-Min; Kim, Bum-Sung; Kim, Taek-Soo; Lee, Chan-Gi; Lee, Kun-Jae; Choa, Yong-Ho

    2014-10-01

    In this study, CdSe core and CdSe/ZnSe core/shell quantum dots with a narrow size distribution were synthesized in a micro-reactor. A PMMA coating applied to the surface of CdSe/ZnSe core/shell QDs to prevent degradation gave improved dispersion stability compared to the CdSe core and CdSe/ZnSe core/shell. Many previous approaches to dispersion stability have not been quantitatively assessed. The dispersion stability was confirmed by multiple light scattering measurement. Additionally, the PMMA-coated CdSe/ZnSe QDs showed greatly improved optical properties with a photoluminescence quantum yield up to 80%. This structural motif is expected to prevent the degradation of QDs.

  14. Imaging internal flows in a drying sessile polymer dispersion drop using Spectral Radar Optical Coherence Tomography (SR-OCT).

    Science.gov (United States)

    Manukyan, Selin; Sauer, Hans M; Roisman, Ilia V; Baldwin, Kyle A; Fairhurst, David J; Liang, Haida; Venzmer, Joachim; Tropea, Cameron

    2013-04-01

    In this work, we present the visualization of the internal flows in a drying sessile polymer dispersion drop on hydrophilic and hydrophobic surfaces with Spectral Radar Optical Coherence Tomography (SR-OCT). We have found that surface features such as the initial contact angle and pinning of the contact line, play a crucial role on the flow direction and final shape of the dried drop. Moreover, imaging through selection of vertical slices using optical coherence tomography offers a feasible alternative compared to imaging through selection of narrow horizontal slices using confocal microscopy for turbid, barely transparent fluids.

  15. Compact optical true time delay beamformer for a 2D phased array antenna using tunable dispersive elements.

    Science.gov (United States)

    Ye, Xingwei; Zhang, Fangzheng; Pan, Shilong

    2016-09-01

    A hardware-compressive optical true time delay architecture for 2D beam steering in a planar phased array antenna is proposed using fiber-Bragg-grating-based tunable dispersive elements (TDEs). For an M×N array, the proposed system utilizes N TDEs and M wavelength-fixed optical carriers to control the time delays. Both azimuth and elevation beam steering are realized by programming the settings of the TDEs. An experiment is carried out to demonstrate the delay controlling in a 2×2 array, which is fed by a wideband pulsed signal. Radiation patterns calculated from the experimentally measured waveforms at the four antennas match well with the theoretical results.

  16. Generation and Stability Analysis of Self Similar Pulses Through Dispersion Tailored Passive Microstructured Optical Fibers in Mid Infrared Regime

    CERN Document Server

    Biswas, Piyali; Biswas, Abhijit; Ghosh, Somnath

    2015-01-01

    We report a numerical study on generation and stability of a parabolic pulse during its propagation through a highly nonlinear specialty optical fiber. Here, we have generated a parabolic pulse at 2.1 $\\mu$m wavelength from a Gaussian input pulse with 1.9 ps FWHM and 75 W peak power after travelling through only 20 cm length of a chalcogenide glass based microstructured optical fiber (MOF). The stability of such a parabolic pulse has been analyzed by introducing a variable loss profile within the loss window of the MOF. Moreover, three different dispersion regimes of propagation have been considered to achieve most stable propagation of the pulse.

  17. Energy exchange between (3+1)D colliding spatiotemporal optical solitons in dispersive media with cubic-quintic nonlinearity

    Institute of Scientific and Technical Information of China (English)

    Yang Hong; Tang Yi

    2008-01-01

    We investigate the energy exchange between (3+1)D colliding spatiotemporal solitons (STSs) in dispersive media with cubic-quintic (CQ) nonlinearity by numerical simulations. Energy exchange between two (3+l)D head on colliding STSs caused by their phase difference is observed, just as occurring in other optical media. Moreover, energy exchange between two head-on colliding STSs with different speeds is firstly shown in the CQ and saturable media.This phenomenon, we believe, may arouse some interest in the future studies of soliton collision in optical media.

  18. A Comparison between Electrical and Optical Chromatic Dispersion Compensation in Wavelength Divison Multiplexing Network Regarding to Electrical Pulse Shapes

    Directory of Open Access Journals (Sweden)

    Mohammad S. Ab-Rahman

    2012-01-01

    Full Text Available Problem statement: Besides of some impairment that has been inherited form single channel, specialists confronted with new obstacles in WDM implementation which bared them for achieving desired performance. Although Chromatic Dispersion (CD exists in single channel too, it can worsens new nonlinearities which are occurs just in WDM systems. So CD compensation in WDM is even more vital than single channel one. Approach: A wide range of optical and electrical CD compensation techniques have been represented. In this study we evaluate the efficiency of feed Forward-Decision Feedback Equalizer (FFE-DFE as one type of electrical compensation methods and Dispersion Compensation Fiber as one type of optical compensator. Also we will look how electrical pulse shapes induced by pulse generator in transmitter, can impact on the performance of the either optical or electrical compensations. Results: After implementation, it was revealed that overall optical compensation with DCF gives us better performance than electrical equalizer and NRZ is more vulnerable than two other pulse shapes. Conclusion: Chromatic compensation was implemented with different pulse shapes and RZ pulse shape with optical compensation showed the best performance.

  19. Flat Supercontinuum Generated in a Single-Mode Optical Fibre with a New Chromatic Dispersion Profile

    Institute of Scientific and Technical Information of China (English)

    XU Yong-Zhao; REN Xiao-Min; ZHANG Xia; HUANG Yong-Qing; XU Wen-Cheng

    2005-01-01

    @@ A new chromatic dispersion profile of a single-mode opticalfibre is proposed for generating a supercontinuum with a flatly broadened spectrum. The chromatic dispersion D( λ, z) is a convex function of wavelengths and has no zero-dispersion wavelengths over the whole part of thefibre as D(λ, z) is negative. It is shown that the flat supercontinuum spectrum is obtained when the pump wavelength is set in the vicinity of the wavelength at which the peak chromatic dispersion is near zero and the strong residual pump component is eliminated.

  20. A comparative in vitro efficacy of conventional rotatory and chemomechanical caries removal: Influence on cariogenic flora, microhardness, and residual composition

    Directory of Open Access Journals (Sweden)

    Rene Garcia-Contreras

    2014-01-01

    Full Text Available Background: Chemomechanical caries removal system is part of the minimal invasive dentistry; the aim of the study was to compare the amount of bacteria after caries removal with chemomechanical system and conventional rotatory instruments and to test the Vickers microhardness and micro-RAMAN analysis of residual dentin after excavation. Materials and Methods: Molars were induced for demineralization, confirmed with DIAGNOdent; Streptococcus mutans were inoculated into the cavities and filled. Caries removal was performed with rotatory instruments and chemomechanical system; surviving bacteria were cultured for 24 and 48 hours at 37΀C. Vickers microhardness and micro-RAMAN analysis were tested after excavation. Data were analyzed with Wilcoxon, continuity correction, odds ratio, ANOVA post hoc Tukey test, and Spearman correlation. Results: Demineralization was significantly detectable at 240 hours of incubation; conventional rotatory instruments and chemomechanical caries removal were effective in 19.4%-22.6% and 25.8%-32.3%, respectively. Vickers microhardness of chemomechanical system was higher (P < 0.0001 than conventional rotatory instruments and comparable to healthy dentin. Micro-RAMAN analysis showed that healthy dentin is correlated to chemomechanical system (R 2 = 0.683, P < 0.00001 and drilling with burs (R 2 = 0.139, P < 0.00001. Conclusion: The chemomechanical system is effective for caries elimination, comparable to conventional rotatory instruments; the remaining Vickers microhardness and composition surface tissue are similar to healthy dentin.

  1. A comparative in vitro efficacy of conventional rotatory and chemomechanical caries removal: Influence on cariogenic flora, microhardness, and residual composition

    Science.gov (United States)

    Garcia-Contreras, Rene; Scougall-Vilchis, Rogelio Jose; Contreras-Bulnes, Rosalia; Sakagami, Hiroshi; Morales-Luckie, Raul Alberto; Nakajima, Hiroshi

    2014-01-01

    Background: Chemomechanical caries removal system is part of the minimal invasive dentistry; the aim of the study was to compare the amount of bacteria after caries removal with chemomechanical system and conventional rotatory instruments and to test the Vickers microhardness and micro-RAMAN analysis of residual dentin after excavation. Materials and Methods: Molars were induced for demineralization, confirmed with DIAGNOdent; Streptococcus mutans were inoculated into the cavities and filled. Caries removal was performed with rotatory instruments and chemomechanical system; surviving bacteria were cultured for 24 and 48 hours at 37°C. Vickers microhardness and micro-RAMAN analysis were tested after excavation. Data were analyzed with Wilcoxon, continuity correction, odds ratio, ANOVA post hoc Tukey test, and Spearman correlation. Results: Demineralization was significantly detectable at 240 hours of incubation; conventional rotatory instruments and chemomechanical caries removal were effective in 19.4%-22.6% and 25.8%-32.3%, respectively. Vickers microhardness of chemomechanical system was higher (P < 0.0001) than conventional rotatory instruments and comparable to healthy dentin. Micro-RAMAN analysis showed that healthy dentin is correlated to chemomechanical system (R2 = 0.683, P < 0.00001) and drilling with burs (R2 = 0.139, P < 0.00001). Conclusion: The chemomechanical system is effective for caries elimination, comparable to conventional rotatory instruments; the remaining Vickers microhardness and composition surface tissue are similar to healthy dentin. PMID:25506140

  2. Spontaneous natural optical activity in disordered media

    CERN Document Server

    Pinheiro, F A; Papasimakis, N; Zheludev, N I

    2016-01-01

    We demonstrate natural optical activity in disordered ensembles of non-chiral plasmonic resonators. We show that the statistical distributions of rotatory power and spatial dichroism are strongly dependent on the scattering mean free path in diffusive random media. This result is explained in terms of the intrinsic geometric chirality of disordered media, as they lack mirror symmetry. We argue that chirality and natural optical activity of disordered systems can be quantified by the standard deviation of both rotatory power and spatial dichroism. Our results are based on microscopic electromagnetic wave transport theory coupled to vectorial Green's matrix method for pointlike scatterers, and are independently confirmed by full-wave simulations.

  3. Polarization modulational instability in a birefringent optical fiber with fourth order dispersion

    Indian Academy of Sciences (India)

    R Ganapathy; V C Kuriakose

    2001-10-01

    We obtain conditions for the occurrence of polarization modulational instability in the anomalous and normal dispersion regimes for the coupled nonlinear Schrödinger equation modelling fourth order dispersion effects when the linearly polarized pump is oriented at arbitrary angles with respect to the slow and fast axes of the birefringent fiber.

  4. Hyperbolic shock waves of the optical self-focusing with normal group-velocity dispersion

    DEFF Research Database (Denmark)

    Bergé, L.; Germaschewski, K.; Grauer, R.

    2002-01-01

    The theory of focusing light pulses in Kerr media with normal group-velocity dispersion in (2+1) and (3+1) dimensions is revisited. It is shown that pulse splitting introduced by this dispersion follows from shock fronts that develop along hyperbolas separating the region of transverse self...

  5. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  6. Controllable vacuum-induced diffraction of matter-wave superradiance using an all-optical dispersive cavity

    Science.gov (United States)

    Su, Shih-Wei; Lu, Zhen-Kai; Gou, Shih-Chuan; Liao, Wen-Te

    2016-10-01

    Cavity quantum electrodynamics (CQED) has played a central role in demonstrating the fundamental principles of the quantum world, and in particular those of atom-light interactions. Developing fast, dynamical and non-mechanical control over a CQED system is particularly desirable for controlling atomic dynamics and building future quantum networks at high speed. However conventional mirrors do not allow for such flexible and fast controls over their coupling to intracavity atoms mediated by photons. Here we theoretically investigate a novel all-optical CQED system composed of a binary Bose-Einstein condensate (BEC) sandwiched by two atomic ensembles. The highly tunable atomic dispersion of the CQED system enables the medium to act as a versatile, all-optically controlled atomic mirror that can be employed to manipulate the vacuum-induced diffraction of matter-wave superradiance. Our study illustrates a innovative all-optical element of atomtroics and sheds new light on controlling light-matter interactions.

  7. Precise parallel optical spectrum analysis using the advanced two-phonon light scattering combined with the cross-disperser technique.

    Science.gov (United States)

    Shcherbakov, A S; Arellanes, A O; Chavushyan, V

    2016-12-01

    We develop an advanced approach to the optical spectrometer with acousto-optical dynamic grating for the Guillermo Haro astrophysical observatory (Mexico). The progress consists of two principle novelties. First is the use of the acousto-optical nonlinearity of two-phonon light scattering in crystals with linear acoustic losses. This advanced regime of light scattering exhibits a recently revealed additional degree of freedom, which allows tuning of the frequency of elastic waves and admits the nonlinear apodization improving the dynamic range. The second novelty is the combination of the cross-disperser with acousto-optical processing. A similar pioneering step provides an opportunity to operate over all the visible range in a parallel regime with maximal achievable resolution. The observation window of the optical spectrometer in that observatory is ∼9  cm, so that the theoretical estimations of maximal performances for a low-loss LiNbO3 crystal for this optical aperture at λ=405  nm give spectral resolution of 0.0523 Å, resolving power of 77,400, and 57,500 spots. The illustrative proof-of-principle experiments with a 6 cm LiNbO3 crystal have been performed.

  8. Simultaneous dispersion and non-linearity compensation with mid-span optical phase conjugation and distributed Raman amplifier for a sub-carrier multiplexed optical transmission link

    Science.gov (United States)

    Chandra, S.; Vardhanan, A. Vishnu; Gangopadhyay, R.

    2007-11-01

    Optical phase conjugation (OPC) and distributed Raman amplifier (DRA) combination (OPC-DRA) is demonstrated as a potential enabling solution for simultaneous reduction of fiber non-linearities and dispersion compensation of a sub-carrier multiplexed (SCM) optical transmission link. The present work is focused on the use of OPC-DRA combination for system performance improvement in terms of composite second order distortion (CSO) and carrier to noise ratio (CNR) of the SCM link. The analysis further shows that, introduction of DRA with proper pumping scheme significantly reduce fiber non-linearity resulting in improvement of the system performance in terms of CNR, compared to the situation where only mid-way optical phase conjugation is used.

  9. Demonstration of all-optical phase noise suppression scheme using optical nonlinearity and conversion/dispersion delay.

    Science.gov (United States)

    Chitgarha, Mohammad Reza; Khaleghi, Salman; Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Almaiman, Ahmed; Daab, Wajih; Rogawski, Devora; Tur, Moshe; Touch, Joseph D; Langrock, Carsten; Fejer, Martin M; Willner, Alan E

    2014-05-15

    We propose and demonstrate an all-optical phase noise reduction scheme that uses optical nonlinear mixing and tunable optical delays to suppress the low-speed phase noise induced by laser linewidth. By utilizing the phase conjugate copy of the original signal and two narrow-linewidth optical pumps, the phase noise induced by laser linewidth can be reduced by a factor of ∼5 for a laser with 500-MHz phase noise bandwidth. The error-vector-magnitude can be improved from ∼30% to ∼14% for the same laser linewidth for 40-Gbit/s quadrature phase shift keying signal.

  10. 80-Gb/s wavelength conversion based on cross-phase modulation in high-nonlinearity dispersion-shifted fiber and optical filtering

    DEFF Research Database (Denmark)

    Yu, Jianjun; Jeppesen, Palle

    2001-01-01

    Using cross-phase modulation in a 1-km high-nonlinearity dispersion-shifted fiber with subsequent filtering by a tunable optical filter, 80-Gb/s pulsewidth maintained wavelength conversion is realized. Penalty-free transmission over 80-km conventional single-mode fiber and 12-km dispersion...

  11. Theoretical Calculation of System Performance of Fiber Optic Network with Chromatic Dispersion, Polarization Mode Dispersion, Polarization Dependent Loss, and Amplifier Spontaneous Emission Noise

    Science.gov (United States)

    Abuzariba, Suad Mohamed

    This thesis includes a theoretical study of the performance of an optical network system with linear impairments: chromatic dispersion (CD), polarization mode dispersion (PMD), polarization dependent loss (PDL), and amplified spontaneous emission (ASE) noise. Both the a-factor and bit error rate (BER) were used as performance parameters in this study. First, an analytical optical eye diagram evaluation for a system of highly mode coupled PMD/PDL fiber and lumped sections (up to fifteen sections) have been presented in this study. Based on this evaluation we found that with PDL considered as well as PMD, the a-factor of the output becomes higher than that of a Maxwellian fiber having the same total root mean-squared PMD and PDL values, when the mean-square PDL element of the lumped sections makes up the major portion of the total mean-square of the whole system. Whereas without considering PDL, the a-factor becomes higher as the mean-square PMD element of the Maxwellian fiber takes the major portion of the total mean-square PMD element of the whole system. Also the worst case for the a-factor occurred when the lumped sections were in the middle between two equivalent Maxwellian fibers, rether than if the lumped sections were followed by Maxwellian fiber or the Maxwellian fiber is followed by the lumped sections. We also note that two equivalent Maxwellian fibers connected in series will not give the same a-factor as a Maxwellian fiber equivalent calculated by concatenation rules unless they have the same values of PMD, PDL, and polarization direction correlation elements. Second, considering ASE-noise besides CD, PMD, and PDL, improved values of bit error rate (BER) were gotten using the moment generation function for the optical system in cases of ON-OFF modulation format and DPSK modulation format. We found that, even when considering the noise only without the signal, the probability density function of the output current was dependent on the output state of

  12. Effects of cation compositions on the electronic properties and optical dispersion of indium zinc tin oxide thin films by electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Denny, Yus Rama [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Seo, Soonjoo [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-806 (Korea, Republic of); Lee, Kangil; Oh, Suhk Kun [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Kang, Hee Jae, E-mail: hjkang@cbu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Heo, Sung; Chung, Jae Gwan; Lee, Jae Cheol [Analytical Engineering Center, Samsung Advanced Institute of Technology, Suwon 440-600 (Korea, Republic of); Tougaard, Sven [Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M. (Denmark)

    2015-02-15

    Highlights: • REELS analysis can provide optical dispersion and electronic properties of oxide materials. • The band gap varied with In/Zn/Sn compositions and increased after annealing. • The optical properties were examined using REELS in conjunction with the Tougaard–Yubero model. • The dispersion parameters were determined by a single-oscillator Wemple–DiDomenico model. • The Zn and Sn contents play a crucial role in determining the single-oscillator constant and dispersion energy of IZTO thin films. - Abstract: The electronic properties and optical dispersion of indium zinc tin oxide (IZTO) films with different cation compositions were investigated by reflection electron energy loss spectroscopy (REELS). The REELS spectra of IZTO films revealed that the band gap varied with different Sn/Zn ratios and In content. The optical properties were examined with REELS data using Tougaard–Yubero model and the results were compared with the envelope of the transmission spectra obtained using a UV-spectrometer. The dispersion behavior of the refractive index from REELS results was studied in terms of the single-oscillator Wemple–DiDomenico model. The results showed that the different compositions of In/Zn/Sn caused a change in the dispersion parameters of IZTO thin films in contrast to the static values of refractive indices and dielectric constant which remained the same. Our work demonstrated that REELS is an efficient tool to study the optical properties of a material by obtaining the optical parameters.

  13. Transmission test in connection of different types of optical fibers: a dispersion-shifted single-mode optical fiber (DSF) and a single-mode optical fiber (SM); DSF-SM ishu hikari fiber setsuzoku ni okeru denso shiken

    Energy Technology Data Exchange (ETDEWEB)

    Uemura, J. [Chugoku Electric Power Co. Inc., Hiroshima (Japan)

    1998-08-25

    The currently used optical transmission system usually uses a single-mode optical fiber (SM) with 1.3 {mu} m band. For sections requiring long-distance transmission, a dispersion-shifted single-mode optical fiber (DSF) with 1.55 {mu} m band is beginning to be partly used. If, in using these fibers, the different types of optical fibers, SM and DSF, can be used directly connected with each other, structuring an economical optical communication network including the existing SM fibers may become possible. This paper describes measurements of connection loss between the different optical fibers of DSF and SM, a transmission test on the connection between the different optical fibers of DSF and SM by using an amplifier for optical fibers used in an actual field, and an optical wave multiplex transmission test. The measurements and the tests were carried out in winter and summer of 1997 by using the existing OPGW optical fibers among the Okayama substation, the Higashi-Okayama substation, and the Susai substation. The connection between the different optical fibers of DSF and SM generates greater connection loss than in connection with the same type of fibers due to difference in the mode field diameters. Therefore, it will be necessary in constituting an optical fiber line to incorporate connection loss of about 1 to 2 dB in connector connection and about 0.5 to 1 dB in welding connection. 1 ref., 17 figs., 7 tabs.

  14. Variational principles for dissipative (sub)systems, with applications to the theory of dispersion and geometrical optics

    CERN Document Server

    Dodin, I Y; Ruiz, D E

    2016-01-01

    Applications of variational methods are typically restricted to conservative systems. Some extensions to dissipative systems have been reported too but require ad hoc techniques such as artificial doubling of variables. Here, a different approach is proposed. We show that, for a broad class of dissipative systems of practical interest, variational principles can be formulated using constant Lagrange multipliers and Lagrangians nonlocal in time, which allow treating reversible and irreversible dynamics on the same footing. A general variational theory of linear dispersion is formulated as an example. In particular, we present a variational formulation for linear geometrical optics in a general dissipative medium, which is allowed to be nonstationary, inhomogeneous, nonisotropic, and exhibit both temporal and spatial dispersion simultaneously.

  15. Variational principles for dissipative (sub)systems, with applications to the theory of linear dispersion and geometrical optics

    Science.gov (United States)

    Dodin, I. Y.; Zhmoginov, A. I.; Ruiz, D. E.

    2017-04-01

    Applications of variational methods are typically restricted to conservative systems. Some extensions to dissipative systems have been reported too but require ad hoc techniques such as the artificial doubling of the dynamical variables. Here, a different approach is proposed. We show that, for a broad class of dissipative systems of practical interest, variational principles can be formulated using constant Lagrange multipliers and Lagrangians nonlocal in time, which allow treating reversible and irreversible dynamics on the same footing. A general variational theory of linear dispersion is formulated as an example. In particular, we present a variational formulation for linear geometrical optics in a general dissipative medium, which is allowed to be nonstationary, inhomogeneous, anisotropic, and exhibit both temporal and spatial dispersion simultaneously.

  16. Optimal Design of Dual-Pump Fibre-Optical Parametric Amplifiers with Dispersion Fluctuations Based on Hybrid Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    LIU Xue-Ming; LI Yan-He

    2005-01-01

    @@ Solutions of dual-pump fibre-optical parametric amplifiers (DP-FOPAs) with dispersion fluctuations are derived by using a matrix operator. Based on these solutions and a hybrid genetic algorithm, we have optimized threesection DP-FOPAs to increase the signal band and improve the gain uniformity. The optimizations demonstrate that when dispersion fluctuations are taken into account, the 44-nm signal band with the 0.37-dB ripple and over 14.8-dB gain can be obtained from the three-section DP-FOPA, instead of the lowest gain of ~13dB with the ripple of more than 15dB from the single-section DP-FOPA.

  17. Effects of oxygen partial pressure and annealing on dispersive optical nonlinearity in NiO thin films

    Science.gov (United States)

    Chouhan, Romita; Baraskar, Priyanka; Agrawal, Arpana; Gupta, Mukul; Sen, Pranay K.; Sen, Pratima

    2017-07-01

    We report annealing induced sign reversal of dispersive optical nonlinearity in ion beam sputtered NiO thin films deposited at 30% and 70% oxygen partial pressures. In the Ultraviolet-visible spectra of the samples, the transmission peak corresponding to d-d transitions is observed near 2 eV. A shift in this peak towards higher energy was observed when the same films were annealed at 523 K. The near resonant photoinduced transitions produced giant nonlinear optical susceptibilities of both third- and fifth- orders when the annealed film was irradiated by a continuous wave 632.8 nm He-Ne laser. The role of the thermo-optic effect has been examined critically. Experimental studies further reveal that the oxygen partial pressure influences the growth direction of the grains in the thin films. The well known Z-scan experimental procedure has been followed for measurements of optical nonlinearities in all the NiO films. The nonlinear refractive indices of both the as-deposited and annealed NiO thin films are defined in terms of the thermo-optic coefficients (d/nd T ) T =T0 and (d/2nd T2 ) T =T0 .

  18. Determination and analysis of dispersive optical constants of CuIn{sub 3}S{sub 5} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khemiri, N., E-mail: naoufel_khemiri@yahoo.f [Laboratoire de Photovoltaique et Materiaux Semiconducteurs-ENIT, Universite Tunis, ElManar BP 37, Le belvedere, 1002 Tunis (Tunisia); Sinaoui, A.; Kanzari, M. [Laboratoire de Photovoltaique et Materiaux Semiconducteurs-ENIT, Universite Tunis, ElManar BP 37, Le belvedere, 1002 Tunis (Tunisia)

    2011-04-15

    CuIn{sub 3}S{sub 5} thin films were prepared from powder by thermal evaporation under vacuum (10{sup -6} mbar) onto glass substrates. The glass substrates were heated from 30 to 200 {sup o}C. The films were characterized for their optical properties using optical measurement techniques (transmittance and reflectance). We have determined the energy and nature of the optical transitions of films. The optical constants of the deposited films were determined in the spectral range 300-1800 nm from the analysis of transmission and reflection data. The Swanepoel envelope method was employed on the interference fringes of transmittance patterns for the determination of variation of refractive index with wavelength. Wemple-Di Domenico single oscillator model was applied to determine the optical constants such as oscillator energy E{sub 0} and dispersion energy E{sub d} of the films deposited at different substrate temperatures. The electric free carrier susceptibility and the ratio of the carrier concentration to the effective mass were estimated according to the model of Spitzer and Fan.

  19. Influence of Rotation Increments on Imaging Performance for a Rotatory Dual-Head PET System

    Directory of Open Access Journals (Sweden)

    Fanzhen Meng

    2017-01-01

    Full Text Available For a rotatory dual-head positron emission tomography (PET system, how to determine the rotation increments is an open problem. In this study, we simulated the characteristics of a rotatory dual-head PET system. The influences of different rotation increments were compared and analyzed. Based on this simulation, the imaging performance of a prototype system was verified. A reconstruction flowchart was proposed based on a precalculated system response matrix (SRM. The SRM made the relationships between the voxels and lines of response (LORs fixed; therefore, we added the interpolation method into the flowchart. Five metrics, including spatial resolution, normalized mean squared error (NMSE, peak signal-to-noise ratio (PSNR, contrast-to-noise (CNR, and structure similarity (SSIM, were applied to assess the reconstructed image quality. The results indicated that the 60° rotation increments with the bilinear interpolation had advantages in resolution, PSNR, NMSE, and SSIM. In terms of CNR, the 90° rotation increments were better than other increments. In addition, the reconstructed images of 90° rotation increments were also flatter than that of 60° increments. Therefore, both the 60° and 90° rotation increments could be used in the real experiments, and which one to choose may depend on the application requirement.

  20. A diagnose not to miss: Rotatory Atlantoaxial subluxation in emergency service

    Directory of Open Access Journals (Sweden)

    Umut OCAK

    2016-03-01

    Full Text Available Objective: The objective of this study is to take attention to atlantoaxial subluxations especially in pediatric population that may be misdiagnosed in the emergency services easily. When diagnosed early in the emergency services, it may be corrected with ease and the treatment is more likely to be conservative. Method: Seven patients with atlantoaxial rotatory subluxation (AARS, between ages of 5 and 13, who admitted to our emergency service between 1 July 2013 - 1 September 2014 were examined retrospectively. Results: All patients were treated conservatively with bed rest, muscle relaxants and rigid cervical collar. None of them needed surgery. Conclusions: Atlantoaxial rotatory subluxation (AARS is one of the main types of cervical spine anomalies seen in pediatric patients and is a rare condition that is often misdiagnosed and therefore incorrectly managed especially in emergency services. The diagnosis requires a high index of suspicion. Many pediatric cervical spine injuries can be treated with external immobilization and AARS is almost always reducible. Pediatric population is prone to upper spine injuries due to ligamentous laxity and AARS should always be kept in mind especially in emergency services.

  1. Structure, optical spectroscopy and dispersion parameters of ZnGa2Se4 thin films at different annealing temperatures

    Science.gov (United States)

    Fadel, M.; Yahia, I. S.; Sakr, G. B.; Yakuphanoglu, F.; Shenouda, S. S.

    2012-06-01

    Thin films of ZnGa2Se4 were deposited by thermal evaporation method of pre-synthesized ingot material onto highly cleaned microscopic glass substrates. The chemical composition of the investigated compound thin film form was determined by means of energy-dispersive X-ray spectroscopy. X-ray diffraction XRD analysis revealed that the powder compound is polycrystalline and the as-deposited and the annealed films at Ta = 623 and 673 K have amorphous phase, while that annealed at Ta = 700 K is polycrystalline with a single phase of a defective chalcopyrite structure similar to that of the synthesized material. The unit-cell lattice parameters were determined and compared with the reported data. Also, the crystallite size L, the dislocation density δ and the main internal strain ɛ were calculated. Analyses of the AFM images confirm the nanostructure of the prepared annealed film at 700 K. The refractive index n and the film thickness d were determined from optical transmittance data using Swanepoel's method. It was found that the refractive index dispersion data obeys the single oscillator model from which the dispersion parameters were determined. The electric susceptibility of free carriers and the carrier concentration to the effective mass ratio were determined according to the model of Spitzer and Fan. The analysis of the optical absorption revealed both the indirect and direct energy gaps. The indirect optical gaps are presented in the amorphous films (as-deposited, annealed at 623 and 673 K), while the direct energy gap characterized the polycrystalline film at 700 K. Graphical representations of ɛ1, ɛ2, tan δ, - Im[1/ɛ*] and - Im[(1/ɛ* + 1)] are also presented. ZnGa2Se4 is a good candidate for optoelectronic and solar cell devices.

  2. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  3. Electro-optical determination of the constant electric dipole of disperse particles by the method of crossed electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Voitylov, V.V.; Spartakov, A.A.; Tolstoi, N.A.; Trusov, A.A.; Boitsova, I.N. [St. Petersburg State Univ. (Russian Federation)

    1995-04-01

    An electro-optical method of crossed electric fields is proposed for determining constant dipole colloidal particles moments of colloidal particles. Fields of this type make it possible to study the motion of colloidal particles determined exclusively by their constant moments, which substantially improves the measurement accuracy of these moments. This is of particular importance for the investigation of colloidal particles with constant dipole moments less than or comparable to induced dipole moments. For a number of disperse systems, the constant dipole moments per unit area of particles are determined. It is shown that the values of these specific moments are close to each other.

  4. Laser pulse amplification and dispersion compensation in an effectively extended optical cavity containing Bose-Einstein condensates

    OpenAIRE

    Sennaroğlu, Alphan; Müstecaplıoğlu, Özgür Esat; Tarhan, D.

    2013-01-01

    Laser pulse amplification and dispersion compensation in effectively extended optical cavity containing Bose-Einstein condensates D Tarhan1, A Sennaroglu2, ¨O E M¨ustecaplıo˘glu2 1Harran University, Department of Physics, 63300, S¸anlıurfa, Turkey 2Ko¸c University, Department of Physics, 34450, Sarıyer, Istanbul, Turkey E-mail: Abstract. We review and critically evaluate our proposal of a pulse amplification scheme based on two Bose-Einstein cond...

  5. Optical and Structural Investigation of CdSe Quantum Dots Dispersed in PVA Matrix and Photovoltaic Applications

    OpenAIRE

    Pallabi Phukan; Dulen Saikia

    2013-01-01

    CdSe quantum dots (QDs) dispersed in polyvinyl alcohol (PVA) matrix with their sizes within the quantum dot regime have been synthesized via a simple heat induced thermolysis technique. The effect of the concentrations of the cadmium source on the optical properties of CdSe/PVA thin films was investigated through UV-Vis absorption spectroscopy. The structural analysis and particle size determination as well as morphological studies of the CdSe/PVA nanocomposite thin films were done with the h...

  6. First-Order-Like Phase Transition Induced by Two Different Kinds of Noise in Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HEYing; ZHUShi-Qun

    2003-01-01

    With unified colored noise approximation, the steady state distribution function in dispersive optical bistability including both intensity and phase fluctuations is obtained. The parameter plane of the first-order-like phase transition is a/so derived with numerical method. It is found that the number of extremes at non-zero values of the output field in the steady state distribution function is changed from zero, two to four. It is shown that the strengths of the intensity fluctuation and the phase fluctuation have great effect on the first-order-fike phase transition.

  7. Effects of walk-off on cross-phase modulation induced modulation instability in an optical fibre with high-order dispersion

    Institute of Scientific and Technical Information of China (English)

    Zhong Xian-Qiong; Xiang An-Ping

    2007-01-01

    This paper investigates the effects of walk-off among optical pulses on cross-phase modulation induced modulation instability in the normal dispersion region of an optical fibre with high-order dispersion. The results indicate that, in the case of high-order dispersion, the walk-off effect takes on new characteristics and will influence considerably the shape, position and especially the number of the spectral regions of the gain spectra of modulation instability. Not only the group-velocity mismatch, but also the difference of the third-order dispersion of two optical waves will alter the gain spectra of modulation instability but in different ways. Depending on the values of the walk-off parameters, the number of the spectral regions may increase from two to at most four, and the spectral shape and position may change too.

  8. Influence of the interface corrugation on the subband dispersions and the optical properties of (113)-oriented GaAs/AlAs superlattices

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Lüerssen, D.; Kalt, H.;

    1996-01-01

    We report on the influence of the interface corrugation in (113)-grown GaAs/AlAs superlattices on their band-edge optical properties both in theory and experiment. We calculate the subband dispersions and the optical anisotropies in a multiband k . p formalism. The dominating contribution to the ...

  9. Faraday色散光学滤波器的研究进展%The Research Advance of Faraday Dispersion Optical Filter

    Institute of Scientific and Technical Information of China (English)

    贾晓玲; 掌蕴东; 王骐

    2001-01-01

    本文综述了Faraday反常色散光学滤波器的国内外研究进展,并提出发展前景。%This paper summarized the international and domestic developmentof Faraday anomalous dispersion optical filters in detail. Meanwhile,the prospect of the optical filter was also analyzed.

  10. Effect of solution molarity on optical dispersion energy parameters and electrochromic performance of Co3O4 films

    Science.gov (United States)

    Dhas, C. Ravi; Venkatesh, R.; Sivakumar, R.; Raj, A. Moses Ezhil; Sanjeeviraja, C.

    2017-10-01

    Co3O4 films were deposited on glass and FTO (F:SnO2) substrates by different solution molarities (0.05-0.20 M) through nebulizer spray technique. The crystalline quality of the films was evaluated by X-ray diffraction. The morphological variation of Co3O4 films for different solution concentration was observed from scanning electron microscopy. Optical constants (n and k) and dispersion energy parameters were calculated by fitting the transmittance curves using Swanepoel envelope method. The electrical parameters such as sheet resistance and activation energy were estimated using four probe method. The electrochromic performance of the films was analyzed by electrochemical measurements such as cyclic voltammetry, chronoamperometry, chronocoulometry and optical contrast studies.

  11. Dielectric and electro-optical properties of polymer-stabilized liquid crystal. II. Polymer PiBMA dispersed in MBBA

    Science.gov (United States)

    Tripathi, Pankaj Kumar; Pande, Mukti; Singh, Shri

    2016-09-01

    In continuation of our earlier work (Pande et al. in Appl Phys A 122:217-226, 2016), we report the results of dielectric and electro-optical properties of pure MBBA and PSLC (polymer PiBMA dispersed in MBBA) systems. The polymer networks domains formed are found to be anisotropic and are oriented in the direction of electric field for both the planar and homeotropic alignment cells. The dielectric anisotropy, optical anisotropy, response time, threshold voltage, splay elastic constant and rotational viscosity were observed for both the LC and PSLC systems with electric field. The liquid crystal properties are affected significantly with increasing concentration of polymer in pure LC material. It has been observed that the polymer networks interaction plays a major role in changing the properties of PSLC system. The effect of dielectric loss and dielectric permittivity on both pure LC and PSLC systems is also discussed.

  12. Optical tweezers in concentrated colloidal dispersions : Manipulating and imaging individual particles

    NARCIS (Netherlands)

    Vossen, Dirk Leo Joep

    2004-01-01

    Using a laser beam that is focused down to a diffraction-limited spot, particles with a size ranging from several nanometers up to tens of micrometers can be trapped and manipulated. This technique, known as "optical tweezers" or "optical trapping", has been used in a wide variety of (interdisciplin

  13. Optical tweezers in concentrated colloidal dispersions : Manipulating and imaging individual particles

    NARCIS (Netherlands)

    Vossen, Dirk Leo Joep

    2004-01-01

    Using a laser beam that is focused down to a diffraction-limited spot, particles with a size ranging from several nanometers up to tens of micrometers can be trapped and manipulated. This technique, known as "optical tweezers" or "optical trapping", has been used in a wide variety of

  14. Relativistic regimes for dispersive shock-waves in non-paraxial nonlinear optics

    CERN Document Server

    Gentilini, Silvia; Conti, Claudio

    2014-01-01

    We investigate the effect of non-paraxiality in the dynamics of dispersive shock waves in the defocusing nonlinear Schroedinger equation. We show that the problem can be described in terms of a relativistic particle moving in a potential. Lowest order corrections enhance the wave-breaking and impose a limit to the highest achievable spectrum in an amount experimentally testable.

  15. Dispersion Studies on Multimode Polymer Spiral Waveguides for Board-Level Optical Interconnects

    CERN Document Server

    Chen, Jian; Edwards, Tom J; Brown, Christian T A; Penty, Richard V; White, Ian H

    2016-01-01

    Dispersion studies are conducted on 1m long multimode polymer spiral waveguides with different refractive index profiles. Bandwidth-length products >40GHzxm are obtained from such waveguides under a 50/125 um MMF, indicating the potential of this technology.

  16. New Optical Solitons in High-Order Dispersive Cubic-Quintic Nonlinear Schrodinger Equation

    Institute of Scientific and Technical Information of China (English)

    LI Hua-Mei; XU You-Shen; LIN Ji

    2004-01-01

    By using the generalized tanh-function method, we find bright and dark solitary wave solutions to an extended nonlinear Schrodinger equation with the third-order and fourth-order dispersion and the cubic-quintic nonlinear terms, describing the propagation of extremely short pulses. At the same time, we also obtained other types of exact solutions.

  17. Probing the dispersion properties of 1D nanophotonic waveguides with far-field Fourier optics

    DEFF Research Database (Denmark)

    Le Thomas, N.; Jágerská, J.; Houdré, R.

    2008-01-01

    We present an advanced Fourier space imaging technique to probe guided light in nanophotonic structures with an effective numerical aperture of 2.5. This superresolution technique allows us to successfully investigate the dispersive properties of 1D nanowaveguides such as photonic crystal W1...

  18. All optical up-converted signal generation with high dispersion tolerance using frequency quadrupling technique for radio over fiber system

    Science.gov (United States)

    Gu, Yiying; Zhao, Jiayi; Hu, Jingjing; Kang, Zijian; Zhu, Wenwu; Fan, Feng; Han, Xiuyou; Zhao, Mingshan

    2016-05-01

    A novel all optical up-converted signal generation scheme with optical single-sideband (OSSB) technique for radio over fiber (RoF) application is presented and experimentally demonstrated using low-bandwidth devices. The OSSB signal is generated by one low-bandwidth intensity LiNbO3 Mach-Zehnder modulator (LN-MZM) under frequency quadrupling modulation scheme and one low-bandwidth LN-MZM under double sideband carrier suppressed modulation (DSB-CS) scheme. The proposed all OSSB generation scheme is capable of high tolerance of fiber chromatic dispersion induced power fading (DIPF) effect. Benefiting from this novel OSSB generation scheme, a 26 GHz radio frequency (RF) signal up-conversion is realized successfully when one sideband of the optical LO signal is reused as the optical carrier for intermediate frequency (IF) signal modulation. The received vector signal transmission over long distance single-mode fiber (SMF) shows negligible DIPF effect with the error vector magnitude (EVM) of 15.7% rms. In addition, a spurious free dynamic range (SFDR) of the OSSB up-converting system is measured up to 81 dB Hz2/3. The experiment results indicate that the proposed system may find potential applications in future wireless communication networks, especially in microcellular personal communication system (MPCS).

  19. Optical characterization of HfO{sub 2} by spectroscopic ellipsometry: Dispersion models and direct data inversion

    Energy Technology Data Exchange (ETDEWEB)

    Sancho-Parramon, Jordi [Ruder Boskovic Institute, Bijenicka 54, Zagreb 10000 (Croatia)], E-mail: j.sancho.parramon@gmail.com; Modreanu, Mircea [University College Cork, Tyndall National Institute (TYNDALL), Lee Maltings, Prospect Row, Cork (Ireland); Bosch, Salvador [Universitat de Barcelona, Marti i Franques 1, Barcelona 08930 (Spain); Stchakovsky, Michel [HORIBA Jobin Yvon, Thin Film Division, Chilly-Mazarin 91380 (France)

    2008-09-30

    Hafnium oxide (HfO{sub 2}) has attracted much interest as high-k material of choice for gate oxide replacement in future CMOS technologies and for its use in optical coating technology. The determination of optical properties, like refractive index and bandgap, is focus of intense research, since the optical constants of HfO{sub 2} depend on the physical microstructure and the deposition methods and conditions. In the present study optical characterization of very thin HfO{sub 2} films deposited by plasma ion assisted deposition and annealed at different temperatures is carried out. The characterization is performed using ellipsometric measurements in the spectral range from 1.5 to 8 eV and by using the Tauc-Lorentz and Cody-Lorentz dispersion models. In addition, direct inversion of the ellipsometric data is also carried out. The combination of the Cody-Lorentz model with Urbach tail results in the best description of the data and enables to determine meaningful parameters. On the other hand, the direct data inversion is shown to be useful to provide additional information like the presence of subgap absorption peaks and points out features associated to the crystallinity of the material.

  20. Dispersive optical-model potential for protons in 100 ⩽ A ⩽ 132 even–even tin isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bespalova, O. V., E-mail: besp@sinp.msu.ru; Romanovsky, E. A.; Spasskaya, T. I.; Klimochkina, A. A. [Moscow State University (Russian Federation)

    2015-10-15

    Data on single-particle energies, differential elastic-scattering cross sections, and total cross sections for proton-induced reactions on stable tin isotopes were analyzed on the basis of the dispersive optical model. Good agreement with experimental data was obtained by setting the parameters of the dispersive optical potential to values averaged over the tin isotopic chain and by assuming that the dependence of surface absorption on the neutron–proton asymmetry is close to a traditional dependence. Predictive calculations for single-particle proton spectra and total reaction cross sections were performed for the doubly magic isotopes {sup 100,132}Sn. The calculated values of the energy gap between the 1h{sub 11/2}–1g{sub 7/2} and 1g{sub 7/2}–2d{sub 5/2} states were found to be in good agreement with the results of calculations performed with allowance for the tensor component of the effective nucleon–nucleon interaction.

  1. Non-Linear Noise Contributions in Highly Dispersive Optical Transmission Systems

    Science.gov (United States)

    Matera, Francesco

    2016-01-01

    This article reports an analytical investigation, confirmed by numerical simulations, about the non-linear noise contribution in single-channel systems adopting generic modulation-detection formats in long links with both managed and unmanaged dispersion compensation and its impact in system performance. This noise contribution is expressed in terms of a pulse non-linear interaction length and permits a simple calculation of the Q-factor. Results point out the dependence of this non-linear noise on the number of amplifiers spans, N, according to the adopted chromatic dispersion compensation scheme, the modulation-detection format, and the signal baud rate. It is also shown how the effects of polarization multiplexing can be taken into account and how this single-channel non-linear noise contribution can be used in a wavelength-division multiplexing (WDM) environment.

  2. Nonlinear optical properties of polymer dispersed liquid crystals doped with La2CaB10019

    Science.gov (United States)

    Zegadlo, Krzysztof B.; El Ouazzani, Hasnaa; Cieslik, Iwona; Weglowski, Rafal; Zmija, Jozef; Klosowicz, Stanislaw; Majchrowski, Andrzej; Mysliwiec, Jaroslaw; Sahraoui, Bouchta; Karpierz, Miroslaw A.

    2012-08-01

    Second order nonlinearity in polymer dispersed liquid crystal structures containing La2CaB10O19 nanocrystals were measured with use of the Maker fringes method. The composites with different concentration of La2CaB10O19 crystallites or without them were compared. It was shown that there is a strong influence of the crystals concentration on the second harmonic generation in such structures which can be additionally modified by external electric field.

  3. Treatment of atlantoaxial rotatory fixation with botulinum toxin muscle block and manipulation.

    Science.gov (United States)

    Lin, Chia-Hung; Chen, Chun-Jung; Chen, Chuan-Mu; Liao, Su-Lan; Raung, Shue-Ling; Tsai, Sen-Wei

    2010-04-01

    Slippage after reduction of atlantoaxial rotatory fixation (AARF) is usually treated with repeated cervical traction and brace immobilization. To date, no data have been published on the management of muscle spasm during treatment. Here, we describe the case of a 7-year-old girl with AARF for 1 month who visited our hospital for treatment. During physical examination, spasm of the sternocleidomastoid muscle was noted. The patient was treated with manipulative reduction, and slippage after reduction was managed with botulinum spasticity block of the sternocleidomastoid and splenius capitis muscles, and repeated manipulation. Cervical orthosis immobilization with a rehabilitation program of isometric contract-relax exercise for the neck was conducted for 3 months. The subject had full recovery from AARF at 1-year follow-up. This report demonstrates that, in selected cases of slippage after reduction from AARF, conservative management with manipulation under anesthesia is a good method, and the muscle components may play a crucial role in AARF.

  4. Arthroscopic and open management of posterolateral rotatory instability of the elbow.

    Science.gov (United States)

    O'Brien, Michael J; Savoie, Felix H

    2014-09-01

    Posterolateral rotatory instability (PLRI) is the most common cause of residual instability following a simple elbow dislocation. PLRI may result from trauma or iatrogenic injury to the radial ulnohumeral ligament during treatment for other conditions, such as lateral epicondylitis. PLRI can be identified through a combination of history and physical examination, and confirmed with magnetic resonance imaging arthrography. Once diagnosed, surgery is necessary to correct persistent instability. Instability can be confirmed arthroscopically through several findings, including subluxation of the radial head on the capitellum and the arthroscopic "drive through sign of the elbow." Acute repairs, both open and arthroscopic, heal with excellent patient outcomes. In the chronic setting, graft reconstruction may be required. This report describes arthroscopic repair of the radial ulnohumeral ligament and open reconstruction with associated outcomes. A high index of suspicion is necessary to correctly diagnosis this condition in patients with lateral elbow pain and feelings of instability.

  5. On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range

    CERN Document Server

    Lin, Guoping

    2015-01-01

    Optical whispering gallery mode (WGM) resonators have been very attracting platforms for versatile Kerr frequency comb generations. We report a systematic study on the material dispersion of various optical materials that are capable of supporting quality factors above $10^9$. Using an analytical approximation of WGM resonant frequencies in disk resonators, we investigate the effect of the geometry and transverse mode order on the total group-velocity dispersion ($GVD$). We demonstrate that the major radii and the radial mode indices play an important role in tailoring the $GVD$ of WGM resonators. In particular, our study shows that in WGM disk-resonators, the polar families of modes have very similar $GVD$, while the radial families of modes feature dispersion values that can differ by up to several orders of magnitude. The effect of these giant dispersion shifts are experimentally evidenced in Kerr comb generation with magnesium fluoride. From a more general perspective, this critical feature enables to pus...

  6. ASSESSMENT OF EFFECTIVENESS OF TB POSTING DURING THE COMPULSORY ROTATORY RESIDENTIAL INTERNSHIP (CRRI PROGRAMME

    Directory of Open Access Journals (Sweden)

    Pradeep Aggarwal

    2011-12-01

    Full Text Available Research Question: What is the effectiveness of TB posting during the Compulsory Rotatory Residential Internship (CRRI programme? Objectives: To assess the effectiveness of TB posting during the CRRI programme. To find out the need of making Tuberculosis & Respiratory Diseases Department posting mandatory during CRRI Programme. Study Design: Cross Sectional study. Study Duration: 12 months i.e. 01st April 2009 till 31st March 2010 Participants: 90 students who joined the CRRI programme formed the study group. Out of these 90 interns only 57 (64% of them joined their two months Compulsory Rotatory Internship in the Department of Community Medicine and these were posted in Tuberculosis & Respiratory Diseases Department for 15 days. Methodology: A pre-designed pre-tested self-administered questionnaire was administered to the participants on the first day and last day of their posting in Tuberculosis & Respiratory Diseases Department. The results were analysed by using suitable statistical package. Results: The mean pre-test score was 28 (49.6% and the mean post-test score was 38 (61.5%. It was observed that there was a 27% improvement in the knowledge of the participants when the question about the year of launching of RNTCP programme in India was asked. A remarkable improvement (46% was found in the difference between pre and post-test knowledge of the participants when the questions like “Who are the DOTS providers” and “What is the colour coding of boxes for different categories of patients” were asked. A significant difference in the knowledge was found in the pre and post-test assessment in reference to Tuberculosis and its National Programm

  7. Dispersion spreading of biphotons in optical fibres and two-photon interference

    CERN Document Server

    Brida, G; Genovèse, M; Gramegna, M; Krivitsky, L A

    2006-01-01

    We present the first observation of two-photon polarization interference structure in the second-order Glauber's correlation function of two-photon light generated via type-II spontaneous parametric down-conversion. In order to obtain this result, two-photon light is transmitted through an optical fibre and the coincidence distribution is analyzed by means of the START-STOP method. Beyond the experimental demonstration of an interesting effect in quantum optics, these results also have considerable relevance for quantum communications.

  8. Dispersion spreading of biphotons in optical fibers and two-photon interference.

    Science.gov (United States)

    Brida, G; Chekhova, M V; Genovese, M; Gramegna, M; Krivitsky, L A

    2006-04-14

    We present the first observation of two-photon polarization interference structure in the second-order Glauber correlation function of two-photon light generated via type-II spontaneous parametric down-conversion. In order to obtain this result, two-photon light is transmitted through an optical fiber and the coincidence distribution is analyzed by means of the start-stop method. Beyond the experimental demonstration of an interesting effect in quantum optics, these results also have considerable relevance for quantum communications.

  9. Effects of multi-context information recorded at different regions in holographic polymer-dispersed liquid crystal on optical reconfiguration

    Science.gov (United States)

    Ogiwara, Akifumi; Watanabe, Minoru

    2016-08-01

    A holographic polymer-dispersed liquid crystal (HPDLC) memory to record multi-context information for an optically reconfigurable gate array is formed by constructing a laser illumination system to implement successive laser exposures at different small regions in a glass cell filled with LC composites. The context pattern arrangements for circuit information are designed in a 3 × 3 in.2 photomask by electron beam lithography, and they are recorded as laser interference patterns at nine regions separated in an HPDLC sample by a laser interferometer composed of movable pinhole and photomask plates placed on motorized stages. The multi-context information reconstructed from the different regions in the HPDLC is written to a photodiode array in a gate-array VLSI by switching only the position of laser irradiation using the displacement of the pinhole plate under the control of a personal computer (PC). The effects of multi-context information recorded at different regions in the HPDLC on optical reconfiguration are discussed in terms of the optical system composed of ORGA VLSI and HPDLC memory. The internal structures in the HPDLC memory formed by multi-context recording are investigated by scanning electron microscopy (SEM) observation, and the configurations composed of LC and polymer phases are revealed at various regions in the HPDLC memory.

  10. Laser stabilization to an atomic transition using an optically generated dispersive lineshape

    CERN Document Server

    Queiroga, Fabiano; Mestre, Valdeci; Vidal, Itamar; de Silans, Thierry Passerat; Oriá, Marcos; Chevrollier, Martine

    2012-01-01

    We report on a simple and robust technique to generate a dispersive signal which serves as an error signal to electronically stabilize a monomode cw laser emitting around an atomic resonance. We explore nonlinear effects in the laser beam propagation through a resonant vapor by way of spatial filtering. The performance of this technique is validated by locking semiconductor lasers to the cesium and rubidiumD2 line and observing long-term reduction of the emission frequency drifts, making the laser well adapted for many atomic physics applications.

  11. Bloch Wave Approach to the Optics of Crystals: The Role of Spatial Dispersion

    Science.gov (United States)

    2000-09-29

    of Crystals: The Role of Spatial Dispersion S. Ponti, C. Oldano, and M. Becchi Dipartimento di Fisica del Politecnico di Torino Corso Duca degli...explicitly depends on the wave vector k of the internal plane wave, i.e. F = F(k). The 408 tensor field e(r) is well known for many periodic liquid...structure: eG-eG_+(3) where = (y + q-)21 _ (k + qj(k + q -) (4) 1 is the 3 x 3 identity matrix, (k + q-) (k + q- is a dyadic product, and the vectors

  12. Observation of Motion Dependent Nonlinear Dispersion with Narrow Linewidth Atoms in an Optical Cavity

    CERN Document Server

    Westergaard, Philip G; Tieri, David; Matin, Rastin; Cooper, John; Holland, Murray; Ye, Jun; Thomsen, Jan W

    2014-01-01

    As an alternative to state-of-the-art laser frequency stabilisation using ultra-stable cavities, it has been proposed to exploit the non-linear effects from coupling of atoms with a narrow atomic transition to an optical cavity. Here we have constructed such a system and observed non-linear phase shifts of a narrow optical line by strong coupling of a sample of strontium-88 atoms to an optical cavity. The sample temperature of a few mK provides a domain where the Doppler energy scale is several orders of magnitude larger than the narrow linewidth of the optical transition. This makes the system sensitive to velocity dependent multi-photon scattering events (Dopplerons) that affect the cavity transmission significantly while leaving the phase signature relatively unaffected. By varying the number of atoms and the intra-cavity power we systematically study this non-linear phase signature which displays roughly the same features as for much lower temperature samples. This demonstration in a relatively simple sys...

  13. Optical Cherenkov radiation in an As2S3 slot waveguide with four zero-dispersion wavelengths

    DEFF Research Database (Denmark)

    Wang, Shaofei; Hu, Jungao; Guo, Hairun

    2013-01-01

    We propose an approach for an efficient generation of optical Cherenkov radiation (OCR) in the near-infrared by tailoring the waveguide dispersion for a zero group-velocity mismatching between the radiation and the pump soliton. Based on an As2S3 slot waveguide with subwavelength dimensions......, dispersion profiles with four zero dispersion wavelengths are found to produce a phase-matching nonlinear process leading to a broadband resonant radiation. The broadband OCR investigated in the chalcogenide waveguide may find applications in on-chip wavelength conversion and near-infrared pulse generation....

  14. Optical activity of chirally distorted nanocrystals

    Science.gov (United States)

    Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-05-01

    We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

  15. Optical and Structural Investigation of CdSe Quantum Dots Dispersed in PVA Matrix and Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Pallabi Phukan

    2013-01-01

    Full Text Available CdSe quantum dots (QDs dispersed in polyvinyl alcohol (PVA matrix with their sizes within the quantum dot regime have been synthesized via a simple heat induced thermolysis technique. The effect of the concentrations of the cadmium source on the optical properties of CdSe/PVA thin films was investigated through UV-Vis absorption spectroscopy. The structural analysis and particle size determination as well as morphological studies of the CdSe/PVA nanocomposite thin films were done with the help of X-ray diffraction (XRD and transmission electron microscopy (TEM. The XRD analysis reveals that CdSe/PVA nanocomposite thin film has a hexagonal (wurtzite structure. A prototype thin film solar cell of CdSe/CdTe has been synthesized and its photovoltaic parameters were measured.

  16. Computed tomography and optical remote sensing: Development for the study of indoor air pollutant transport and dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, Anushka Christina [Univ. of California, Berkeley, CA (United States)

    1995-06-01

    This thesis investigates the mixing and dispersion of indoor air pollutants under a variety of conditions using standard experimental methods. It also extensively tests and improves a novel technique for measuring contaminant concentrations that has the potential for more rapid, non-intrusive measurements with higher spatial resolution than previously possible. Experiments conducted in a sealed room support the hypothesis that the mixing time of an instantaneously released tracer gas is inversely proportional to the cube root of the mechanical power transferred to the room air. One table-top and several room-scale experiments are performed to test the concept of employing optical remote sensing (ORS) and computed tomography (CT) to measure steady-state gas concentrations in a horizontal plane. Various remote sensing instruments, scanning geometries and reconstruction algorithms are employed. Reconstructed concentration distributions based on existing iterative CT techniques contain a high degree of unrealistic spatial variability and do not agree well with simultaneously gathered point-sample data.

  17. Implications for (d ,p ) reaction theory from nonlocal dispersive optical model analysis of 40Ca(d ,p )41Ca

    Science.gov (United States)

    Waldecker, S. J.; Timofeyuk, N. K.

    2016-09-01

    The nonlocal dispersive optical model (NLDOM) nucleon potentials are used for the first time in the adiabatic analysis of a (d ,p ) reaction to generate distorted waves both in the entrance and exit channels. These potentials were designed and fitted by Mahzoon et al. [Phys. Rev. Lett. 112, 162503 (2014), 10.1103/PhysRevLett.112.162503] to constrain relevant single-particle physics in a consistent way by imposing the fundamental properties, such as nonlocality, energy-dependence and dispersive relations, that follow from the complex nature of nuclei. However, the NLDOM prediction for the 40Ca(d ,p )41Ca cross sections at low energy, typical for some modern radioactive beam ISOL (isotope separation online) facilities, is about 70% higher than the experimental data despite being reduced by the NLDOM spectroscopic factor of 0.73. This overestimation comes most likely either from insufficient absorption or due to constructive interference between ingoing and outgoing waves. This indicates strongly that additional physics arising from many-body effects is missing in the widely used current versions of (d ,p ) reaction theories.

  18. Diagnostics of two-phase flows with high concentration of a solid dispersed phase using fiber-optic sensors

    Science.gov (United States)

    Evseev, A. R.

    2016-10-01

    This paper is focused on the physical modeling of two-phase flows with high concentration of the dispersed phase. The fiber-optical sensors and their calibration procedure were developed for bubble concentration measurements in the fluidized bed apparatus (FB). Distributions of bubble concentration in the 2D and 3D FB apparatuses, which determine the quality of fluidization and local density of filling material, were obtained. The techniques of particle velocity and concentration measurements in the circulating fluidized bed (CFB) was developed using three-fiber sensor (the differential scheme of LDA) operated in backscattering regime. Sensor operation was analyzed and the main systematic measurement errors were determined; the original construction of the sensor was designed. The data on the velocity and concentration profiles of dispersed phase in a large-scale CFB apparatus were obtained for fluidization of particles by air. It was found that with increasing circulation velocity in the CFB apparatus, the particle concentration increases in the near-wall region much higher than in the flow core. The method of particle velocity measurements in a liquid was developed using the laser Doppler fiber anemometer (LDFA-1), operating in the backscattering regime. The signal to noise ratio was obtained for particles of different size and material in test measurements. The rates of consolidated precipitation of cryolite particles in a sedimentation apparatus with the inclined walls were measured.

  19. First Stellar Velocity Dispersion Measurement of a Luminous Quasar Host with Gemini North Laser Guide Star Adaptive Optics

    CERN Document Server

    Watson, Linda C; Dasyra, Kalliopi M; Bentz, Misty C; Ferrarese, Laura; Peterson, Bradley M; Pogge, Richard W; Tacconi, Linda J

    2008-01-01

    We present the first use of the Gemini North laser guide star adaptive optics (LGS AO) system and an integral field unit (IFU) to measure the stellar velocity dispersion of the host of a luminous quasar. The quasar PG1426+015 (z=0.086) was observed with the Near-Infrared Integral Field Spectrometer (NIFS) on the 8m Gemini North telescope in the H-band as part of the Science Verification phase of the new ALTAIR LGS AO system. The NIFS IFU and LGS AO are well suited for host studies of luminous quasars because one can achieve a large ratio of host to quasar light. We have measured the stellar velocity dispersion of PG1426+015 from 0.1'' to 1'' (0.16 kpc to 1.6 kpc) to be 217+/-15 km/s based on high signal-to-noise ratio measurements of Si I, Mg I, and several CO bandheads. This new measurement is a factor of four more precise than a previous measurement obtained with long-slit spectroscopy and good, natural seeing, yet was obtained with a shorter net integration time. We find that PG1426+015 has a velocity disp...

  20. Universal dispersion model for characterization of optical thin films over a wide spectral range: application to hafnia.

    Science.gov (United States)

    Franta, Daniel; Nečas, David; Ohlídal, Ivan

    2015-11-01

    A dispersion model capable of expressing the dielectric response of a broad class of optical materials in a wide spectral range from far IR to vacuum UV is described in detail. The application of this universal dispersion model to a specific material is demonstrated using the ellipsometric and spectrophotometric characterization of a hafnia film prepared by vacuum evaporation on silicon substrate. The characterization utilizes simultaneous processing of data from multiple techniques and instruments covering the wide spectral range and includes the characterization of roughness, nonuniformity, transition layer, and native oxide layer on the back of the substrate. It is shown how the combination of measurements in light reflected from both sides of the sample and transmitted light allows the separation of weak absorption in films and substrates. This approach is particularly useful in the IR region where the absorption structures in films and substrates often overlap and a prior measurement of the bare substrate may be otherwise necessary for precise separation. Individual phenomena that contribute to the dielectric response, i.e., interband electronic transitions, electronic excitations involving the localized states, and phonon absorption, are discussed in detail. A quantitative analysis of absorption on localized states, permitting the separation of transitions between localized states from transitions between localized and extended states, is utilized to obtain estimates of the density of localized states and film stoichiometry.

  1. Digital compensation of cross-phase modulation distortions using perturbation technique for dispersion-managed fiber-optic systems.

    Science.gov (United States)

    Liang, Xiaojun; Kumar, Shiva; Shao, Jing; Malekiha, Mahdi; Plant, David V

    2014-08-25

    A digital compensation scheme based on a perturbation theory for mitigation of cross-phase modulation (XPM) distortions is developed for dispersion-managed fiber-optic communication systems. It is a receiver-side scheme that uses a hard-decision unit to estimate data for the calculation of XPM fields using the perturbation technique. The intra-channel nonlinear distortions are removed by intra-channel digital backward propagation (DBP) based on split-step Fourier scheme before the hard-decision unit. The perturbation technique is shown to be effective in mitigating XPM distortions. However, wrong estimations in the hard-decision unit result in performance degradation. A hard-decision correction method is proposed to correct the wrong estimations. Numerical simulations show that the hybrid compensation scheme with DBP for dispersion and intra-channel nonlinear impairments compensation and the perturbation technique for XPM compensation brings up to 3.7 dBQ and 1.7 dBQ improvements as compared with the schemes of linear compensation only and intra-channel DBP, respectively. The perturbation technique for XPM compensation requires only one-stage (or two-stage when hard-decision correction is applied) compensation and symbol-rate signal processing.

  2. Dispersive response of atoms trapped near the surface of an optical nanofiber with applications to QND measurement and spin squeezing

    CERN Document Server

    Qi, Xiaodong; Jessen, Poul S; Deutsch, Ivan H

    2015-01-01

    We study the strong coupling between photons and atoms that can be achieved in an optical nanofiber geometry when the interaction is dispersive. While the Purcell enhancement factor for spontaneous emission into the guided mode does not reach the strong-coupling regime for individual atoms, one can obtain high cooperativity for ensembles of a few thousand atoms due to the tight confinement of the guided modes and constructive interference over the entire chain of trapped atoms. We calculate the dyadic Green's function, which determines the scattering of light by atoms in the presence of the fiber, and thus the phase shift and polarization rotation induced on the guided light by the trapped atoms. The Green's function is related to a full Heisenberg-Langevin treatment of the dispersive response of the quantized field to tensor polarizable atoms. We apply our formalism to quantum nondemolition (QND) measurement of the atoms via polarimetry. We study shot-noise-limited detection of atom number for atoms in a com...

  3. Optical Properties of Nanocellulose Dispersions in Water, Dimethylformamide and Poly(Methyl Methacrylate)

    Science.gov (United States)

    2013-10-01

    constitute an official endorsement or approval of the use thereof. Destroy this report when it is no longer needed. Do not return it to the originator...broad array of Army platforms. A common approach is to use optically transparent fiber or particulate additives for reinforcement. However, there are...Cellulose is a carbohydrate building block obtained from many prevalent resources to include wood, hemp , ramie, cotton, and bacteria (Moon et al

  4. Temperature Sensitivity of an Atomic Vapor Cell-Based Dispersion-Enhanced Optical Cavity

    Science.gov (United States)

    Myneni, K.; Smith, D. D.; Chang, H.; Luckay, H. A.

    2015-01-01

    Enhancement of the response of an optical cavity to a change in optical path length, through the use of an intracavity fast-light medium, has previously been demonstrated experimentally and described theoretically for an atomic vapor cell as the intracavity resonant absorber. This phenomenon may be used to enhance both the scale factor and sensitivity of an optical cavity mode to the change in path length, e.g. in gyroscopic applications. We study the temperature sensitivity of the on-resonant scale factor enhancement, S(sub o), due to the thermal sensitivity of the lower-level atom density in an atomic vapor cell, specifically for the case of the Rb-87 D(sub 2) transition. A semi-empirical model of the temperature-dependence of the absorption profile, characterized by two parameters, a(sub o)(T) and gamma(sub a)(T) allows the temperature-dependence of the cavity response, S(sub o)(T) and dS(sub o)/dT to be predicted over a range of temperature. We compare the predictions to experiment. Our model will be useful in determining the useful range for S(sub o), given the practical constraints on temperature stability for an atomic vapor cell.

  5. Dispersion characteristics of optically excited coplanar striplines - Comprehensive full-wave analysis

    Science.gov (United States)

    Phatak, Dhananjay S.; Defonzo, A. P.; Das, Nirod K.

    1990-11-01

    A comprehensive full-wave formulation is developed to evaluate the dispersion and losses for coplanar striplines on substrates of finite and infinite thicknesses is presented. The loss mechanisms incorporated in the analysis are substrate losses and dielectric material losses. The method of Das and Pozar (1987) is generalized to include a complex propagation vector and can be used over a wide frequency range. A large range of line dimensions can also be handled, limits being set by the accuracy of the moment method. Metal losses can also be incorporated into this analysis by applying the appropriate boundary conditions for lossy metal. Analytically, the excitation of substrate modes is shown to correspond to the occurrence of the poles of the Green function in the reaction integrals. Results of the full-wave analysis are in good agreement with those obtained by established theory.

  6. Aloha - Optics studies by combined kick-response and dispersion fits.

    CERN Document Server

    Fuchsberger, K

    2009-01-01

    The Aloha software is based on a JAVA reimplementation of the former LOCO response fitting code [1]. The project was initiated in order to have a tool that is available online in the control room to quickly analyze kick response data during the LHC injection tests and startup. Later it was extended to handle dispersion data as another source for fit-constraints and to import other input data as for example alignment and trim-values. It was already successfully used to determine monitor- an corrector-gains as well as identifying various error sources during the LHC injection tests. This note describes the principles used by Aloha as well as some implementation details of this software package.

  7. Novel Synchronous Linear and Rotatory Micro Motors Based on Polymer Magnets with Organic and Inorganic Insulation Layers

    Directory of Open Access Journals (Sweden)

    Andreas WALDSCHIK

    2008-12-01

    Full Text Available In this work, we report on the development of several synchronous motors with rotatory or linear movements. The synchronous micro motors are brushless DC motors or stepper motors with electrically controlled commutation consisting of a stator and a rotor. The rotor is mounted onto the stator and is adjusted by an integrated guidance. Inside the stator different coil systems are realized, like double layer sector coils or special nested coils. The coil systems can be controlled by three or six phases depending on the operational mode. Furthermore, inorganic insulation layers were used in order to reduce the thickness of the system. By this means four layers of electrical conductors can be realized especially for the 2D devices. The smallest diameter of the rotatory motor is 1 mm and could be successfully driven.

  8. Transverse vibration of Bernoulli Euler beams carrying point masses and taking into account their rotatory inertia: Exact solution

    Science.gov (United States)

    Maiz, Santiago; Bambill, Diana V.; Rossit, Carlos A.; Laura, P. A. A.

    2007-06-01

    The situation of structural elements supporting motors or engines attached to them is usual in technological applications. The operation of the machine may introduce severe dynamic stresses on the beam. It is important, then, to know the natural frequencies of the coupled beam-mass system, in order to obtain a proper design of the structural elements. An exact solution for the title problem is obtained in closed-form fashion, considering general boundary conditions by means of translational and rotatory springs at both ends. The model allows to analyze the influence of the masses and their rotatory inertia on the dynamic behavior of beams with all the classic boundary conditions, and also, as particular cases, to determine the frequencies of continuous beams.

  9. TiO₂ nanowire dispersions in viscous polymer matrix: electrophoretic alignment and optical properties.

    Science.gov (United States)

    Šutka, Andris; Saal, Kristjan; Kisand, Vambola; Lõhmus, Rünno; Joost, Urmas; Timusk, Martin

    2014-10-17

    The changes in optical properties during TiO₂ nanowire orientation in polydimethylsiloxane (PDMS) matrix under the influence of an electric field are strongly influenced by nanowire (NW) diameter. It was demonstrated for the first time that either positive or negative change in transmittance can be induced by NW alignment parallel to the electric field depending on the NW diameter. These effects can be explained by the interplay between scattering and reflectance. Experimental findings reported could be important for smart window applications for the regulation of visible or even infrared transparency, thus reducing the energy consumption by air conditioning systems in buildings and automobiles in the future.

  10. Preparation and third-order nonlinear optical property of poly(urethane-imide containing dispersed red chromophore

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available A novel poly(urethane-imide (PUI containing dispersed red chromophore was synthesized. The PUI was characterized by FT-IR, UV-Vis, DSC and TGA. The results of DSC and TGA indicated that the PUI exhibited high thermal stability up to its glass-transition temperature (Tg of 196°C and 5% heat weight loss temperature of 229°C. According to UV-Vis spectrum and working curve, the maximum molar absorption coefficient and absorption wavelength were measured. They were used to calculate the third-order nonlinear optical coefficient χ(3. At the same time, the chromophore density of PUI, nonlinear refractive index coefficient and molecular hyperpolarizability of PUI were obtained. The fluorescence spectra of PUI and model compound DR-19 were determined at excitation wavelength 300 nm. The electron donor and acceptor in polymer formed the exciplex through the transfer of the electric charges. The results show that the poly(urethane-imide is a promising candidate for application in optical devices.

  11. Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films

    Directory of Open Access Journals (Sweden)

    Yujian Sun

    2016-12-01

    Full Text Available Polymer-dispersed liquid crystal (PDLC films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

  12. Determination and analysis of dispersive optical constant of TiO{sub 2} and Ti{sub 2}O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Aziz, M.M. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)]. E-mail: melaziz@link.net; Yahia, I.S. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Wahab, L.A. [Physics Department, National Center for Radiation Research and Technology, Naser City, Cairo (Egypt); Fadel, M. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Afifi, M.A. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)

    2006-09-30

    Electron beam evaporation technique was used to prepare TiO{sub 2} and Ti{sub 2}O{sub 3} thin films onto glass substrates of thicknesses 50, 500 and 1000nm for each sample. The structural investigations revealed that the as-deposited films are amorphous in nature. Transmittance measurements in the wavelength range (350-2000nm) were used to calculate the refractive index n and the absorption index k using Swanepoel's method. The optical constants such as optical band gap E{sub g}{sup opt}, optical conductivity {sigma}{sub opt}, complex dielectric constant, relaxation time {tau} and dissipation factor tan{delta} were determined. The analysis of the optical absorption data revealed that the optical band gap E{sub g} was indirect transitions. The optical dispersion parameters E{sub o} and E{sub d} were determined according to Wemple and Didomenico method.

  13. Simultaneous all-optical demultiplexing and regeneration based on self-phase and cross-phase modulation in a dispersion shifted fiber

    DEFF Research Database (Denmark)

    Yu, Jianjun; Jeppesen, Palle

    2001-01-01

    Simultaneous demultiplexing and regeneration of 40-Gb/s optical time division multiplexed (OTDM) signal based on self-phase and cross-phase modulation in a dispersion shifted fiber is numerically and experimentally investigated. The optimal walkoff time between the control pulse and OTDM signal...

  14. Measurement of grain size of polycrystalline materials with confocal energy dispersive micro-X-ray diffraction technology based on polycapillary X-ray optics

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Weiyuan; Liu, Zhiguo [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi, E-mail: stx@bnu.edu.cn [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Peng, Song [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma, Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Li, Fangzuo; Sun, Xuepeng; Ding, Xunliang [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-11-11

    The confocal energy dispersive micro-X-ray diffraction (EDMXRD) based on polycapillary X-ray optics was used to determine the grain size of polycrystalline materials. The grain size of a metallographic specimen of nickel base alloy was measured by using the confocal EDMXRD. The experimental results demonstrated that the confocal EDMXRD had potential applications in measuring large grain size.

  15. Optical Solitary Waves in Fourth-Order Dispersive Nonlinear Schr(o)dinger Equation with Self-steepening and Self-frequency Shift

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By making use of the generalized sine-Gordon equation expansion method, we find cnoidal periodic wave solutions and fundamental bright and dark optical solitarywave solutions for the fourth-order dispersive and the quintic nonlinear Schrodinger equation with self-steepening, and self-frequency shift. Moreover, we discuss the formation conditions of the bright and dark solitary waves.

  16. Modal dispersion, pulse broadening and maximum transmission rate in GRIN optical fibers encompass a central dip in the core index profile

    Science.gov (United States)

    El-Diasty, Fouad; El-Hennawi, H. A.; El-Ghandoor, H.; Soliman, Mona A.

    2013-12-01

    Intermodal and intramodal dispersions signify one of the problems in graded-index multi-mode optical fibers (GRIN) used for LAN communication systems and for sensing applications. A central index dip (depression) in the profile of core refractive-index may occur due to the CVD fabrication processes. The index dip may also be intentionally designed to broaden the fundamental mode field profile toward a plateau-like distribution, which have advantages for fiber-source connections, fiber amplifiers and self-imaging applications. Effect of core central index dip on the propagation parameters of GRIN fiber, such as intermodal dispersion, intramodal dispersion and root-mean-square broadening, is investigated. The conventional methods usually study optical signal propagation in optical fiber in terms of mode characteristics and the number of modes, but in this work multiple-beam Fizeau interferometry is proposed as an inductive but alternative methodology to afford a radial approach to determine dispersion, pulse broadening and maximum transmission rate in GRIN optical fiber having a central index dip.

  17. The determination of the thickness and the optical dispersion property of gold film using spectroscopy of a surface plasmon in the frequency domain

    Institute of Scientific and Technical Information of China (English)

    Huang Yan; Ye Hong-An; Li Song-Quan; Dou Yin-Feng

    2013-01-01

    We propose to use wavelength modulation approach,i.e.,the spectroscopy of a surface plasmon in the frequency domain,to characterize the optical dispersion property of gold film.Using this method,we determine the dispersion relationship of gold film in a wavelength range from 537.12 nm to 905.52 nm,and our results accord well with the reported results by other authors.This method is particularly suited for studying the optical dispersion properties of thin metal films,because a series of dielectric constants over a wide spectral range can be determined simultaneously via only a single scan of the incident angle,thereby avoiding the repeated measurements required when using the angular modulation approach.

  18. Theoretical analysis and experimental verification of a cost-effective chromatic dispersion monitoring method in a 40-Gb/s optical fiber communication system

    Institute of Scientific and Technical Information of China (English)

    Yan Li; Jin Zhang; Jinlong Yu; Wencai Jing; Yimo Zhang; Ge Zhou

    2005-01-01

    A cost-effective technique for in-service chromatic dispersion monitoring in a 40-Gb/s optical communication system is proposed. Microwave devices are adopted to detect the electrical power of a specific frequency band. A simplified theoretical model is proposed and discussed focusing on the relationship between electrical power and chromatic dispersion at different frequency bands. The dynamic monitoring of chromatic dispersion is achieved using devices such as PIN detector, microwave amplifier, narrow-band microwave filter, and electrical power detector. The maximum detectable chromatic dispersion is 130 ps/nm and a resolution of 5.2 ps/nm/dB has been achieved in the frequency band centered at 12 GHz.

  19. Sellmeier and thermo-optic dispersion formulas for CdGa2S4 and their application to the nonlinear optics of Hg1-xCdxGa2S4

    Science.gov (United States)

    Kato, Kiyoshi; Umemura, Nobuhiro; Petrov, Valentin

    2017-03-01

    This paper reports the Sellmeier and thermo-optic dispersion formulas for CdGa2S4 that provide excellent reproduction of the temperature-dependent phase-matching conditions in Hg0.35Cd0.65Ga2S4 and Hg0.51Cd0.49Ga2S4 for second-harmonic generation (SHG) and sum-frequency generation (SFG) in the 0.897-10.5910 μm spectral range coupled with Sellmeier and thermo-optic dispersion formulas for HgGa2S4 presented in our previous papers (Kato et al., 2016 [1]; Umemura et al., 2012 [2]).

  20. Quantification of C2 cervical spine rotatory fixation by X-ray, MRI and CT

    Energy Technology Data Exchange (ETDEWEB)

    Gradl, Georg [Chirurgische Klinik und Poliklinik der Universitaet Rostock, Abteilung Unfall- und Wiederherstellungschirurgie, Rostock (Germany); Maier-Bosse, Tamara; Staebler, Axel [Institut fuer Radiologische Diagnostik der Universitaet Muenchen, Klinikum Grobetahadern, Munich (Germany); Penning, Randolph [Institut fuer Rechtsmedizin der Universitaet Muenchen, Munich (Germany)

    2005-02-01

    Atlanto-axial rotatory displacement is known to be a cause of childhood torticollis and may as well be responsible for chronic neck pain after rear-end automobile collisions. The objective was to determine whether quantification of C2 malrotation is possible by plain radiographs in comparison to CT as the golden standard. MR imaging was evaluated as to whether it was of equal value in the detection of bony landmarks. C2 vertebra of five human cadaveric cervical spine specimens, ligamentously intact, were rotated using a Steinmann pin in steps of 5 up to 15 right and 15 left. Plain radiographs, CT and MRI images were taken in each rotational step. Data were analyzed for quantification of C2 rotation by three independent examiners. A rotation of 5 led to a spinous process deviation (SPD) from the midline of 3 mm as measured on an a.p. plain radiograph. A coefficient of rotation was calculated (1.62 mm{sup -1}). Data analyzed by three examiners revealed a small coefficient of variation (0.03). MRI and CT measurements showed comparable results for the quantification of rotation; however, in both techniques the 15 rotation was underestimated. Quantification of upper cervical spine malrotation was possible on plain radiographs using the SPD and a rotation coefficient. MRI and CT were equally successful in the assessment of C2 malrotation. (orig.)

  1. Energy-dispersive small-angle X-ray scattering with cone collimation using X-ray capillary optics

    Science.gov (United States)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi

    2016-09-01

    Energy-dispersive small-angle X-ray scattering (ED-SAXS) with an innovative design of cone collimation based on an ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL) had been explored. Using this new cone collimation system, scattering angle 2θ has a theoretical minimum angle related to the mean half-opening angle of the hollow cone beam of 1.42 mrad, and with the usable X-ray energy ranging from 4 to 30 keV, the resulting observable scattering vector q is down to a minimum value of about 0.003 Å-1 (or a Bragg spacing of about 2100 Å). However, the absorption of lower energies by X-ray capillary optics, sample transmission, and detector response function limits the application range to lower energy. Cone collimation ED-SAXS experiments carried out on pure water, Lupolen, and in situ temperature-dependent measurement of diacetylenic acid/melamine micelle solid were presented at three different scattering angles 2θ of 0.18°, 0.70° and 1.18° to illustrate the new opportunities offered by this technique as well as its limitations. Also, a comparison has been made by replacing the PPXRL with a pinhole, and the result shows that cone collimation ED-SAXS based on ESBC with PPXRL was helpful in improving the signal-to-noise ratio (i.e., reducing the parasitic background scattering) than ESBC with a pinhole. The cone collimation instrument based on X-ray capillary optics could be considered as a promising tool to perform SAXS experiments, especially cone collimation ED-SAXS has potential application for the in situ temperature-dependent studying on the kinetics of phase transitions.

  2. Laser pulse amplification and dispersion compensation in an effectively extended optical cavity containing Bose-Einstein condensates

    CERN Document Server

    Tarhan, Devrim; Mustecaplioglu, Ozgur E; 10.1088/0953-4075/46/1/015501

    2013-01-01

    We review and critically evaluate our proposal of a pulse amplification scheme based on two Bose-Einstein condensates inside the resonator of a mode-locked laser. Two condensates are used for compensating the group velocity dispersion. Ultraslow light propagation through the condensate leads to a considerable increase in the cavity round-trip delay time, lowers the effective repetition rate of the laser, and hence scales up the output pulse energy. It has been recently argued that atom-atom interactions would make our proposal even more efficient. However, neither in our original proposal nor in the case of interactions, limitations due to heating of the condensates by optical energy absorption were taken into account. Our results show that there is a critical time of operation, $~0.3$ ms, for the optimal amplification factor, which is in the order of $\\sim 10^2$ at effective condensate lengths in the order of $\\sim 50$ $\\mu$m. The bandwidth limitation of the amplifier on the minimum temporal width of the pul...

  3. Optical study of the ultrasonic formation process of noble metal nanoparticles dispersed inside the pores of monolithic mesoporous silica

    CERN Document Server

    Fu Gan Hua; Kan Cai Xia; Li Cun Cheng; Fang Qi

    2003-01-01

    Gold nanoparticles dispersed inside the pores of monolithic mesoporous silica were prepared by soaking the silica in a gold (III) ion solution and subsequent ultrasound irradiation. The formation process of gold nanoparticles in the pores of mesoporous silica was investigated based on optical measurements of wrapped and naked soaked silica after ultrasonic irradiation, and the reduction rate effect in solution and pre-soaking effect. It has been shown that acoustic cavitation cannot occur in nano-sized pores. The gold nanoparticles in silica are not formed in situ within the pores but produced mainly by diffusion of the gold clusters formed in the solution during irradiation into the pores. The radicals formed in solution are exhausted before entering the pores of silica. There exists a critical reduction rate in solution, at which the yield of gold nanoparticles in silica reaches a maximum, and above which there is a decrease in the yield. This is attributed to too quick a growth or aggregation of gold clust...

  4. Microstructure and optical dispersion characterization of nanocomposite sol-gel TiO2-SiO2 thin films with different compositions

    Science.gov (United States)

    Kermadi, S.; Agoudjil, N.; Sali, S.; Zougar, L.; Boumaour, M.; Broch, L.; En Naciri, A.; Placido, F.

    2015-06-01

    Nanocomposite TiO2-SiO2 thin films with different compositions (from 0 to 100 mol% TiO2) were deposited by sol-gel dip-coating method on silicon substrate. Crystal structure, chemical bonding configuration, composition and morphology evolutions with composition were followed by Raman scattering, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy respectively. The refractive index and the extinction coefficient were derived in a broad band wavelength (250-900 nm) from spectroscopic ellipsometry data with high accuracy and correlated with composition and microstructure. Results showed an anatase structure for 100% TiO2 with a grain size in 6-10 nm range. Whereas, the inclusion of SiO2 enlarges the optical band gap and suppresses the grain growth up to 4 nm in size. High TiO2 dispersion in SiO2 matrix was observed for all mixed materials. The refractive index (at λ = 600 nm) increases linearly with composition from 1.48 (in 100% SiO2) to 2.22 (in 100% TiO2) leading to lower dense material, its dispersion being discussed in terms of the Wemple-DiDomenico single oscillator model. Hence, the optical parameters, such optical dispersion energies E0 and Ed, the average oscillators, strength S0 and wavelength λ0 and the ratio of the carrier concentration to the effective mass N/m∗ have been derived. The analysis revealed a strong dependence on composition and structure. The optical response was also investigated in term of complex optical conductivity (σ) and both volume and surface energy loss functions (VELF and SELF).

  5. Condylus tertius with atlanto-axial rotatory fixation: an unreported association

    Energy Technology Data Exchange (ETDEWEB)

    Udare, Ashlesha Satish [M.G.M. Hospital, Department of Radiology, Kamothe, Navi Mumbai (India); Global Hospital Super Speciality and Transplant Centre, Department of Radiology, Mumbai (India); Navi Mumbai, Maharashtra (India); Bansal, Divya; Patel, Bhavin [M.G.M. Hospital, Department of Radiology, Kamothe, Navi Mumbai (India); Mondel, Prabath Kumar [P.D. Hinduja Hospital, Department of Radiology, Mahim, Mumbai (India); Aiyer, Siddharth [Shatabdi Hospital, Department of Orthopedics, Chembur, Mumbai (India)

    2014-04-15

    The ''condylus tertius'' or the ''third occipital condyle'' is an embryological remnant of the proatlas sclerotome. Anatomically, it is attached to the basion and often articulates with the anterior arch of the atlas and the odontoid apex; hence, it is also called the ''median occipital condyle''. It is a rare anomaly of the cranio-vertebral junction (CVJ) that can lead to instability and compression of important surrounding neurovascular structures. We report a case of a 16-year-old boy who presented with suboccipital neck pain, torticollis and right sided hemiparesis. Plain radiographs revealed an increased atlanto-dental interspace (ADI) with a retroflexed odontoid. Open mouth view showed asymmetry of the articular processes of the atlas with respect to the dens. Computed tomography (CT) of the CVJ delineated the third occipital condyle. Furthermore, on dynamic CT study, a type 3 atlanto-axial rotatory fixation (AARF) was clearly demonstrated. Magnetic resonance imaging (MRI) of the CVJ revealed severe right-sided spinal cord compression by the retroflexed and rightward deviated dens. It also revealed disruption of the left alar and transverse ligaments. The patient was treated with 8 weeks of cranial traction and reasonable alignment was obtained. This was followed by C1-C2 lateral mass screw fixation and C1-C2 interlaminar wiring to maintain the alignment. A review of the literature did not reveal any cases of condylus tertius associated with non-traumatic AARF. An accurate knowledge of the embryology and imaging features of this rare CVJ anomaly is useful in the prompt diagnosis and management of such patients. (orig.)

  6. Cervical Rotatory Manipulation Decreases Uniaxial Tensile Properties of Rabbit Atherosclerotic Internal Carotid Artery

    Science.gov (United States)

    Qi, Ji; Zhang, Lei; Chen, Chao; Mondal, Shubhro; Ping, Kaike; Chen, Yili

    2017-01-01

    Objective. To investigate the effects of one of the Chinese massage therapies, cervical rotatory manipulation (CRM), on uniaxial tensile properties of rabbit atherosclerotic internal carotid artery (ICA). Methods. 40 male purebred New Zealand white rabbits were randomly divided into CRM-Model group, Non-CRM-Model group, CRM-Normal group, and Non-CRM-Normal group. After modeling (atherosclerotic model) and intervention (CRM or Non-CRM), uniaxial tensile tests were performed on the ICAs to assess the differences in tensile mechanical properties between the four groups. Results. Both CRM and modeling were the main effects affecting physiological elastic modulus (PEM) of ICA. PEM in CRM-Model group was 1.81 times as much as Non-CRM-Model group, while the value in CRM-Model group was 1.34 times as much as CRM-Normal group. Maximum elastic modulus in CRM-Model group was 1.80 times as much as CRM-Normal group. Max strains in CRM-Model group and Non-CRM-Model group were 30.98% and 28.71% lower than CRM-Normal group and Non-CRM-Normal group, respectively. However, whether treated with CRM or not, the uniaxial tensile properties of healthy ICAs were not statistically different. Conclusion. CRM may decrease the uniaxial tensile properties of rabbit arteriosclerotic ICA, but with no effect on normal group. The study will aid in the meaningful explanation of the controversy about the harmfulness of CRM and the suitable population of CRM. PMID:28303160

  7. CT findings and surgical treatment of atlanto-axial rotatory fixation. A case report

    Energy Technology Data Exchange (ETDEWEB)

    Shoji, Akira; Harano, Hideyuki; Okumura, Terufumi (Fukuroi Municipal Hospital, Shizuoka (Japan)); Nakagawa, Hiroshi; Sugiyama, Tadamitsu

    1984-07-01

    A case of atlanto-axial rotatory fixation (AARF) was presented in a 19-year-old female who developed sudden onset of neck pain and limitation of neck movement after direct carotid angiography for seizure disorder. Neurological examination was negative except for cock-robin posture and mild hypesthesia and hypalgesia in left C/sub 2/ distribution. Plain films of the cervical spine disclosed abnormal alignment of C/sub 1/-C/sub 2/ and possible rotational dislocation. Bilateral selective vertebral angiography showed marked anterior and posterior displacement of left and right vertebral artery, respectively, at the level of C/sub 1/. On CT metrizamide myelography, there was clockwise rotation of C/sub 1/ on C/sub 2/ with locked facet on the left but no evidence of cord compression was found. With diagnosis of AARF, manual reduction under general anesthesia and with fluoroscopic control was first attempted without success. Therefore, the patient underwent open reduction by using high speed air-drill and posterior fusion of C/sub 1/ to C/sub 3/ with acryl and wire. Postoperative course was uneventful and the patient went back to work as a computer operator in three months. The etiology of AARF was described by many authors, but in our case, congenital hypogenesis of transverse and alar ligaments plus minor trauma was most suggested. For neurological manifestations of AARF, occipital neuralgia, headache, neck pain, limitation of neck movement and cock-robin posture were reported, but the cock-robin posture was most characteristic and was an important symptom for the early diagnosis. In neuroradiological findings of AARF, plain CT and CT metrizamide myelography are very useful. Because they clearly demonstrate the degree of rotation and interlocking of atlanto-axial joints, and the presence of cord compression.

  8. PMD and chromatic dispersion compensation in a 1.76-terabit/s (44 x 43 Gbit/s) optical transmission experiment over 600-km SMF

    Science.gov (United States)

    Rasmussen, Jens C.

    2004-10-01

    A simple, adaptive PMD compensator is demonstrated in a 1.76Terabit/s (44 x 43 Gbit/s) transmission experi- ment over 600km SMF with a mean PMD of 8 ps. The PMDC is composed of a LiNbO3 polarization-controller followed by a component with an adjustable differential group delay (DGD) in the range of 0-20 ps. Feedback control is provided by means of continuously monitoring and maximizing the degree of polarization (DOP). This PMDC is shown to automatically compensate well for 1st-order (0-28 ps) and one part - the depolarization - of 2nd-order (0-130 ps2) PMD. Polarization dependent chromatic dispersion (PCD), being the other part of 2nd-order PMD, is negligible as long transmission systems without a PMDC are considered. But in fact PCD plays a role when an optical PMDC is introduced. Because of the anyway tight tolerance of 40 Gbit/s optical signals to chromatic dispersion, the variable dispersion compensator VIPA (virtually imaged phased array) with a tuning range of +/-800 ps/nm is introduced besides the PMDC. Therefore, with VIPA not only residual chro- matic dispersion put also PCD is e«ectively compensated for. Using adaptive optical technologies compensating for PMD and chromatic dispersion, error-free transmission (BER< 10í15 with FEC, Q-margin=3 dB) of 44 x 43 Gbit/s (1.76 Tbit/s) over 600km of high PMD (8 ps) SMF is demonstrated.

  9. Unitary version of the single-particle dispersive optical model and single-hole excitations in medium-heavy spherical nuclei

    Science.gov (United States)

    Kolomiytsev, G. V.; Igashov, S. Yu.; Urin, M. H.

    2017-07-01

    A unitary version of the single-particle dispersive optical model was proposed with the aim of applying it to describing high-energy single-hole excitations in medium-heavy mass nuclei. By considering the example of experimentally studied single-hole excitations in the 90Zr and 208Pb parent nuclei, the contribution of the fragmentation effect to the real part of the optical-model potential was estimated quantitatively in the framework of this version. The results obtained in this way were used to predict the properties of such excitations in the 132Sn parent nucleus.

  10. Dispersive liquid–liquid microextraction combined with laser-induced breakdown spectrometry and inductively coupled plasma optical emission spectrometry to elemental analysis

    OpenAIRE

    Gaubeur, Ivanise; Aguirre Pastor, Miguel Ángel; Kovachev, Nikolay; Hidalgo Núñez, Montserrat; Canals Hernández, Antonio

    2015-01-01

    In this paper, two analytical methodologies based on the combination of dispersive liquid–liquid microextraction with inductively coupled plasma optical emission spectrometry and laser-induced breakdown spectrometry, respectively, were evaluated for simultaneous preconcentration and detection of Cd, Co, Ni, Pb and Zn. The microextraction procedure was based on the injection of appropriate quantities of 1-undecanol and methanol into the sample solution containing the complexes formed between m...

  11. Delayed onset of rotatory self-motion perception, dysdiadochokinesia and disturbed eye pursuit caused by low-dose pregabalin

    OpenAIRE

    Hounnou, Patrice; Nicoucar, Keyvan

    2014-01-01

    A 30-year-old woman with chronic foot pain after an orthopaedic surgery and chronic neck pain presented to the emergency department (ED) with a history of self-rotatory vertigo with unsteadiness. She had started low-dose pregabalin, 25 mg two times a day 9 months before experiencing symptoms with the dose gradually increased to 150 mg two times a day over this period. Clinical examination revealed difficulty performing eye pursuit with left eye and dysdiadochokinesia of the left arm. Owing to...

  12. Natural Optical Activity of Chiral Epoxides: the Influence of Structure and Environment on the Intrinsic Chiroptical Response

    Science.gov (United States)

    Lemler, Paul M.; Craft, Clayton L.; Vaccaro, Patrick

    2017-06-01

    Chiral epoxides built upon nominally rigid frameworks that incorporate aryl substituents have been shown to provide versatile backbones for asymmetric syntheses designed to generate novel pharmaceutical and catalytic agents. The ubiquity of these species has motivated the present studies of their intrinsic (solvent-free) circular birefringence (CB), the measurement of which serves as a benchmark for quantum-chemical predictions of non-resonant chiroptical behavior and as a beachhead for understanding the often-pronounced mediation of such properties by environmental perturbations (e.g., solvation). The optical rotatory dispersion (or wavelength-resolved CB) of (R)-styrene oxide (R-SO) and (S,S)-phenylpropylene oxide (S-PPO) have been interrogated under ambient solvated and isolated conditions, where the latter efforts exploited the ultrasensitive techniques of cavity ring-down polarimetry. Both of the targeted systems display marked solvation effects as evinced by changes the magnitude and (in the case of R-SO) the sign of the extracted specific optical rotation, with the anomalously large response evoked from S-PPO distinguishing it from other members of the epoxide family. Linear-response calculations of dispersive optical activity have been performed at both density-functional and coupled-cluster levels of theory to unravel the structural and electronic origins of experimental findings, thereby suggesting the possible involvement of hindered torsional motion along dihedral coordinates adjoining phenyl and epoxide moieties.

  13. Optically active quantum-dot molecules.

    Science.gov (United States)

    Shlykov, Alexander I; Baimuratov, Anvar S; Baranov, Alexander V; Fedorov, Anatoly V; Rukhlenko, Ivan D

    2017-02-20

    Chiral molecules made of coupled achiral semiconductor nanocrystals, also known as quantum dots, show great promise for photonic applications owing to their prospective uses as configurable building blocks for optically active structures, materials, and devices. Here we present a simple model of optically active quantum-dot molecules, in which each of the quantum dots is assigned a dipole moment associated with the fundamental interband transition between the size-quantized states of its confined charge carriers. This model is used to analytically calculate the rotatory strengths of optical transitions occurring upon the excitation of chiral dimers, trimers, and tetramers of general configurations. The rotatory strengths of such quantum-dot molecules are found to exceed the typical rotatory strengths of chiral molecules by five to six orders of magnitude. We also study how the optical activity of quantum-dot molecules shows up in their circular dichroism spectra when the energy gap between the molecular states is much smaller than the states' lifetime, and maximize the strengths of the circular dichroism peaks by optimizing orientations of the quantum dots in the molecules. Our analytical results provide clear design guidelines for quantum-dot molecules and can prove useful in engineering optically active quantum-dot supercrystals and photonic devices.

  14. Optical glass: deviation of relative partial dispersion from the normal line-need for a common definition

    Science.gov (United States)

    Hartmann, Peter

    2015-10-01

    The design of high-quality imaging lenses continues to strive for the best color trueness over wider and wider wavelength ranges such as for multiwavelength fluorescence microscopy or hyperspectral imaging. Glasses suitable for sharp images at more than two wavelengths must differ in their dispersion from the classical crown and flint glass types, which gather along a straight line in a plot of the relative partial dispersion against the Abbe number. Glasses suitable for multicolor correction can be recognized by a considerable deviation of their relative partial dispersion from this normal line. Originally, the normal lines for different relative partial dispersions were defined by using the SCHOTT glass types K7 and F2. Today's data sheets of all glass manufacturers contain numerical values for deviations of relative partial dispersions from the normal lines. A comparison of almost identical glasses shows differences between these deviations being too large, obviously coming from different versions of K7 and F2 dispersion curves used. For preselection in designs and for direct comparison of glass types, it is necessary to agree on common dispersion curves each for K7 and for F2 in order to obtain really comparable values for deviations of the relative partial dispersion from the normal line.

  15. All-optical logic gate based on transient grating from disperse red 1 doped organic-inorganic hybrid films with an improved figure of merit

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Tianxi; Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn; Shao, Jinyou [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, International Center for Dielectric Research, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Wang, Yushu [School of Materials Science and Engineering, Georgia Institute of Technology, 500 Tenth Street NW, Atlanta, Georgia 30318 (United States)

    2015-10-21

    Azobenzene dyes have large refractive index near their main resonance, but the poor figure of merit (FOM) limits their potential for all-optical applications. To improve this situation, disperse red 1 (DR1) molecules were dispersed in a sol-gel germanium/Ormosil organic-inorganic hybrid matrix. Z-scan measurement results showed a good compatibility between the dopant and the matrix, and also, an improved FOM was obtained as compared to the DR1/polymer films reported previously. To demonstrate the all-optical signal processing effect, a cw Nd:YAG laser emitting at 532 nm and a He-Ne laser emitting at 632.8 nm were used as pump and probe beams, respectively. DR1 acts as an initiator of the photo-induced transient holographic grating, which is attributed to the trans-cis-trans photoisomerization. Thus, a three inputs AND all-optical logic gate was achieved by using choppers with different frequencies. The detailed mechanism of operation is discussed. These results indicate that the DR1 doped germanium/Ormosil organic-inorganic hybrid film with an improved FOM has a great potential in all-optical devices around its main resonance.

  16. All-Optical 1-to-8 Wavelength Multicasting at 20 Gbit/s Exploiting Self-Phase Modulation in Dispersion Flattened Highly Nonlinear Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Zhan-Qiang Hui

    2014-01-01

    Full Text Available All-optical multicasting of performing data routing from single node to multiple destinations in the optical domain is promising for next generation ultrahigh-peed photonic networks. Based on the self-phase modulation in dispersion flattened highly nonlinear photonic crystal fiber and followed spectral filtering, simultaneous 1-to-8 all-optical wavelength multicasting return-to-zero (RZ signal at 20 Gbit/s with 100 GHz channel spaced is achieved. Wavelength tunable range and dynamic characteristic of proposed wavelength multicasting scheme is further investigated. The results show our designed scheme achieve operation wavelength range of 25 nm, OSNR of 32.01 dB and Q factor of 12.8. Moreover, the scheme has simple structure as well as high tolerance to signal power fluctuation.

  17. Experimental demonstration of low-complexity fiber chromatic dispersion mitigation for reduced guard-interval OFDM coherent optical communication systems based on digital spectrum sub-band multiplexing.

    Science.gov (United States)

    Malekiha, Mahdi; Tselniker, Igor; Nazarathy, Moshe; Tolmachev, Alex; Plant, David V

    2015-10-05

    We experimentally demonstrate a novel digital signal processing (DSP) structure for reduced guard-interval (RGI) OFDM coherent optical systems. The proposed concept is based on digitally slicing optical channel bandwidth into multiple spectrally disjoint sub-bands which are then processed in parallel. Each low bandwidth sub-band has a smaller delay-spread compared to a full-band signal. This enables compensation of both chromatic dispersion (CD) and polarization mode dispersion using a simple timing and one-tap-per-symbol frequency domain equalizer with a small cyclic prefix overhead. In terms of the DSP architecture, this allows for a highly efficient parallelization of DSP tasks performed over the received signal samples by deploying multiple processors running at a lower clock rate. It should be noted that this parallelization is performed in the frequency domain and it allows for flexible optical transceiver schemes. In addition, the resulting optical receiver is simplified due to the removal of the CD compensation equalizer compared to conventional RGI-OFDM systems. In this paper we experimentally demonstrate digital sub-banding of optical bandwidth. We test the system performance for different modulation formats (QPSK, 16QAM and 32QAM) over various transmission distances and optical launch powers using a 1.5% CP overhead in all scenarios. We also compare the proposed RGI-OFDM architecture performance against common single carrier modulation formats. At the same total data rate and signal bandwidth both systems have similar performance and transmission reach whereas the proposed method allows for a significant reduction of computational complexity due to removal of CD pre/post compensation equalizer.

  18. Implications for (d,p) reaction theory from nonlocal dispersive optical model analysis of $^{40}$Ca(d,p)$^{41}$Ca

    CERN Document Server

    Waldecker, S J

    2016-01-01

    The nonlocal dispersive optical model (NLDOM) nucleon potentials are used for the first time in the adiabatic analysis of a (d,p) reaction to generate distorted waves both in the entrance and exit channels. These potentials were designed and fitted by Mahzoon $et \\text{ } al.$ [Phys. Rev. Lett. 112, 162502 (2014)] to constrain relevant single-particle physics in a consistent way by imposing the fundamental properties, such as nonlocality, energy-dependence and dispersive relations, that follow from the complex nature of nuclei. However, the NLDOM prediction for the $^{40}$Ca(d,p)$^{41}$Ca cross sections at low energy, typical for some modern radioactive beam ISOL facilities, is about 70$\\%$ higher than the experimental data despite being reduced by the NLDOM spectroscopic factor of 0.73. This overestimation comes most likely either from insufficient absorption or due to constructive interference between ingoing and outgoing waves. This indicates strongly that additional physics arising from many-body effects ...

  19. INFLUENCE OF CHROMATIC DISPERSION, DISPERSION SLOPE, DISPERSION CURVATURE ON MICROWAVE GENERATION USING TWO CASCADE MODULATORS

    OpenAIRE

    Mandeep Singh; S.K. Raghuwanshi

    2013-01-01

    This work presents a theoretical study of harmonic generation of microwave signals after detection of a modulated optical carrier in cascaded two electro-optic modulators. Dispersion is one of the major limiting factors for microwave generation in microwave photonics. In this paper, we analyze influence of chromatic dispersion, dispersion slope, dispersion curvature on microwave generation using two cascaded MZMs and it has been found that output intensity of photodetector reduces when disper...

  20. Dispersion management with metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Tassin, Philippe; Koschny, Thomas; Soukoulis, Costas M.

    2017-03-07

    An apparatus, system, and method to counteract group velocity dispersion in fibers, or any other propagation of electromagnetic signals at any wavelength (microwave, terahertz, optical, etc.) in any other medium. A dispersion compensation step or device based on dispersion-engineered metamaterials is included and avoids the need of a long section of specialty fiber or the need for Bragg gratings (which have insertion loss).

  1. A new chiral residue analysis method for triazole fungicides in water using dispersive liquid-liquid microextraction (DLLME).

    Science.gov (United States)

    Luo, Mai; Liu, Donghui; Zhou, Zhiqiang; Wang, Peng

    2013-09-01

    A rapid, simple, reliable, and environment-friendly method for the residue analysis of the enantiomers of four chiral fungicides including hexaconazole, triadimefon, tebuconazole, and penconazole in water samples was developed by dispersive liquid-liquid microextraction (DLLME) pretreatment followed by chiral high-performance liquid chromatography (HPLC)-DAD detection. The enantiomers were separated on a Chiralpak IC column by HPLC applying n-hexane or petroleum ether as mobile phase and ethanol or isopropanol as modifier. The influences of mobile phase composition and temperature on the resolution were investigated and most of the enantiomers could be completely separated in 20 min under optimized conditions. The thermodynamic parameters indicated that the separation was enthalpy-driven. The elution orders were detected by both circular dichroism detector (CD) and optical rotatory dispersion detector (ORD). Parameters affecting the DLLME performance for pretreatment of the chiral fungicides residue in water samples, such as the extraction and dispersive solvents and their volume, were studied and optimized. Under the optimum microextraction condition the enrichment factors were over 121 and the linearities were 30-1500 µg L(-1) with the correlation coefficients (R(2)) over 0.9988 and the recoveries were between 88.7% and 103.7% at the spiking levels of 0.5, 0.25, and 0.05 mg L(-1) (for each enantiomer) with relative standard deviations varying from 1.38% to 6.70% (n = 6) The limits of detection (LODs) ranged from 8.5 to 29.0 µg L(-1) (S/N = 3).

  2. Dispersion compensation of a 1x N passive optical router with low loss, a flat passband, and low cross talk.

    Science.gov (United States)

    Leick, L; Madsen, C K

    2002-08-01

    A 1xN interferometer-based router with single-stage all-pass filters in the arms has low loss, a flat passband, and low cross talk. However, we show that the router has substantial cubic dispersion over the channel passband, which is identical from channel to channel. For a 1x4 router with a free spectral range of 100 GHz, the average dispersion slope over a 60% passband is -8x10(3)ps/nm(2), and thus a cascade of four routers incurs a significant system power penalty. A three-stage all-pass filter placed on the input arm reduces the dispersion of all channels by a factor of 16. The router is quite insensitive to variations in the all-pass filter design parameters.

  3. The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for MaxBCG Galaxy Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Becker, M.R.; McKay, T.A.; /Michigan U.; Koester, B.; /Chicago U., Astron. Astrophys. Ctr.; Wechsler, R.H.; /KIPAC, Menlo Park /SLAC /Stanford U., Phys. Dept.; Rozo, E.; /Ohio State U.; Evrard, A.; /Michigan U. /Michigan U., MCTP; Johnston, D.; /Caltech, JPL; Sheldon, E.; /New York U.; Annis, J.; /Fermilab; Lau, E.; /Chicago U., Astron. Astrophys. Ctr.; Nichol, R.; /Portsmouth U., ICG; Miller, C.; /Michigan U.

    2007-06-05

    The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG--galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202 {+-} 10 km s{sup -1} for small groups to more than 854 {+-} 102 km s{sup -1} for large clusters. We show the scatter to be at most 40.5{+-}3.5%, declining to 14.9{+-}9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass--observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.

  4. Influence of the Wavelength Dependence of Birefringence in the Generation of Supercontinuum and Dispersive Wave in Fiber Optics

    Directory of Open Access Journals (Sweden)

    Rodrigo Acuna Herrera

    2017-01-01

    Full Text Available In this paper, we perform numerical analysis about the influence of the wavelength dependence of birefringence (WDB in the Supercontinuum (SC and dispersive wave (DW generation. We study different birefringence profiles such as constant, linear, and parabolic. We see that, for a linear and parabolic profile, the generation of SC practically does not change, while this does so when the constant value of the birefringence varies. Similar situation happens with the generation of dispersive waves. In addition, we observe that the broadband of the SC increases when the Stimulated Raman Scattering (SRS is neglected for all WDB profiles.

  5. Adult Case of Atlantoaxial Rotatory Fixation Treated with In Situ Fixation Using an Unusual Posterior Instrumentation Construct.

    Science.gov (United States)

    Miyao, Yasuyoshi; Sasaki, Manabu; Umegaki, Masao; Yonenobu, Kazuo

    2017-07-01

    Atlantoaxial rotatory fixation (AARF) occurs commonly in children who have undergone trauma. It is usually corrected with conservative therapy. In this report, however, the patient was an adult with AARF who was treated surgically. A 64-year-old woman presented with a 1-year history of spastic gait and hand clumsiness. Imaging studies revealed the presence of AARF, os odontoideum, and severe spinal cord compression at that spinal level. As the AARF had not been responded to head traction with a halo device, we decided to treat the patient with in situ posterior fixation. Because the rigid dislocation was present between the atlas and the axis, we were forced to make an unusual instrumentation construct. Neurological symptoms other than hand numbness diminished after the surgery, and arthrodesis was obtained between the occiput and the axis. It should be noted that surgical planning for posterior instrumentation construct is required when rigid AARF is treated surgically.

  6. JOSA COMMUNICATIONS: Stabilization of soliton trains in optical fibers in the presence of third-order dispersion

    Science.gov (United States)

    Uzunov, I. M.; Gölles, M.; Lederer, F.

    1995-06-01

    We analyze the propagation of soliton trains with small initial separation in the presence of third-order dispersion. We show that both the amplitudes and the positions can be stabilized, provided that phase modulation is applied and adjacent pulses are initially out of phase.

  7. Optical constants, single-oscillator modal and refractive index dispersion analysis of lithium zinc bismuth borate glasses doped with Eu{sup 3+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Boda, Ramesh; Srinivas, G.; Komaraiah, D.; Srinivas, B.; Shareefuddin, Md.; Sayanna, R. [Department of physics, Osmania University, Hyderabad-07, Telangana, India. (India)

    2016-05-06

    The glasses of composition xLi{sub 2}O-15ZnO- 20Bi{sub 2}O{sub 3}- (64 - x) B{sub 2}O{sub 3}- 1EuO (ZLB) (where x=0, 5, 10, 15, 20 mole %) prepared by melt-quenching technique. The amorphous nature of the prepared glasses was confirmed by XRD spectra. The UV-Vis optical absorption spectrum was recorded in the wave length range of 200-1000 nm. It is observed that the optical band gap is inversely changing with Urbach energy. The optical constants such as G (a constant proportional to the second-order deformation potential) and E{sub f} (a constant that depends on local coordination and is called as free energy of the glass system). The most significant result of the present work is the refractive index dispersion curves of the ZLB glasses obey the single-oscillator model and oscillator parameters (E{sub o}, E{sub d}) changed with the Li{sub 2}O content. the absorption edge, band gap and Urbach energy is changing nonlinearly with increasing content of Li{sub 2}O, which can be used to calculate the optical, physical, and other constants.

  8. Effects of Temperature and Axial Strain on Four-Wave Mixing Parametric Frequencies in Microstructured Optical Fibers Pumped in the Normal Dispersion Regime

    Directory of Open Access Journals (Sweden)

    Javier Abreu-Afonso

    2014-10-01

    Full Text Available A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the appearance of two widely-spaced four-wave mixing spectral bands. Temperature changes, and/or axial strain applied to the fiber, affects the dispersion characteristics of the fiber, which can result in the shift of the parametric wavelengths. We show that the increase of temperature causes the signal and idler wavelengths to shift linearly towards shorter and longer wavelengths, respectively. For the specific fiber of the experiment, the band shift at rates ­–0.04 nm/ºC and 0.3 nm/ºC, respectively. Strain causes the parametric bands to shift in the opposite way. The signal band shifted 2.8 nm/me and the idler -5.4 nm/me. Experimental observations are backed by numerical simulations.

  9. A proposal for digital electro-optic switches with free-carrier dispersion effect and Goos-Hanchen shift in silicon-on-insulator waveguide corner mirror

    Science.gov (United States)

    Sun, DeGui

    2013-09-01

    In a silicon-on-insulator (SOI) waveguide corner mirror (WCM) structure, with the quantum process of a frustrated total internal reflection (FTIR) phenomenon and the time delay principle in the two-dimensional potential barrier tunneling process of a mass of particles, we derive an accurate physical model for the Goos-Hanchen (GH) shift of optical guided-mode in the FTIR process, and in principle match the GH shift jumping states with the independent guided-modes. Then, we propose and demonstrate a new regime of 1 × N digital optical switches with a matching state between the free-carrier dispersion (FCD) based refractive index modulation (RIM) of silicon to create a GH shift jumping function of a photonic signal at the reflecting interface and the independent guided-modes in the FTIR process, where a MOS-capacitor type electro-optic modulation regime is proposed and discussed to realize an effective FCD-based RIM. At the critical matching state, i.e., the incident of an optical beam is at the vicinity of Brewster angle in the WCM, a mini-change of refractive index of waveguide material can cause a great jump of GH shift along the FTIR reflecting interface, and further a 1 × N digital optical switching process could be realized. For a 350-500 nm single-mode rib waveguide made on the 220 nm CMOS-compatible SOI substrate and with the FCD effect based RIM of silicon crystal, a concentration variation of 1018-1019 cm-3 has caused a 0.5-2.5 μm GH shift of reflected beam, which is at 2-5 times of a mode-size and hence radically convinces an optical switching function with a 1 × 3-1 × 10 scale.

  10. Determination of optical constant and dispersion parameters of Se75Sb10In15 thin film characterized by wide band gap

    Science.gov (United States)

    Abd-Elrahman, M. I.; Abu-Sehly, A. A.; El-sonbaty, Sherouk Sh.; Hafiz, M. M.

    2017-02-01

    Chalcogenide Se75Sb10In15 thin films of different thickness (50-300 nm) are deposited using thermal evaporation technique. The thermogram of the chalcogenide bulk Se75Sb10In15 is obtained using a differential scanning calorimetry (DSC). The crystallization temperature T c, peak crystallization temperature T p and melting temperature T m, are identified. The X-ray diffraction (XRD) examination indicates the crystallinity of the as-deposited film decreases with increasing of thickness. Optical transmission and reflection spectra are recorded in the wavelength range of the incident photons from 250 to 2500 nm. It is found that the film thickness affects the absorption coefficient, refractive index, extinction coefficient and the width of the tails of localized states in the gap region. The absorption mechanism of the as-deposited films is a direct allowed transition. The optical band gap energy ( E g) decreases from 3.31 to 2.51 eV with increasing the film thickness from 50 to 300 nm. The behavior of E g is explained on the basis of the structure disorders in the thicker films. The effect of the film thickness on the single-oscillator and dispersion energies is studied by the dispersion analyses of the refractive index.

  11. Determination of optical constant and dispersion parameters of Se{sub 75}Sb{sub 10}In{sub 15} thin film characterized by wide band gap

    Energy Technology Data Exchange (ETDEWEB)

    Abd-Elrahman, M.I.; Abu-Sehly, A.A.; El-sonbaty, Sherouk Sh.; Hafiz, M.M. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt)

    2017-02-15

    Chalcogenide Se{sub 75}Sb{sub 10}In{sub 15} thin films of different thickness (50-300 nm) are deposited using thermal evaporation technique. The thermogram of the chalcogenide bulk Se{sub 75}Sb{sub 10}In{sub 15} is obtained using a differential scanning calorimetry (DSC). The crystallization temperature T{sub c}, peak crystallization temperature T{sub p} and melting temperature T{sub m}, are identified. The X-ray diffraction (XRD) examination indicates the crystallinity of the as-deposited film decreases with increasing of thickness. Optical transmission and reflection spectra are recorded in the wavelength range of the incident photons from 250 to 2500 nm. It is found that the film thickness affects the absorption coefficient, refractive index, extinction coefficient and the width of the tails of localized states in the gap region. The absorption mechanism of the as-deposited films is a direct allowed transition. The optical band gap energy (E{sub g}) decreases from 3.31 to 2.51 eV with increasing the film thickness from 50 to 300 nm. The behavior of E{sub g} is explained on the basis of the structure disorders in the thicker films. The effect of the film thickness on the single-oscillator and dispersion energies is studied by the dispersion analyses of the refractive index. (orig.)

  12. Narrow Bandwidth Faraday Anomalous Dispersion Optical Filter%窄带 Faraday 反常色散光学滤波器

    Institute of Scientific and Technical Information of China (English)

    刘阳; 王健; 王海华; 康智慧; 王磊; 罗梦希; 闫西章; 王潇潇; 高锦岳

    2014-01-01

    研究 Faraday 反常色散光学滤波器,给出其理论计算过程和模拟结果。结果表明, Faraday反常色散光学滤波器有线翼和线芯透过两种工作方式,其中线翼透过单峰谱线线宽约为600 MHz,透过率约为25%,线芯透过谱线线宽约为700 MHz,透过率约为100%。实验结果与理论结果相符。%To obtain the weak signal light from the high background light,a narrow bandwidth Faraday anomalous dispersion optical filter (FADOF)was studied.The theoretical model for the filter was reported.The Faraday anomalous dispersion optical filters have two working modes:two side peak transmission and center peak transmission.The former work mode can get single peak transmission of 25% with a bandwidth of about 600 MHz.The other work mode can get a spectra with a transmission rate of almost 100% and a bandwith of about 700 MHz.The experimental measurements are consistent with theoretical results.

  13. Influence of Shell Formation on Morphological Structure, Optical and Emission Intensity on Aqueous Dispersible NaYF4:Ce/Tb Nanoparticles.

    Science.gov (United States)

    Ansari, Anees A; Parchur, A K; Kumar, B; Rai, S B

    2016-07-01

    A highly water-dispersible NaYF4:Ce/Tb (core), NaYF4:Ce/Tb@NaYF4(core/shell) and NaYF4:Ce/Tb@NaYF4@SiO2 (core/shell/SiO2) nanoparticles (NPs) were synthesized via a general synthesis approach. The growth of an inert NaYF4 and silica shell (~14 nm) around the core-NPs resulted in an increase of the average size of the nanopaticles as well as broadening of their size distribution. The optical band-gap energy slightly decreases after shell formation due to the increase the crystalline size. To optimize the influence of shell formation a comparative analysis of photoluminescence properties (excitation, emission, and luminescence decay time) of the core, core/shell, and core/shell/SiO2 NPs were measured. The emission intensity was significantly enhanced after inert shell formation around the surface of the core NPs. The Commission International de l'Eclairage chromaticity coordinates of the emission spectrum of core, core/shell, core/shell/SiO2 NPs lie closest to the standard green color emission at 545 nm. By quantitative spectroscopic measurements of surface-modified core-NPs, it was suggested that encapsulation with inert and silica layers was found to be effective in retaining both luminescence intensity and dispersibility in aqueous environment. Considering the high aqueous dispersion and enhanced luminescence efficiency of the core-NPs make them an ideal luminescent material for luminescence bioimaging and optical biosensors.

  14. Assessment of Fiber Chromatic Dispersion Based on Elimination of Second-Order Harmonics in Optical OFDM Single Sideband Modulation Using Mach Zehnder Modulator

    Science.gov (United States)

    Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

    2016-07-01

    This work addresses the analytical and numerical investigations of the transmission performance of an optical Single Sideband (SSB) modulation technique generated by a Mach Zehnder Modulator (MZM) with a 90° and 120° hybrid coupler. It takes into account the problem of chromatic dispersion in single mode fibers in Passive Optical Networks (PON), which severely degrades the performance of the system. Considering the transmission length of the fiber, the SSB modulation generated by maintaining a phase shift of π/2 between the two electrodes of the MZM provides better receiver sensitivity. However, the power of higher-order harmonics generated due to the nonlinearity of the MZM is directly proportional to the modulation index, making the SSB look like a quasi-double sideband (DSB) and causing power fading due to chromatic dispersion. To eliminate one of the second-order harmonics, the SSB signal based on an MZM with a 120° hybrid coupler is simulated. An analytical model of conventional SSB using 90° and 120° hybrid couplers is established. The latter suppresses unwanted (upper/lower) first-order and second-order (lower/upper) sidebands. For the analysis, a varying quadrature amplitude modulation (QAM) Orthogonal Frequency Division Multiplexing (OFDM) signal with a data rate of 5 Gb/s is upconverted using both of the SSB techniques and is transmitted over a distance of 75 km in Single Mode Fiber (SMF). The simulation results show that the SSB with 120° hybrid coupler proves to be more immune to chromatic dispersion as compared to the conventional SSB technique. This is in tandem with the theoretical analysis presented in the article.

  15. Characterization of the optical constants and dispersion parameters of chalcogenide Te40Se30S30 thin film: thickness effect

    Science.gov (United States)

    Abd-Elrahman, M. I.; Hafiz, M. M.; Qasem, Ammar; Abdel-Rahim, M. A.

    2016-02-01

    Chalcogenide Te40Se30S30 thin films of different thickness (100-450 nm) are prepared by thermal evaporation of the Te40Se30S30 bulk. X-ray examination of the film shows some prominent peaks relate to crystalline phases indicating the crystallization process. The calculated particles of crystals from the X-ray diffraction peaks are found to be from 11 to 26 nm. As the thickness increases, the transmittance decreases and the reflectance increases. This could be attributed to the increment of the absorption of photons as more states will be available for absorbance in the case of thicker films. The decrease in the direct band gap with thickness is accompanied with an increase in energy of localized states. The obtained data for the refractive index could be fit to the dispersion model based on the single oscillator equation. The single-oscillator energy decreases, while the dispersion energy increases as the thickness increases.

  16. Evidence for a dispersion relation of optical modes in the cuticle of the scarab beetle Cotinis mutabilis

    OpenAIRE

    Mendoza, Arturo; Muñoz-Pineda, Eloy; Järrendahl, Kenneth; Arwin, Hans

    2014-01-01

    Variable angle Mueller matrix spectroscopic ellipsometry is used to study the properties of light reflected from the exoskeleton (cuticle) of the scarab beetle Cotinis mutabilis. For unpolarized incident light, the ellipticity and degree of polarization of the reflected light reveal a lefthanded helical structure in the beetle cuticle. Analysis of the spectral position of the maxima and minima in the interference oscillations of the Mueller-matrix elements provides evidence for a dispersion r...

  17. 聚合物分散液晶膜的压光效应%Piezo-Optical Effect of Polymer Dispersed Liquid Crystal Films

    Institute of Scientific and Technical Information of China (English)

    范志新; 解一军; 魏向东; 解会杰; 宋新华; 王丹; 孙玉宝

    2011-01-01

    报道了一种聚合物分散液晶(PDLC)膜在压力作用下从散射膜变为透明膜的实验现象,建议称之为PDLC膜的压光效应.介绍了与压光效应相关的PDLC的应变液晶、剪切液晶和拉伸液晶等概念;给出PDLC压光效应膜样品照片,偏光显微镜照片,电光特性光谱分析和压光效应光谱分析.提出PDLC膜压光效应的原理猜想,给出对PDLC膜光学性质的重新认识,认为只要每个液晶微滴中液晶分子取向一致了,无论不同微滴间液晶分子取向一致与否,PDLC膜都将透明.PDLC膜压光效应将对液晶基础科学提出新课题,将在许多不用加电的新型压光器件(按压窗、功能玻璃和光纤压力传感器等)领域有应用前景.%It is reported that polymer dispersed liquid crystal (PDLC) films are transparency when pressed, and it is called piezo-optical effect of PDLC films. The concepts of stressed liquid crystal, sheared liquid crystal and stretched liquid crystal for PDLC films are described respectively. The pictures of piezo-optical effect, polarized photographs of PDLC films, spectral analysis of electro-optical property and spectral analysis of piezo-optical effect are given. The principle of piezo-optical effect of PDLC films is also proposed, which believes that only if liquid crystal molecules in each micro-droplet are well orientated, the PDLC films will show transparency, no matter liquid crystal molecules in different droplets are well orientated or not. The piezo-optical effect of PDLC films poses questions to basic sciences of liquid crystal and may be applied in a lot of new press-optical applications without electricity (press-windows,functional glass, optical fiber press sensor, etc. ).

  18. Dispersion of the linear and nonlinear optical susceptibilities of the CuAl(S{sub 1–x}Se{sub x})₂ mixed chaclcopyrite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A. H., E-mail: maalidph@yahoo.com [New Technologies - Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Brik, M. G. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14C, Tartu 50411 (Estonia); Auluck, S. [Council of Scientific and Industrial Research—National Physical Laboratory Dr. K S Krishnan Marg, New Delhi 110012 (India)

    2014-09-14

    Based on the electronic band structure, we have calculated the dispersion of the linear and nonlinear optical susceptibilities for the mixed CuAl(S{sub 1–x}Se{sub x})₂ chaclcopyrite compounds with x=0.0, 0.25, 0.5, 0.75, and 1.0. Calculations are performed within the Perdew-Becke-Ernzerhof general gradient approximation. The investigated compounds possess a direct band gap of about 2.2 eV (CuAlS₂), 1.9 eV (CuAl(S₀.₇₅Se₀.₂₅)₂), 1.7 eV (CuAl(S₀.₅Se₀.₅)₂), 1.5 eV (CuAl(S₀.₂₅Se₀.₇₅)₂), and 1.4 eV (CuAlSe₂) which tuned to make them optically active for the optoelectronics and photovoltaic applications. These results confirm that substituting S by Se causes significant band gaps' reduction. The optical function's dispersion ε₂{sup xx}(ω) and ε₂{sup zz}(ω)/ε₂{sup xx}(ω), ε₂{sup yy}(ω), and ε₂{sup zz}(ω) was calculated and discussed in detail. To demonstrate the effect of substituting S by Se on the complex second-order nonlinear optical susceptibility tensors, we performed detailed calculations for the complex second-order nonlinear optical susceptibility tensors, which show that the neat parents compounds CuAlS₂ and CuAlSe₂ exhibit | χ₁₂₂²}(-2ω;ω;ω) | as the dominant component, while the mixed alloys exhibit | χ₁₁₁²(-2ω;ω;ω) | as the dominant component. The features of | χ₁₂₃²}(-2ω;ω;ω) | and | χ{sub 111}²}(-2ω;ω;ω) | spectra were analyzed on the basis of the absorptive part of the corresponding dielectric function ε₂(ω) as a function of both ω/2 and ω.

  19. Analytical Investigations on Carrier Phase Recovery in Dispersion-Unmanaged n-PSK Coherent Optical Communication Systems

    OpenAIRE

    Tianhua Xu; Gunnar Jacobsen; Sergei Popov; Jie Li; Tiegen Liu; Yimo Zhang; Polina Bayvel

    2016-01-01

    Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n-PSK) optical fiber communication systems, involving a one-tap normalized least-mean-square (LMS) al...

  20. Optical band gap and refractive index dispersion parameters of As x Se70Te30- x (0≤ x≤30 at.%) amorphous films

    Science.gov (United States)

    Aly, Kamal A.

    2010-06-01

    Amorphous As x Se70Te30- x thin films with (0≤ x≤30 at.%) were deposited onto glass substrates by using thermal evaporation method. The transmission spectra T( λ) of the films at normal incidence were measured in the wavelength range 400-2500 nm. A straightforward analysis proposed by Swanepoel based on the use of the maxima and minima of the interference fringes has been used to drive the film thickness, d, the complex index of refraction, n, and the extinction coefficient, k. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple and DiDomenico model (WDD). Increasing As content is found to affect the refractive index and the extinction coefficient of the As x Se70Te30- x films. With increasing As content the optical band gap increases while the refractive index decreases. The optical absorption is due to allowed indirect transition. The chemical bond approach has been applied successfully to interpret the increase of the optical gap with increasing As content.

  1. First-Order-Like Phase Transition Induced by Two Different Kinds of Noise in Dispersive Optical Bistability

    Institute of Scientific and Technical Information of China (English)

    HE Ying; ZHU Shi-Qun

    2003-01-01

    With unified colored noise approximation, the steady state distribution function in dispersive opticalbistability including both intensity and phase fluctuations is obtained. The parameter plane of the first-order-like phasetransition is also derived with numerical method. It is found that the number of extremes at non-zero values of theoutput field in the steady state distribution function is changed from zero, two to four. It is shown that the strengths of the intensity fluctuation and the phase fluctuation have great effect on the first-order-like phase transition.

  2. Type of tunable guided-mode resonance filter based on electro-optic characteristic of polymer-dispersed liquid crystal.

    Science.gov (United States)

    Wang, Qi; Zhang, Dawei; Huang, Yuanshen; Ni, Zhengji; Chen, Jiabi; Zhong, Yangwan; Zhuang, Songlin

    2010-04-15

    A narrowband guided-mode resonance filter (GMRF) incorporating polymer-dispersed liquid crystal (PDLC) is designed. Simulating the characteristics of the filter with rigorous coupled-wave analysis, we find that the resonance wavelength of the new kind of GMRF can be tuned from 672.4 to 698.4 nm by varying the refractive index of the PDLC layer with the applied voltage. Furthermore, the resonance wavelengths vary in a linear fashion with respect to the refractive index of the PDLC layer. Therefore, the desired resonance wavelength can be conveniently selected and tuned in a tuning range of 26 nm by using the applied voltage.

  3. Determination of the far infrared optical constants of η-doped bulk CdxHg1-xTe (CMT) by dispersive fourier transform spectroscopy

    Science.gov (United States)

    Shayesteh, S. Farjami; Dumelow, T.; Parker, T. J.; Benushis, T. I.; Ershov, S. N.; Vasilevskiy, M. I.

    1995-04-01

    Far infrared phase and amplitude reflectivity measurements have been made on two bulk CdxHg1-xTe mixed crystals with composition x=0.29 and x=0.22 by dispersive Fourier transform spectroscopy (DFTS). The results have been used to calculate the real and imaginary parts of the dielectric function (ɛ', ɛ″) from the Fresnel relations. A plasma contribution is observed in the spectra in addition to the phonon response. For both samples a broad but weak reflection band around 95 105 cm-1 is observed as well as the expected two-oscillator response from the HgTe-like and CdTe-like optical phonons. This feature is attributed to absorption due to phonon combination bands, but it is too broad to enable assignments to be made. There is no evidence of additional features in the CdTe region due to clustering.

  4. Electro-optical response of polymer-dispersed liquid crystal single layers of large nematic droplets oriented by rubbed teflon nanolayers

    Science.gov (United States)

    Marinov, Y. G.; Hadjichristov, G. B.; Petrov, A. G.; Marino, S.; Versace, C.; Scaramuzza, N.

    2013-02-01

    The surface orienting effect of rubbed teflon nanolayers on the morphology and electro-optical (EO) response of polymer-dispersed liquid crystal (PDLC) single layers of large nematic droplets was studied experimentally. In PDLC composites of the nematic liquid crystal (LC) E7 and NOA65 polymer, single droplets of LC with diameters as larger as 10 μm were confined in layers with a thickness of 10 μm, and the nematic director field was efficiently modified by nanostructuring teflon rubbing of the glass plates of the PDLC cell. For layered PDLCs arranged and oriented in this way, the modulated EO response by the dielectric oscillations of the nematic director exhibits a selective amplitude-frequency modulation controllable by both temperature and voltage applied, and is simply related to the LC droplet size. That may be of practical interest for PDLC-based modulators operating in the infrasound frequency range.

  5. Dark optical, singular solitons and conservation laws to the nonlinear Schrödinger’s equation with spatio-temporal dispersion

    Science.gov (United States)

    Inc, Mustafa; Aliyu, Aliyu Isa; Yusuf, Abdullahi

    2017-05-01

    This paper studies the dynamics of solitons to the nonlinear Schrödinger’s equation (NLSE) with spatio-temporal dispersion (STD). The integration algorithm that is employed in this paper is the Riccati-Bernoulli sub-ODE method. This leads to dark and singular soliton solutions that are important in the field of optoelectronics and fiber optics. The soliton solutions appear with all necessary constraint conditions that are necessary for them to exist. There are four types of nonlinear media studied in this paper. They are Kerr law, power law, parabolic law and dual law. The conservation laws (Cls) for the Kerr law and parabolic law nonlinear media are constructed using the conservation theorem presented by Ibragimov.

  6. Density of electronic states and dispersion of optical functions of defect chalcopyrite CdGa{sub 2}X{sub 4} (X = S, Se): DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H. [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Khan, Saleem Ayaz, E-mail: sayaz_usb@yahoo.com [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic)

    2013-11-15

    Graphical abstract: - Highlights: • FPLAPW method is used for calculating the electronic and optical properties of CdGa{sub 2}X{sub 4}. • Electronic and optical properties were calculated using LDA, GGA, EVGGA and mBJ. • Band gap conformed that CdGa{sub 2}X{sub 4} are semiconductors fit for UV and visible light. • The ECD shows that change in the bond length and bond nature affect the band gap. • The dielectric tensor components and its derivatives show considerable anisotropy. - Abstract: A density functional theory (DFT) based on full potential linear augmented plane wave (FPLAPW) was used for calculating the electronic structure, charge density and optical properties of CdGa{sub 2}X{sub 4} (X = S, Se) compounds. Local density approximation (LDA), generalized gradient approximation (GGA), Engle Vasko generalized gradient approximation (EVGGA) and recently modified Becke–Johnson (mBJ) were applied to calculate the band structure, total and partial density of states. The investigation of band structures and density of states of CdGa{sub 2}X{sub 4} (X = S, Se) elucidate that mBJ potential show close agreement to the experimental results. The mBJ potential was selected for further explanation of optical properties of CdGa{sub 2}X{sub 4} (X = S, Se). The study of electronic charge density contours shows that change in the bond lengths and bond nature affect the band gap of the compounds. The two non-zero dielectric tensor components and its derivatives show considerable anisotropy between the perpendicular and parallel components. The present work provide accurate information about the combination (hybridization) of orbital, formation of bands and dispersion of non-zero tensor components of CdGa{sub 2}X{sub 4} (X = S, Se)

  7. Chromatic dispersion monitoring and adaptive compensation using pilot symbols in an 8 x 12.5 Gbit/s all-optical OFDM system.

    Science.gov (United States)

    Shimizu, Satoshi; Cincotti, Gabriella; Wada, Naoya

    2014-04-07

    We propose and experimentally demonstrate a novel technique for chromatic dispersion (CD) monitoring and adaptive compensation in an 8 x 12.5 Gbit/s all-optical orthogonal frequency-division multiplexing (AO-OFDM) system by using two pilot symbols and a virtually imaged phased array (VIPA) for a tunable CD compensator. The two pilot symbols are added to the first and the last sub-channels of the OFDM signal, and their relative time delay is detected and used for CD estimation at the CD monitoring circuit. The monitored CD value is fed to VIPA for CD compensation. In the experiments, the relative time delay between the two pilot symbols was successfully observed, and the adaptive CD compensation drastically improved the bit-error-rate (BER) from over 10(-5) to under 10(-9). The estimated CD values showed less than 10 ps/nm difference from the values measured by a photonic dispersion analyzer, which is accurate enough since the AO-OFDM system can keep BER<10(-9) upto 20 ps/nm residual CD.

  8. Phonon States and Dispersive Spectra of Polar Optical Phonons in Quasi-One-Dimensional Nanowires of Wurtzite ZnO and Zinc-Blend MgO Semiconductors*

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li

    2011-01-01

    Within the framework of the macroscopic dielectric continuum model and Loudon's uniaxial crystal model,the phonon modes of a wurtzite/zinc-blende one-dimensional (ID) cylindrical nanowire (NW) are derived and studied.The analytical phonon states of phonon modes are given.It is found that there exist two types of polar phonon modes,i.e.interface optical (IO) phonon modes and the quasi-confined (QC) phonon modes existing in 1D wurtzite/zinc-blende NWs.Via the standard procedure of field quantization, the Frohlich electron-phonon interaction Hamiltonians are obtained.Numerical calculations of dispersive behavior of these phonon modes on a wurtzite/zinc-blende ZnO/MgO NW are performed.The frequency ranges of the I0 and QC phonon modes of the ZnO/MgO NWs are analyzed and discussed.It is found that the IO modes only exist in one frequency range, while QC modes may appear in three frequency ranges.The dispersive properties of the IO and QC modes on the free wave-number kz and the azimuthal quantum number m are discussed.The analytical Hamiltonians of electron-phonon interaction obtained here are quite useful for further investigating phonon influence on optoelectronics properties of wurtzite/zinc-blende 1D NW structures.

  9. Dispersive response of atoms trapped near the surface of an optical nanofiber with applications to quantum nondemolition measurement and spin squeezing

    Science.gov (United States)

    Qi, Xiaodong; Baragiola, Ben Q.; Jessen, Poul S.; Deutsch, Ivan H.

    2016-02-01

    We study the strong coupling between photons and atoms that can be achieved in an optical nanofiber geometry when the interaction is dispersive. While the Purcell enhancement factor for spontaneous emission into the guided mode does not reach the strong-coupling regime for individual atoms, one can obtain high cooperativity for ensembles of a few thousand atoms due to the tight confinement of the guided modes and constructive interference over the entire chain of trapped atoms. We calculate the dyadic Green's function, which determines the scattering of light by atoms in the presence of the fiber, and thus the phase shift and polarization rotation induced on the guided light by the trapped atoms. The Green's function is related to a full Heisenberg-Langevin treatment of the dispersive response of the quantized field to tensor polarizable atoms. We apply our formalism to quantum nondemolition (QND) measurement of the atoms via polarimetry. We study shot-noise-limited detection of atom number for atoms in a completely mixed spin state and the squeezing of projection noise for atoms in clock states. Compared with squeezing of atomic ensembles in free space, we capitalize on unique features that arise in the nanofiber geometry including anisotropy of both the intensity and polarization of the guided modes. We use a first-principles stochastic master equation to model the squeezing as a function of time in the presence of decoherence due to optical pumping. We find a peak metrological squeezing of ˜5 dB is achievable with current technology for ˜2500 atoms trapped 180 nm from the surface of a nanofiber with radius a =225 nm.

  10. Analytical Investigations on Carrier Phase Recovery in Dispersion-Unmanaged n-PSK Coherent Optical Communication Systems

    Directory of Open Access Journals (Sweden)

    Tianhua Xu

    2016-09-01

    Full Text Available Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n-PSK optical fiber communication systems, involving a one-tap normalized least-mean-square (LMS algorithm, a block-wise average algorithm, and a Viterbi-Viterbi algorithm. The analytical expressions for evaluating the estimated carrier phase and for predicting the bit-error-rate (BER performance (such as the BER floors have been presented and discussed in the n-PSK coherent optical transmission systems by considering both the laser phase noise and the equalization enhanced phase noise. The results indicate that the Viterbi-Viterbi carrier phase recovery algorithm outperforms the one-tap normalized LMS and the block-wise average algorithms for small phase noise variance (or effective phase noise variance, while the one-tap normalized LMS algorithm shows a better performance than the other two algorithms for large phase noise variance (or effective phase noise variance. In addition, the one-tap normalized LMS algorithm is more sensitive to the level of modulation formats.

  11. Submersible optical sensors exposed to chemically dispersed crude oil: wave tank simulations for improved oil spill monitoring.

    Science.gov (United States)

    Conmy, Robyn N; Coble, Paula G; Farr, James; Wood, A Michelle; Lee, Kenneth; Pegau, W Scott; Walsh, Ian D; Koch, Corey R; Abercrombie, Mary I; Miles, M Scott; Lewis, Marlon R; Ryan, Scott A; Robinson, Brian J; King, Thomas L; Kelble, Christopher R; Lacoste, Jordanna

    2014-01-01

    In situ fluorometers were deployed during the Deepwater Horizon (DWH) Gulf of Mexico oil spill to track the subsea oil plume. Uncertainties regarding instrument specifications and capabilities necessitated performance testing of sensors exposed to simulated, dispersed oil plumes. Dynamic ranges of the Chelsea Technologies Group AQUAtracka, Turner Designs Cyclops, Satlantic SUNA and WET Labs, Inc. ECO, exposed to fresh and artificially weathered crude oil, were determined. Sensors were standardized against known oil volumes and total petroleum hydrocarbons and benzene-toluene-ethylbenzene-xylene measurements-both collected during spills, providing oil estimates during wave tank dilution experiments. All sensors estimated oil concentrations down to 300 ppb oil, refuting previous reports. Sensor performance results assist interpretation of DWH oil spill data and formulating future protocols.

  12. Focal construct geometry for high intensity energy dispersive x-ray diffraction based on x-ray capillary optics.

    Science.gov (United States)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi; Jiang, Bowen; Zhu, Yu

    2016-03-14

    We presented a focal construct geometry (FCG) method for high intensity energy dispersive X-ray diffraction by utilizing a home-made ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL). The ESBC was employed to focus the X-rays from a conventional laboratory source into a small focal spot and to produce an annular X-ray beam in the far-field. Additionally, diffracted polychromatic X-rays were confocally collected by the PPXRL attached to a stationary energy-resolved detector. Our FCG method based on ESBC and PPXRL had achieved relatively high intensity diffraction peaks and effectively narrowed the diffraction peak width which was helpful in improving the potential d-spacing resolution for material phase analysis.

  13. Optical activity studies of hydrogen-deuterium exchange

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, L.J.

    1990-01-01

    The potassium complexes of racemic and optically active forms of 1,2-propanediaminetriacetatoacetic acid nickel-ate (II) were prepared stoichiometrically by two different experimental procedures. The complexes were characterized by UV-VIS absorption spectroscopy, infrared spectroscopy, and thermal analysis. Circular dichroism and optical rotatory dispersion values were obtained on the optically active complexes. TGA and IR spectroscopy techniques suggest that {Delta}-K (Ni(R ({minus})HPDTA)) H{sub 2}O (1)and {Lambda}-K (Ni(S (+)HPDTA)) H{sub 2}O (2) have different configurations in solution than in the solid state. Solid complexes of (1) are theorized to have the nickel (II) ion bound pentadentate to the PDTA ligand and unidentate to a water molecule. The free carboxyl arm of the PDTA ligand is protonated. Dissolution of the complexes results in rotational changes which occur with time. The rate of rotational change has been kinetically measured, which results in three pH dependent rate constants. An isotope effect for such reactions in H{sub 2}O and D{sub 2}O has been measured. The base-catalyzed hydrogen-deuterium exchange of the out-of-plane glycinate rings of (1) and (2) complexes has been determined for three of the four glycinate protons by ORD. The rate of hydrogen-deuterium exchange is extremely slow and consecutive proton exchanges are not independent of one another over sufficiently long periods, such that measurement of {alpha}{sub {infinity}} are calculated by three differing mathematical models and applied to the calculation of the hydrogen-deuterium rate constants.

  14. Radiation-induced polymerization of {beta}(+)-pinene and synthesis of optically active {beta}(+)/{beta}(-)pinene polymers and copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Franco, E-mail: franco.cataldo@fastwebnet.i [Lupi Chemical Research, Via Casilina 1626/A, 00133 Rome (Italy); Lilla, Edo; Ursini, Ornella [Institute of Chemical Methodologies, CNR, Via Salaria Km. 29300, Monterotondo Stazione 00016, Rome (Italy)

    2011-06-15

    Poly-{beta}(+)-pinene (pB(+)p) was synthesized with {gamma} irradiation of the monomer {beta}(+)-pinene in bulk under vacuum at 1181 kGy. Also scalemic mixtures of {beta}(+)-pinene and {beta}(-)-pinene were irradiated at 1181 kGy to obtain synthetic copolymers of pB(+)/B(-)p. For comparison also {beta}(-)-pinene was converted into poly-{beta}(-)-pinene (pB(-)p) under the identical conditions adopted for its enantiomer. Furthermore pB(+)p and pB(-)p were also synthesized by thermal processing under the action of a chemical free radical initiator. The optical rotatory dispersion (ORD) of all pBp resins synthesized were accurately studied in the spectral range comprised between 375 and 625 nm and a curious asymmetry in the ORD of pB(+)p versus the ORD of pB(-)p is reported. Furthermore, it is shown that (+)-p-menth-1-ene and (-)-p-menth-1-ene are useful as a model compounds for the pBp resins and for the explanation of the amplification of the optical activity of the {beta}(+)-pinene and {beta}(-)-pinene after their ring-opening polymerization to pB(+)p and pB(-)p. The pBp resins were studied also by FT-IR spectroscopy and by thermal analysis (TGA and DTG).

  15. The influence of thermal and free carrier dispersion effects on all-optical wavelength conversion in a silicon racetrack-shaped microring resonator

    Science.gov (United States)

    Wang, Zhaolu; Liu, Hongjun; Sun, Qibing; Huang, Nan; Li, Shaopeng; Han, Jing

    2016-07-01

    We experimentally demonstrate ultra-low pump power wavelength conversion based on four-wave mixing in a silicon racetrack-shaped microring resonator. When the pump and signal are located at the resonance wavelengths, wavelength conversion with a pump power of only 1 mW can be realized in this microring resonator because of the resonant enhancement of the device. However, saturation of the conversion efficiency occurs because of the shift of the resonance peak, which is caused by the change of the effective refractive index induced by a combination of thermal and free carrier dispersion effects, and it is demonstrated that the thermal effect is the leading-order factor for the change of the refractive index. The maximum conversion efficiency of  -21 dB is obtained when the pump power is less than 12 mW. This ultra-low-power on-chip wavelength convertor based on a silicon microring resonator can find important potential applications in highly integrated optical circuits for all-optical signal processing.

  16. Optical dispersion parameters and stability of poly (9, 9‧-di-n-octylfluorenyl-2.7-diyl)/ZnO nanohybrid films: towards organic photovoltaic applications

    Science.gov (United States)

    El-Bashir, S. M.; Alenazi, W. K.; AlSalhi, M. S.

    2017-02-01

    Conjugated polymer nanohybrid films were prepared from poly (9,9‧-di-n-octylfluorenyl-2.7-diyl) (PFO) and zinc oxide (ZnO) nanoparticles. ZnO nanopowder was prepared by the solgel method, different ratios of PFO/ZnO nanohybrids have been prepared using solution blending method. Then, the blends were spin-coated onto glass substrates at 2000 rpm for 1 min. and subsequently dried at room temperature. XRD and TEM were used to determine the structural properties, while UV–Vis and photoluminescence spectrophotometers were employed to investigate the optical properties of the films. The spectral distribution of specular reflectance were used to calculate the refractive index n (λ) and the optical dispersion parameters were determined according to Wemple and Didomenico (WD) model. The effect of ZnO NPs on the direct and indirect band gap energies, photo- and thermal stability was also discussed. A significant enhancement in the light emitting properties has been observed by increasing the concentration of ZnO NPs.

  17. Integral Field Spectroscopy of High-Redshift Star Forming Galaxies with Laser Guided Adaptive Optics: Evidence for Dispersion-Dominated Kinematics

    CERN Document Server

    Law, David R; Erb, Dawn K; Larkin, James E; Pettini, Max; Shapley, Alice E; Wright, Shelley A

    2007-01-01

    We present early results from an ongoing study of the kinematic structure of star-forming galaxies at redshift z ~ 2 - 3 using integral-field spectroscopy of rest-frame optical nebular emission lines in combination with Keck laser guide star adaptive optics (LGSAO). We show kinematic maps of 3 target galaxies Q1623-BX453, Q0449-BX93, and DSF2237a-C2 located at redshifts z = 2.1820, 2.0067, and 3.3172 respectively, each of which is well-resolved with a PSF measuring approximately 0.11 - 0.15 arcsec (~ 900 - 1200 pc at z ~ 2-3) after cosmetic smoothing. Neither galaxy at z ~ 2 exhibits substantial kinematic structure on scales >~ 30 km/s; both are instead consistent with largely dispersion-dominated velocity fields with sigma ~ 80 km/s along any given line of sight into the galaxy. In contrast, DSF2237a-C2 presents a well-resolved gradient in velocity over a distance of ~ 4 kpc with peak-to-peak amplitude of 140 km/s. It is unlikely that DSF2237a-C2 represents a dynamically cold rotating disk of ionized gas as ...

  18. CT-functional diagnostics of the rotatory instability of upper cervical spine. 1. An experimental study on cadavers.

    Science.gov (United States)

    Dvorak, J; Panjabi, M; Gerber, M; Wichmann, W

    1987-04-01

    Twelve specimens of the upper cervical spine were functionally examined by using radiography, cineradiography and computerized tomographic (CT) scan. The range of rotation was measured from CT images after maximal rotations to both sides. The left alar ligament was then cut and the examination repeated. The alar and transverse ligaments could be differentiated on CT images in axial, sagittal, and coronal views. Rotation at occiput-atlas was 4.35 degrees to the right and 5.9 degrees to the left and at atlas-axis it was 31.4 degrees to the right and 33 degrees to the left. After one-sided lesion of the alar ligament, there was an overall increase of 10.8 degrees or 30% of original rotation to the opposite side, divided about equally between the occiput-atlas and the atlas-axis. It is concluded that a lesion (irreversible overstretching or rupture of alar ligaments) can result in rotatory hypermobility or instability of the upper cervical spine.

  19. An adaptive method with weight matrix as a function of the state to design the rotatory flexible system control law

    Science.gov (United States)

    Souza, Luiz C. G.; Bigot, P.

    2016-10-01

    One of the most well-known techniques of optimal control is the theory of Linear Quadratic Regulator (LQR). This method was originally applied only to linear systems but has been generalized for non-linear systems: the State Dependent Riccati Equation (SDRE) technique. One of the advantages of SDRE is that the weight matrix selection is the same as in LQR. The difference is that weights are not necessarily constant: they can be state dependent. Then, it gives an additional flexibility to design the control law. Many are applications of SDRE for simulation or real time control but generally SDRE weights are chosen constant so no advantage of this flexibility is taken. This work serves to show through simulation that state dependent weights matrix can improve SDRE control performance. The system is a non-linear flexible rotatory beam. In a brief first part SDRE theory will be explained and the non-linear model detailed. Then, influence of SDRE weight matrix associated with the state Q will be analyzed to get some insight in order to assume a state dependent law. Finally, these laws are tested and compared to constant weight matrix Q. Based on simulation results; one concludes showing the benefits of using an adaptive weight Q rather than a constant one.

  20. Pulsing frequency induced change in optical constants and dispersion energy parameters of WO{sub 3} films grown by pulsed direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Punitha, K. [Department of Physics, Alagappa University, Karaikudi 630 004 (India); Sivakumar, R., E-mail: krsivakumar1979@yahoo.com [Directorate of Distance Education, Alagappa University, Karaikudi 630 004 (India); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi 630 004 (India)

    2014-03-21

    In this work, we present the pulsing frequency induced change in the structural, optical, vibrational, and luminescence properties of tungsten oxide (WO{sub 3}) thin films deposited on microscopic glass and fluorine doped tin oxide (SnO{sub 2}:F) coated glass substrates by pulsed dc magnetron sputtering technique. The WO{sub 3} films deposited on SnO{sub 2}:F substrate belongs to monoclinic phase. The pulsing frequency has a significant influence on the preferred orientation and crystallinity of WO{sub 3} film. The maximum optical transmittance of 85% was observed for the film and the slight shift in transmission threshold towards higher wavelength region with increasing pulsing frequency revealed the systematic reduction in optical energy band gap (3.78 to 3.13 eV) of the films. The refractive index (n) of films are found to decrease (1.832 to 1.333 at 550 nm) with increasing pulsing frequency and the average value of extinction coefficient (k) is in the order of 10{sup −3}. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (E{sub d}) parameters, dielectric constants, plasma frequency, oscillator strength, and oscillator energy (E{sub o}) of WO{sub 3} films were calculated and reported for the first time due to variation in pulsing frequency during deposition by pulsed dc magnetron sputtering. The E{sub o} is change between 6.30 and 3.88 eV, while the E{sub d} varies from 25.81 to 7.88 eV, with pulsing frequency. The Raman peak observed at 1095 cm{sup −1} attributes the presence of W-O symmetric stretching vibration. The slight shift in photoluminescence band is attributed to the difference in excitons transition. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena.

  1. Perfect Dispersive Medium

    CERN Document Server

    Gupta, Shulabh

    2015-01-01

    Dispersion is at the heart of all ultrafast real-time signal processing systems across the entire electromagnetic spectrum ranging from radio-frequencies to optics. However, following Kramer-Kronig relations, these signal processing systems have been plagued with the parasitic amplitude distortions due to frequency dependent, and non-flat amplitude transmission of naturally dispersive media. This issue puts a serious limitation on the applicability and performance of these signal processing systems. To solve the above mentioned issue, a perfect dispersive medium is proposed in this work, which artificially violates the Kramer-Kronig relations, while satisfying all causality requirements. The proposed dispersive metamaterial is based on loss-gain metasurface pairs and exhibit a perfectly flat transmission response along with arbitrary dispersion in a broad bandwidth, thereby solving a seemingly unavoidable issue in all ultrafast signal processing systems. Such a metamaterial is further shown using sub-waveleng...

  2. Chromatic dispersion mitigation in long-haul fiber-optic communication networks by sub-band partitioning.

    Science.gov (United States)

    Malekiha, Mahdi; Tselniker, Igor; Plant, David V

    2015-12-14

    We propose and experimentally demonstrate a novel sub-band multiplexed data architecture for chromatic dispersion (CD) mitigation. We have demonstrated 32 GBaud multi-sub-band (MSB) dual-polarization (DP) 16QAM transmission over 2400 km. Using this approach, the transmitted signal bandwidth is divided into multiple narrow-bandwidth sub-bands, each operating at a lower baud rate. Within each sub-band bandwidth, the CD frequency response can be approximated as a linear-phase band-pass filter, which can be considered as an analog delay that does not require compensation. Therefore, the resulting receiver digital signal processing (DSP) is simplified due to the removal of the CD compensation equalizer. In addition, this leads to efficient parallelization of DSP tasks by deploying multiple independent sub-band processors running at a lower clock rate. The proposed system reduces receiver computational complexity and offers 1 dB higher Kerr-nonlinearity tolerance and 2% extended transmission reach in comparison to the conventional single carrier systems.

  3. Generation of 1.024-Tb/s Nyquist-WDM phase-conjugated twin vector waves through polarization-insensitive optical parametric amplification enabling transmission over 4000-km dispersion-managed TWRS fiber

    DEFF Research Database (Denmark)

    Liu, Xiang; Hu, Hao; Chandrasekhar, S.;

    2013-01-01

    We experimentally demonstrate the first Tb/s Nyquist-WDM phase-conjugated twin waves, consisting of eight 128-Gb/s PDM-QPSK signals and their idlers, by a broadband polarization-insensitive fiber optical parametric amplifier, enabling more than doubled reach in dispersion-managed transmission. © ...

  4. Improving the analytical performance of hydride generation non-dispersive atomic fluorescence spectrometry. Combined effect of additives and optical filters

    Science.gov (United States)

    D'Ulivo, Alessandro; Bramanti, Emilia; Lampugnani, Leonardo; Zamboni, Roberto

    2001-10-01

    The effects of tetrahydroborate and acid concentration and the presence of L-cysteine and thiourea were investigated in the determination of As, Bi and Sn using continuous flow hydride generation atomic fluorescence spectrometry (HG AFS). The aim was to find conditions allowing the control of those effects exerting negative influence on the analytical performance of the HG AFS apparatus. The effects taken into account were: (i) the radiation scattering generated by carryover of solution from the gas-liquid separator to the atomizer; (ii) the introduction of molecular species generated by tetrahydroborate decomposition into the atomizer; and (iii) interference effects arising from other elements in the sample matrix and from different acids. The effects (i) and (ii) could be controlled using mild reaction conditions in the HG stage. The effect of HG conditions on carryover was studied by radiation scattering experiments without hydride atomization. Compromised HG conditions were found by studying the effects of tetrahydroborate (0.1-20 g l -1) and acid (0.01-7 mol l -1) concentration, and the addition of L-cysteine (10 g l -1) and thiourea (0.1 mol l -1) on the HG AFS signals. The effect of optical filters was investigated with the aim of improving the signal-to-noise ratio. Optical filters with peak wavelengths of 190 and 220 nm provided an improvement of detection limits by factors of approximately 4 and 2 for As and Te, respectively. Under optimized conditions the detection limits were 6, 5, 3, 2, 2 and 9 ng l -1 for As, Sb, Bi, Sn, Se and Te, respectively. Good tolerance to various acid compositions and sample matrices was obtained by using L-cysteine or thiourea as masking agents. Determination of arsenic in sediment and copper certified reference materials, and of bismuth in steel, sediment, soil and ore certified reference material is reported.

  5. Chromatic Dispersion Estimation in Digital Coherent Receivers

    DEFF Research Database (Denmark)

    Soriano, Ruben Andres; Hauske, Fabian N.; Guerrero Gonzalez, Neil

    2011-01-01

    Polarization-diverse coherent demodulation allows to compensate large values of accumulated linear distortion by digital signal processing. In particular, in uncompensated links without optical dispersion compensation, the parameter of the residual chromatic dispersion (CD) is vital to set...

  6. 基于动态强色散控制的光保密通信系统%Optical secure communication system based on dynamic strong dispersion control

    Institute of Scientific and Technical Information of China (English)

    蔡炬; 白秋剑

    2012-01-01

    提出一种全新的基于动态强色散控制原理的光保密通信方案.首先对基于动态强色散控制的保密通信原理进行阐述,根据给出的光保密通信系统结构原理图对整个系统构成及各部分功能进行了详细分析,然后搭建了一个高速仿真系统,对其可行性和系统性能进行了验证.最后展望了该方案在保密通信领域的应用前途.%A novel solution of optical secure communication system by using dynamic strong dispersion control is proposed. Its theoretical principle and system structure are presented firstly, and then its feasibility and performance are verified by simulation.

  7. Applying the data fusion method to evaluation of the performance of two control signals in monitoring polarization mode dispersion effects in fiber optic links

    Science.gov (United States)

    Dashtbani Moghari, M.; Rezaei, P.; Habibalahi, A.

    2015-02-01

    With increasing distance and bit rate in fiber optic links the effects of polarization mode dispersion (PMD) have been highlighted. Since PMD has a statistical nature, using a control signal that can provide accurate information to dynamically tune a PMD compensator is of great importance. In this paper, we apply the data fusion method with the aim of introducing a method that can be used to evaluate more accurately the performance of control signals before applying them in a PMD compensation system. Firstly, the minimum and average degree of polarization (DOP_min and DOP_ave respectively) as control signals in monitoring differential group delay (DGD) for a system including all-order PMD are calculated. Then, features including the amounts of sensitivity and ambiguity in DGD monitoring are calculated for NRZ data format as DGD to bit time (DGD/T) varies. It is shown that each of the control signals mentioned has both positive and negative features for efficient DGD monitoring. Therefore, in order to evaluate features concurrently and increase reliability, we employ data fusion to fuse features of each control signal, which makes evaluating and predicting the performance of control signals possible, before applying them in a real PMD compensation system. Finally, the reliability of the results obtained from data fusion is tested in a typical PMD compensator.

  8. Modified Pippard relationship describing the Raman frequency shifts of the rotatory lattice mode of ammonia solid II in the vicinity of its melting point

    Indian Academy of Sciences (India)

    H Karacali; H Yurtseven

    2005-11-01

    We relate in this study the thermal expansivity, , to the Raman frequency shift (1/)( /) for the rotatory lattice (librational) mode in ammonia solid II near its melting point. We have used our calculated Raman frequencies of this mode for pressures of 3.65, 5.02 and 6.57 kbars for this crystalline system. The values of the slope, d/d, which we deduced from our spectroscopic relation, are compared with those obtained experimentally. In particular, our computed slope value for the pressure of 5.02 kbar is in very good agreement with the empirical result.

  9. INFLUENCE OF CHROMATIC DISPERSION, DISPERSION SLOPE, DISPERSION CURVATURE ON MICROWAVE GENERATION USING TWO CASCADE MODULATORS

    Directory of Open Access Journals (Sweden)

    Mandeep Singh

    2013-03-01

    Full Text Available This work presents a theoretical study of harmonic generation of microwave signals after detection of a modulated optical carrier in cascaded two electro-optic modulators. Dispersion is one of the major limiting factors for microwave generation in microwave photonics. In this paper, we analyze influence of chromatic dispersion, dispersion slope, dispersion curvature on microwave generation using two cascaded MZMs and it has been found that output intensity of photodetector reduces when dispersion term up to fifth order are added. We have used the two cascaded Mach-Zehnder Modulators for our proposed model and tried to show the dispersion effect with the help of modulation depth factor of MZM, which have been not discussed earlier.

  10. Influence of Cd-content on structural and optical dispersion characteristics of nanocrystalline Zn{sub 1−x}Cd{sub x}S (0 ⩽ x ⩽ 0.9) films

    Energy Technology Data Exchange (ETDEWEB)

    Farag, A.A.M., E-mail: alaafaragg@gamil.com [Thin Film Laboratory, Physics Department, Faculty of Education, Ain Shams University, Heliopolis, Roxy, Cairo 11757 (Egypt); Physics Department, Faculty of Science and Arts, Al-Jouf University (Saudi Arabia); Abdel Rafea, M. [Electronic Materials Department, Advanced Technology and New Material Institute, City for Scientific Research and Technology Applications, New Borg El Arab City 21934, Alexandria (Egypt); Physics Department, Faculty of Science, Imam Muhammad ibn Saud University (Saudi Arabia); Roushdy, N. [Electronic Materials Department, Advanced Technology and New Material Institute, City for Scientific Research and Technology Applications, New Borg El Arab City 21934, Alexandria (Egypt); El-Shazly, O.; El-Wahidy, E.F. [Physics Department, Faculty of Science, Alexandria University, Alexandria (Egypt)

    2015-02-05

    Highlights: • Highly uniform and good adhesion of nanocrystalline Zn{sub 1−x}Cd{sub x}S films were synthesized. • Small magnitude of optical electronegativity was calculated. • Third-order nonlinear optical susceptibility and molar polarizability were considered. - Abstract: Low cost dip coating technique was successfully used to deposit highly uniform and good adhesive nanocrystalline Zn{sub 1−x}Cd{sub x}S (0 ⩽ x ⩽ 0.9) thin films. The surface morphology and crystalline structural characteristics of Zn{sub 1−x}Cd{sub x}S were achieved by using atomic force microscopy (AFM) and transmission electron microscopy (TEM), respectively. Transmission spectra show red shifting of absorption edge as the Cd content increased. The optical constants were accurately determined by using reflectance and transmittance spectra. The effect of Cd-content on refractive index, extinction index and other optical dispersion parameters were also investigated. The dispersion of the refractive index was discussed in terms of single oscillator model. In addition, the ratio of free carrier concentration to its effective mass was estimated. The calculated value of oscillator energy E{sub o} obeys the empirical relation (E{sub o} ≈ 2 E{sub g}), obtained from single oscillator model. Small magnitude of optical electronegativity (χ{sup ∗}) for Zn{sub 1−x}Cd{sub x}S (0 ⩽ x ⩽ 0.9) thin films and relatively high refractive index can be attributed to covalent nature, in agreement with β value, obtained from dispersion energy analysis. Moreover, molar polarizability and third-order nonlinear optical susceptibility were also considered.

  11. Rotatory subluxation of the scaphoid in Kienböck's disease is not a cause of scapholunate advanced collapse (SLAC) in the wrist.

    Science.gov (United States)

    Taniguchi, Y; Tamaki, T; Honda, T; Yoshida, M

    2002-07-01

    We have examined whether the rotatory subluxation of the scaphoid which is seen in patients with advanced Kienböck's disease is associated with scapholunate advanced collapse (SLAC) wrist. We studied 16 patients (11 men, 5 women) who had stage-IV Kienböck's disease with chronic subluxation of the scaphoid. All had received conservative treatment. The mean period of affection with Kienböck's disease was 30 years (14 to 49). No wrist had SLAC. In eight patients, 24 years or more after the onset of the disease, the articular surface of the radius had been remodelled by the subluxed scaphoid with maintenance of the joint space. The wrists of six patients were considered to be excellent, nine good, and one fair according to the clinical criteria of Dornan. Our findings have shown that rotatory subluxation of the scaphoid in Kienböck's disease is not a cause of SLAC wrist and therefore that scaphotrapeziotrapezoid arthrodesis is not required for the management of these patients.

  12. The role of the anterolateral ligament in ACL insufficient and reconstructed knees on rotatory stability: A biomechanical study on human cadavers.

    Science.gov (United States)

    Tavlo, M; Eljaja, S; Jensen, J T; Siersma, V D; Krogsgaard, M R

    2016-08-01

    Studies suggest that the anterolateral ligament (ALL) is important for knee stability. The purpose was to clarify ALL's effect on rotatory and anterior-posterior stability in the anterior cruciate ligament (ACL)-insufficient and reconstructed knees and the effect of reconstruction of an insufficient ALL. Eighteen cadaveric knees were included. Stability was tested for intact (+ALL), detached (-ALL) and reconstructed (+ reALL) ALL, with ACL removed (-ACL) and reconstructed (+ACL) in six combinations. All were tested in 0, 30, 60, and 90 °C flexion. Anterior-posterior stability was measured with a rolimeter. Rotation with a torque of 8.85 Nm was measured photographically. The ALL was well defined in 78% of knees. ACL reconstruction had a significant effect on anterior-posterior stability. Detaching the ALL had a significant effect on internal rotatory stability and on anterior-posterior stability in ACL-insufficient knees. Reconstruction of ACL and ALL reestablished knee stability. The appearance of the ALL was not uniform. The ALL was an internal rotational stabilizer. Anatomical ALL reconstruction in combination with ACL reconstruction could reestablish stability. ALL reconstruction might be considered in patients with combined ACL and ALL tears, but the clinical effect should be established in a controlled clinical study.

  13. Second-Order Nonlinear Optical Susceptibilities of POLY[(HEXA-2,4-DIYNYLENE-1,6-DIOXY)DIBENZOATES] Containing Azo Chromophore Disperse Red 19 BY Electroabsorption Spectroscopy

    Science.gov (United States)

    Gómez-Sosa, Gustavo; Ogawa, Takeshi; Isoshima, Takashi; Hara, Masahiko

    The second-order nonlinear optical susceptibilities χ(2) of two isomeric polymers containing an azo dye, Disperse Red 19, were determined by the first-order electroabsorption spectroscopy (EAS), and compared with values previously obtained by SHG measurements. The para-polymer was found to have higher susceptibility than the corresponding meta-polymer. χ(2) were found to be 5-6 × 10-8 esu, which are comparable to those obtained by the Maker Fringe method.

  14. Delivering dispersion-managed soliton and Q-switched pulse in fiber laser based on graphene and nonlinear optical loop mirror

    Science.gov (United States)

    Wang, W. B.; Wang, F.; Yu, Q.; Zhang, X.; Lu, Y. X.; Gu, J.

    2016-11-01

    We propose and experimentally demonstrate a bidirectional erbium-doped fiber laser delivering dispersion-managed soliton (DMS) and Q-switched pulse based on a graphene-polyvinyl alcohol (PVA) and nonlinear optical loop mirror (NOLM) saturable absorbers (SAs). In proposed structure, the DMS is achieved in clockwise (CW) direction and Q-switched pulse is obtained in counter-clockwise (CCW) direction. By properly adjusting the intracavity attenuators (ATT) and polarizer controllers (PCs), DMS in the CW direction and Q-switched pulse in the CCW direction can be obtained, respectively or simultaneously. The DMS with full width at half maximum (FWHM) of ~480 fs, signal to noise ratio (SNR) of ~60 dB and repetition frequency about 3.907 MHz is obtained. The Q-switched pulse is established at a pump power of 180 mW with a repetition rate of ~43.5 kHz and FWHM of ~8.18 μs. When the pump power is increased to 700 mW, Q-switched pulse with a repetition rate of ~107.1 kHz and FWHM of ~2.15 μs is generated. When the two type pulses are formed simultaneously, the maximum repetition rate of Q-switched pulse is 55.8 kHz and minimum FWHM is 2.81 μs, the DMS can be formed by properly adjusting PC and ATT in this case. To the best of our knowledge, it is the first time that Q-switched pulse and DMS have been acquired respectively or simultaneously in a fiber laser.

  15. Dispersion properties of photonic crystal fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim;

    1998-01-01

    Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...... crystal fibres. The results strongly indicate that these fibres have potential applications as dispersion managing components...

  16. Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links

    Science.gov (United States)

    Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

    2017-01-01

    Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

  17. Dispersion Forces

    CERN Document Server

    Buhmann, Stefan Yoshi

    2012-01-01

    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  18. Broadband dispersion engineered microresonator on-a-chip

    CERN Document Server

    Yang, Ki Youl; Cole, Daniel C; Yi, Xu; Del'Haye, Pascal; Lee, Hansuek; Li, Jiang; Oh, Dong Yoon; Diddams, Scott A; Papp, Scott B; Vahala, Kerry J

    2015-01-01

    Control of dispersion in fibre optical waveguides is of critical importance to optical fibre communications systems and more recently for continuum generation from the ultraviolet to the mid-infrared. The wavelength at which the group velocity dispersion crosses zero can be set by varying fibre core diameter or index step. Moreover, sophisticated methods to manipulate higher-order dispersion so as shape and even flatten dispersion over wide bandwidths are possible using multi-cladding fibre. Here we introduce design and fabrication techniques that allow analogous dispersion control in chip-integrated optical microresonators, and thereby demonstrate higher-order, wide-bandwidth dispersion control over an octave of spectrum. Importantly, the fabrication method we employ for dispersion control simultaneously permits optical Q factors above 100 million, which is critical for efficient operation of nonlinear optical oscillators. Dispersion control in high Q systems has taken on greater importance in recent years w...

  19. Influence of composition on optical and dispersion parameters of thermally evaporated non-crystalline Cd{sub 50}S{sub 50−x}Se{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hassanien, A.S., E-mail: a.s.hassanien@gmail.com [Engineering Mathematics and Physics Dept., Faculty of Engineering (Shoubra), Benha University (Egypt); Physics Department, Faculty of Science and Humanities in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia); Akl, Alaa A. [Physics Department, Faculty of Science and Humanities in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia)

    2015-11-05

    Non-crystalline thin films of chalcogenide Cd{sub 50}S{sub 50−x}Se{sub x} system (30 ≤ x ≤ 50) were obtained by thermal evaporation technique onto a pre-cleaned glass substrate at a vacuum of 8.2 × 10{sup −4} Pa. The deposition rate and film thickness were kept constant at about 8 nm/s and 200 nm, respectively. Amorphous/crystalline nature and chemical composition of films have been checked using X-ray diffraction and energy dispersive X-ray spectroscopy (EDX). Optical properties of thin films were investigated and studied using the corrected transmittance, T(λ) and corrected reflectance, R(λ) measurements. Obtained data reveal that, the indirect optical energy gap (E{sub g}) was decreased from 2.21 to 1.57 eV. On the contrary, Urbach energy (band tail width), E{sub U} was found to be increased from 0.29 to 0.45 eV. This behavior is believed to be associated with the increase of Se-content instead of S-content in the thin films of Cd{sub 50}S{sub 50−x}Se{sub x} system. Chemical bond approach model, CBA was used to analyze the obtained values of E{sub g} and E{sub U}. Optical density, skin depth, extinction coefficient, refractive index and optical conductivity of chalcogenide CdSSe thin films were discussed as functions of Se-content. Using Wemple-DiDomenico single oscillator model, the refractive index dispersion and energy parameters and their dependence on Se content were studied. - Highlights: • Amorphous thin films of thickness 200 nm of Cd{sub 50}S{sub 50−x}Se{sub x} (30 ≤ x ≤ 50) have prepared. • Optical properties, indirect optical energy gap and band tail width were studied. • Chemical bond approach, CBA was used to analyze the obtained values of E{sub g} and E{sub U}. • New data of dispersion refractive index parameters were investigated and discussed.

  20. All-optical NRZ-to-RZ format conversion at 10 Gbit/s with 1-to-4 wavelength multicasting exploiting cross-phase modulation & four-wave-mixing in single dispersion-flattened highly nonlinear photonic crystal fiber

    Science.gov (United States)

    Hui, Zhan-Qiang; Zhang, Bo; Zhang, Jian-Guo

    2016-04-01

    All-optical NRZ-to-RZ format conversion with a function of wavelength multicasting is proposed in this paper, which is realized by exploiting cross-phase modulation (XPM) and four-wave-mixing (FWM) in a dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF). The designed format converter is experimentally demonstrated, for which the 1-to-4 wavelength multicasting is achieved simultaneously by filtering out two FWM idler waves and both blue-chirped and red-chirped components of the broadened NRZ spectrum induced by XPM. Moreover, the wavelength tunability and dynamic characteristics of the proposed NRZ-to-RZ format converter are also exploited using the different central wavelengths of an optical clock signal and varying the input optical power at a DF-HNL-PCF in our experiment. It is shown that the designed format converter can possess a wide range of operational wavelength over 17 nm, an optimal extinction ratio of 11.6 dB, and a Q-factor of 7.1, respectively. Since the proposed scheme uses an optical fiber-based configuration and is easy for implementation, it can be very useful for future applications in advanced fiber-optic communication networks.

  1. Dispersion Modeling.

    Science.gov (United States)

    Budiansky, Stephen

    1980-01-01

    This article discusses the need for more accurate and complete input data and field verification of the various models of air pollutant dispension. Consideration should be given to changing the form of air quality standards based on enhanced dispersion modeling techniques. (Author/RE)

  2. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil biodeg

  3. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil

  4. SIMULATION OF FORWARD AND BACKWARD WAVES EVOLUTION OF FEW-CYCLE PULSES PROPAGATING IN AN OPTICAL WAVEGUIDE WITH DISPERSION AND CUBIC NONLINEARITY OF ELECTRONIC AND ELECTRONIC-VIBRATION NATURE

    Directory of Open Access Journals (Sweden)

    L. S. Konev

    2015-09-01

    Full Text Available Numerical method for calculation of forward and backward waves of intense few-cycle laser pulses propagating in an optical waveguide with dispersion and cubic nonlinearity of electronic and electronic-vibration nature is described. Simulations made with the implemented algorithm show that accounting for Raman nonlinearity does not lead to qualitative changes in behavior of the backward wave. Speaking about quantitative changes, the increase of efficiency of energy transfer from the forward wave to the backward wave is observed. Presented method can be also used to simulate interaction of counterpropagating pulses.

  5. Dispersed Fringe Sensing Analysis - DFSA

    Science.gov (United States)

    Sigrist, Norbert; Shi, Fang; Redding, David C.; Basinger, Scott A.; Ohara, Catherine M.; Seo, Byoung-Joon; Bikkannavar, Siddarayappa A.; Spechler, Joshua A.

    2012-01-01

    Dispersed Fringe Sensing (DFS) is a technique for measuring and phasing segmented telescope mirrors using a dispersed broadband light image. DFS is capable of breaking the monochromatic light ambiguity, measuring absolute piston errors between segments of large segmented primary mirrors to tens of nanometers accuracy over a range of 100 micrometers or more. The DFSA software tool analyzes DFS images to extract DFS encoded segment piston errors, which can be used to measure piston distances between primary mirror segments of ground and space telescopes. This information is necessary to control mirror segments to establish a smooth, continuous primary figure needed to achieve high optical quality. The DFSA tool is versatile, allowing precise piston measurements from a variety of different optical configurations. DFSA technology may be used for measuring wavefront pistons from sub-apertures defined by adjacent segments (such as Keck Telescope), or from separated sub-apertures used for testing large optical systems (such as sub-aperture wavefront testing for large primary mirrors using auto-collimating flats). An experimental demonstration of the coarse-phasing technology with verification of DFSA was performed at the Keck Telescope. DFSA includes image processing, wavelength and source spectral calibration, fringe extraction line determination, dispersed fringe analysis, and wavefront piston sign determination. The code is robust against internal optical system aberrations and against spectral variations of the source. In addition to the DFSA tool, the software package contains a simple but sophisticated MATLAB model to generate dispersed fringe images of optical system configurations in order to quickly estimate the coarse phasing performance given the optical and operational design requirements. Combining MATLAB (a high-level language and interactive environment developed by MathWorks), MACOS (JPL s software package for Modeling and Analysis for Controlled Optical

  6. Simultaneous All-Optical Demultiplexing and Regeneration of a Channel from a 40 Gbit/s OTDM Signals Based on SPM and XPM in Dispersion Shifted Fiber

    DEFF Research Database (Denmark)

    Yu, Jianjun; Jeppesen, Palle

    2000-01-01

    A new method for simultaneous demultiplexing and regeneration of a channel from a 40 Gbit/s OTDM signal is proposed and experimentally verified. The method is based on self-phase and cross-phase modulation in a dispersion shifted fiber.......A new method for simultaneous demultiplexing and regeneration of a channel from a 40 Gbit/s OTDM signal is proposed and experimentally verified. The method is based on self-phase and cross-phase modulation in a dispersion shifted fiber....

  7. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr; Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C. [Institut d' Électronique, Microélectronique et Nanotechnologie, UMR-CNRS 8520, PRES Université Lille Nord de France, Cité Scientifique, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq Cedex (France); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON, UMR-CNRS 6082, ENSSAT 6, rue de Kerampont, CS 80518, 22305 Lannion Cedex (France); Mattalah, M. [Laboratoire de Microélectronique, Université Djilali Liabes, 22000 Sidi Bel Abbes (Algeria); Barkad, H. A. [Institut Universitaire Technologique Industriel, Université de Djibouti, Avenue Georges Clémenceau, BP 1904 Djibouti (Djibouti); Mortet, V. [Institute of Physics of Academy of Sciences of Czech Republic, Fyzikální ústav AV CR, v.v.i., Na Slovance 1999/2 (Czech Republic); BenMoussa, A. [Solar Terrestrial Center of Excellence, Royal Observatory of Belgium, Circular 3, B-1180 Brussels (Belgium)

    2014-04-28

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.

  8. Dispersion induced penalty for a 1xN passive interferometric optical MUX/DEMUX and its reduction using all-pass filters

    DEFF Research Database (Denmark)

    Leick, Lasse; Peucheret, Christophe

    2002-01-01

    The cascadability of 1timesN passband flattened interferometer DEMUX is investigated numerically. The passband flattening process results in detrimental dispersion induced penalty at 10 Gbit/s which can be significantly reduced with all-pass filters on the input arm...

  9. Selective and sensitive speciation analysis of Cr(VI) and Cr(III) in water samples by fiber optic-linear array detection spectrophotometry after ion pair based-surfactant assisted dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Yousefi, Seyedeh Mahboobeh; Shemirani, Farzaneh

    2013-06-15

    A simple ion pair based-surfactant assisted dispersive liquid-liquid microextraction (IP-SA-DLLME) was evaluated for extraction and preconcentration of Cr(VI) and Cr(III) in aqueous samples. In this method, which was used for the first time for chromium speciation analysis, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent. Cr(VI) ions were converted into their cationic complex with 1,5-diphenylcarbazide (DPC) and then extracted into 1-octanol dispersed in aqueous solution. Cr(III) ion also can be determined by this procedure after oxidation to Cr(VI). After extraction and phase separation, upper organic phase was transferred to a micro cell of a fiber optic-linear array detection spectrophotometry (FO-LADS). The effects of various parameters on the extraction recovery were investigated. Under the optimized conditions and preconcentration of 10 mL of sample, the enrichment factor of 159 and the detection limit of 0.05 μgL(-1) were obtained. Validation of the method was performed by spiking-recovery method and comparison of results with those obtained by ET-AAS method.

  10. Normal-dispersion microresonator Kerr frequency combs

    Directory of Open Access Journals (Sweden)

    Xue Xiaoxiao

    2016-06-01

    Full Text Available Optical microresonator-based Kerr frequency comb generation has developed into a hot research area in the past decade. Microresonator combs are promising for portable applications due to their potential for chip-level integration and low power consumption. According to the group velocity dispersion of the microresonator employed, research in this field may be classified into two categories: the anomalous dispersion regime and the normal dispersion regime. In this paper, we discuss the physics of Kerr comb generation in the normal dispersion regime and review recent experimental advances. The potential advantages and future directions of normal dispersion combs are also discussed.

  11. Transmission of 32.1 Gbit/s RZ-D8PSK over 160 km using dispersion compensation by optical phase conjugation

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Peucheret, Christophe; Schiellerup, Gert

    2009-01-01

    A 32.1 Gbit/s RZ-D8PSK modulated signal was transmitted through 160 km SSMF with optical phase conjugation after 80 km. The phase conjugation was performed by four wave mixing......A 32.1 Gbit/s RZ-D8PSK modulated signal was transmitted through 160 km SSMF with optical phase conjugation after 80 km. The phase conjugation was performed by four wave mixing...

  12. Six-wave mixing phase-dispersion by optical heterodyne detection in dressed reverse N-type four-level system

    Institute of Scientific and Technical Information of China (English)

    Gan Chen-Li; Nie Zhi-Qiang; Li Ling; Shen Lei-Jian; Zhang Yan-Peng; Song Jian-Ping; Li Yuan-Yuan; Zhang Xiang-Chen; Lu Ke-Qing

    2007-01-01

    We have investigated the dressed effects of non-degenerate four-wave mixing (NDFWM) and demonstrated a phase-sensitive method of studying the fifth-order nonlinear susceptibility due to atomic coherence in RN-type four-level system. In the presence of a strong coupling field, NDFWM spectrum exhibits Autler-Townes splitting, accompanied by either suppression or enhancement of the NDFWM signal, which is directly related to the competition between the absorption and dispersion contributions. The heterodyne-detected nonlinear absorption and dispersion of six-wave mixing signal in the RN-type system show that the hybrid radiation-matter detuning damping oscillation is in the THz range and can be controlled and modified through the colour-locked correlation of twin noisy fields.

  13. Dispersive shock waves with nonlocal nonlinearity

    CERN Document Server

    Barsi, Christopher; Sun, Can; Fleischer, Jason W

    2007-01-01

    We consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell, and results agree with a hydrodynamic theory of propagation.

  14. Dispersive shock waves with nonlocal nonlinearity.

    Science.gov (United States)

    Barsi, Christopher; Wan, Wenjie; Sun, Can; Fleischer, Jason W

    2007-10-15

    We consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell, and results agree with a hydrodynamic theory of propagation.

  15. Chromatic Dispersion Estimation in Digital Coherent Receivers

    DEFF Research Database (Denmark)

    Soriano, Ruben Andres; Hauske, Fabian N.; Guerrero Gonzalez, Neil;

    2011-01-01

    Polarization-diverse coherent demodulation allows to compensate large values of accumulated linear distortion by digital signal processing. In particular, in uncompensated links without optical dispersion compensation, the parameter of the residual chromatic dispersion (CD) is vital to set the ac...

  16. Optical Solitons

    Science.gov (United States)

    Taylor, J. R.

    2005-08-01

    1. Optical solitons in fibres: theoretical review A. Hasegawa; 2. Solitons in optical fibres: an experimental account L. F. Mollenauer; 3. All-optical long-distance soliton-based transmission systems K. Smith and L. F. Mollenauer; 4. Nonlinear propagation effects in optical fibres: numerical studies K. J. Blow and N. J. Doran; 5. Soliton-soliton interactions C. Desem and P. L. Chu; 6. Soliton amplification in erbium-doped fibre amplifiers and its application to soliton communication M. Nakazawa; 7. Nonlinear transformation of laser radiation and generation of Raman solitons in optical fibres E. M. Dianov, A. B. Grudinin, A. M. Prokhorov and V. N. Serkin; 8. Generation and compression of femtosecond solitons in optical fibers P. V. Mamyshev; 9. Optical fibre solitons in the presence of higher order dispersion and birefringence C. R. Menyuk and Ping-Kong A. Wai; 10. Dark optical solitons A. M. Weiner; 11. Soliton Raman effects J. R. Taylor; Bibliography; Index.

  17. The similarity of interactions between (3+1)D spatiotemporal optical solitons in both the dispersive medium with cubic-quintic nonlinearity and the saturable medium

    Institute of Scientific and Technical Information of China (English)

    Peng Jin-Zhang; Yang Hong; Tang Yi

    2009-01-01

    By making use of the split-step Fourier method, this paper numerically simulates dynamical behaviors, including repulsion, fusion, scattering and spiraling of colliding (3+1)D spatiotemporal solitons in both the dispersive medium with cubic-quintic and the saturable medium. Careful comparison of the colliding behaviors in these two media is presented. Although the origin of the nonlinearities is different in these two media, the obtained results show that the dynamical behaviors are very similar. This presents additional evidence to support the supposition of universality of interactions between solitons.

  18. In situ analysis of electrocrystallization process of metal electrodeposition with confocal energy dispersive X-ray diffraction based on polycapillary X-ray optics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fangzuo; Liu, Zhiguo [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi, E-mail: stx@bnu.edu.cn [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Yang, Chaolin; Sun, Weiyuan; Sun, Xuepeng [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma, Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Ding, Xunliang [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2015-06-11

    The confocal energy dispersive X-ray diffraction (EDXRD) based on a polycapillary focusing X-ray lens (PFXRL) in excitation channel and a polycapillary parallel X-ray lens (PPXRL) in detection channel was presented to study the electrocrystallization process of metal electrodeposition. The input focal spot of the PPXRL and the output focal spot of the PFXRL was adjusted in a confocal configuration, and only the X-rays from the volume overlapped by the two foci could be accordingly detected by the detector. The experimental results demonstrated the confocal EDXRD could be used to in situ real-time analysis of electrochemical crystal growth process.

  19. Mobility of the ankle joint: recording of rotatory movements in the talocrural joint in vitro with and without the lateral collateral ligaments of the ankle.

    Science.gov (United States)

    Rasmussen, O; Tovborg-Jensen, I

    1982-02-01

    A method for graphic recording of rotatory movements in osteoligamentous ankle preparations is described. By this method it is possible to record characteristic mobility patterns in two planes at the same time. The ankle is affected by a known torque, so that the individual mobility patterns are reproducible with unchanged condition of the ligaments. Six amputated legs were investigated in the sagittal and horizontal planes and another six in the sagittal and frontal planes. Mobility patterns were recorded with intact ligaments and after successive cutting of the lateral collateral ligaments of the ankle in the anteroposterior direction. In the sagittal plane increased dorsiflexion was observed after total cutting of the lateral ligaments, while plantar flexion remained unchanged. In the horizontal plane the internal rotation of the talus increased in step with increasing injury to the ligament, particularly when the ankle was plantar flexed. When all collateral ligaments had been cut, an increase in external rotation occurred, especially in dorsiflexion. In the frontal plane the talar tilt increased gradually with increasing injury to the ligaments. Talar tilt was at a maximum in the neutral position of the ankle or in plantar flexion. After total severing of the collateral ligaments, however, talar tilt was most marked in dorsiflexion of the ankle.

  20. 颈椎定点旋转手法"点"的数字化解剖%Digital anatomical position of the "point" in cervical vertebra fixed-point rotatory technique

    Institute of Scientific and Technical Information of China (English)

    袁元杏; 万磊; 李义凯; 陈静

    2011-01-01

    背景:虽然颈椎定点旋转复位手法效果显著,但其机制一直缺乏深入的研究.临床上对所要实施的推拿力和旋转节段无法做到精确控制,有时会造成手法的医源性损伤.目的:从颈椎定点旋转手法旋转中心点的角度分析旋转手法的作用途径.方法:在64排螺旋CT工作平台扫描标本,层距1 mm.在PHILIPS MEDICAL SYSTEMS图像处理功能模块中提取图片中轮廓线数据,进行上颈椎三维结构重建和图像显示.取枢椎棘突顶点(A点)、齿突垂直轴心(B点)以及两者之间连线的中点(C点)为旋转轴心(模拟中的旋转中心点),分别以各点为原点建立球坐标系.观察枢椎棘突顶点与下颌尖旋转前后的连线夹角,以及齿突垂直轴心与下颌尖旋转前后的连线夹角.结果与结论:做定点手法旋转时其中心并非是施术者利手作用的枢椎棘突顶点,而是枢椎齿突垂直轴心;实际轴心旋转角>术者观察角.提示应建立颈椎定轴旋转的新概念,并掌握颈椎定轴旋转手法的原则,以指导临床正确应用脊柱旋转类手法.%BACKGROUND: Although the fixed-point cervical vertebra rotating reduction has a notable treatment effect, yet it has not been deeply studied in the medical field. Some clinical surgeons feel difficult to make an accurate control on the power and rotatory joint position while operating, even results in iatrogenic injury. OBJECTIVE: To discuss the action mechanism of rotatory technique based on the central rotatory point of cervical vertebra fixed-point rotatory technique. METHODS: Samples were scanned through a 64-row spiral CT working platform at 1-mm layer distance. The picture's profilogram data were extracted from the image processing functional module in PHILIPS MEDICAL SYSTEMS, and then the three-dimensional structure of the upper cervical vertebra was reconstructed and displayed. Taking the axis spinous process peak (point A), odontoid process vertical axes (point B

  1. All-optical wavelength multicasting with extinction ratio enhancement using pump-modulated four-wave mixing in a dispersion-flattened nonlinear photonic crystal fiber

    DEFF Research Database (Denmark)

    Chow, K.K.; Shu, Chester; Lin, Chinlon;

    2006-01-01

    All optical wavelength multicasting at 4 x 10 Gb/s with extinction ratio enhancement has been demonstrated based on pump-modulated four-wave mixing in a nonlinear photonic crystal fiber. We show that the input signal wavelength can simultaneously convert to four different wavelengths, with a power...

  2. Substrate-mediated sub-diffraction guiding of optical signals through a linear chain of metal nanoparticles : Polarization dependence and the role of the dispersion relation

    NARCIS (Netherlands)

    Compaijen, P.J.; Malyshev, V.A.; Knoester, J.

    2013-01-01

    We theoretically investigate the efficiency of transmitting optical signals through a linear chain consisting of identical and equidistantly spaced silver nanoparticles in the presence of a reflecting substrate. The energy exchange between surface plasmon polaritons of the chain and the substrate ca

  3. Dispersion of linear and nonlinear optical susceptibilities in calcium neodymium oxyborate Ca4NdO(BO3)3-LDA versus GGA.

    Science.gov (United States)

    Reshak, Ali H; Auluck, S; Kityk, I V

    2009-02-26

    We have performed ab inito theoretical calculations of the electronic structure and the linear and nonlinear optical susceptibilities for calcium neodymium oxyborate Ca4NdO(BO3)3 using two approximations for the exchange correlation (XC) potentials, the local density approximation (LDA) and the generalized gradient approximation (GGA). Our calculations show that this compound is metallic-like, with density of states at the Fermi energy E(F), N(E(F)), of 5.95 and 10.33 states/Ry-cell or bare electronic specific heat coefficients of 1.03 and 1.79 mJ/mol-K2 for LDA and GGA, respectively. The overlap between the valence and conduction bands is strong, resulting in metallic behavior. We found that Nd-s/p/d, Ca-s/p, B-p, and O-s/p states controlled the overlapping around E(F). The effect of LDA and GGA on the band structure, density of states, and linear optical properties is very small, while for the nonlinear optical properties, it is very pronounced. Our calculations show that χ(111)(2)(ω) is the dominant component for both LDA and GGA. We find opposite signs of the contributions of the 2ω and 1ω inter/intraband to the real and imaginary parts for the dominant component throughout the wide optical frequency range.

  4. Polarized IR reflectance spectra of the monoclinic single crystal K2Ni(SO4)2.6H2O: dispersion analysis, dielectric and optical properties.

    Science.gov (United States)

    Ivanovski, Vladimir; Mayerhöfer, Thomas G; Popp, Jürgen; Petrusevski, Vladimir M

    2008-02-01

    Polarized IR reflectance spectra of K2Ni(SO4)2.6H2O single crystal (belonging to the group of Tutton salts) were recorded at near-normal incidence. From the dispersion analysis performed on the spectra recorded from the ac crystal plane, mode parameters: transversal frequency, oscillator strength, attenuation constant and the orientation of the transition moment were determined. The polarized spectrum along the b crystallographic axis was also recorded and a dispersion analysis performed. Comparison between the spectroscopically obtained transition moment directions with those obtained from the structure data for various modes is discussed. All dielectric tensor component values were obtained for the whole mid-IR frequency range. Also, the real and the imaginary parts of the complex indexes of refraction for the waves with wave vector in the direction of the b crystallographic axis and in the ac plane (when the direction of the electric vector is oriented along the b axis) were found as functions of frequency.

  5. Single-mode dispersive waves and soliton microcomb dynamics

    Science.gov (United States)

    Yi, Xu; Yang, Qi-Fan; Zhang, Xueyue; Yang, Ki Youl; Li, Xinbai; Vahala, Kerry

    2017-03-01

    Dissipative Kerr solitons are self-sustaining optical wavepackets in resonators. They use the Kerr nonlinearity to both compensate dispersion and offset optical loss. Besides providing insights into nonlinear resonator physics, they can be applied in frequency metrology, precision clocks, and spectroscopy. Like other optical solitons, the dissipative Kerr soliton can radiate power as a dispersive wave through a process that is the optical analogue of Cherenkov radiation. Dispersive waves typically consist of an ensemble of optical modes. Here, a limiting case is studied in which the dispersive wave is concentrated into a single cavity mode. In this limit, its interaction with the soliton induces hysteresis behaviour in the soliton's spectral and temporal properties. Also, an operating point of enhanced repetition-rate stability occurs through balance of dispersive-wave recoil and Raman-induced soliton-self-frequency shift. The single-mode dispersive wave can therefore provide quiet states of soliton comb operation useful in many applications.

  6. Light dispersion in space

    Science.gov (United States)

    Barbosa, L. C.

    2015-09-01

    Considering an idea of F. Arago in 1853 regarding light dispersion through the light ether in the interstellar space, this paper presents a new idea on an alternative interpretation of the cosmological red shift of the galaxies in the universe. The model is based on an analogy with the temporal material dispersion that occurs with light in the optical fiber core. Since intergalactic space is transparent, according to the model, this phenomenon is related to the gravitational potential existing in the whole space. Thus, it is possible to find a new interpretation to Hubble's constant. In space, light undergoes a dispersion process in its path, which is interpreted by a red shift equation of the type Δz = HL, since H = (d2n/dλ2 Δv Δλ), where H means the Hubble constant, n is the refractive index of the intergalactic space, Δλ is the spectral width of the extragalactic source, and Δv is the variation of the speed of light caused by the gravitational potential. We observe that this "constant" is governed by three new parameters. Light traveling the intergalactic space undergoes red shift due to this mechanism, while light amplitude decreases with time, and the wavelength always increases, thus producing the same type of behavior given by Hubble's Law. It can be demonstrated that the dark matter phenomenon is produced by the apparent speed of light of the stars on the periphery of the galaxies, without the existence of dark energy. Based on this new idea, the model of the universe is static, lacking expansion. Other phenomena may be interpreted based on this new model of the universe. We have what we call temporal gravitational dispersion of light in space produced by the variations of the speed of light, due to the presence of the gravitational potential in the whole space.

  7. Analytical characterization of Gaussian pulse propagation in semiconductor optical amplifiers with dispersion%高斯脉冲在半导体光放大器中传输的解析表征

    Institute of Scientific and Technical Information of China (English)

    贺炜; 惠战强; 吴惠民

    2012-01-01

    采用解析方法,在考虑材料损耗和色散的情况下,详细研究了无啁啾高斯脉冲和啁啾高斯脉冲在半导体光放大器中传输的物理过程,分析了强度增益、脉冲宽度和频率啁嗽与线宽增强因子、色散系数、小信号增益特征参数及初始啁啾之间的关系.结果表明:当输入变换极限的高斯脉冲时,色散会引起增益压缩,脉冲展宽和频率啁啾;同样情况下,线宽增强因子越大,脉宽加宽越明显,输出脉冲啁嗽越大,且随着线宽增强因子的增大,输出脉冲啁啾极大值向特征参数值较小的一边移动.当输入啁啾高斯脉冲时,初始脉冲啁嗽越大,增益压缩越明显,啁啾系数为正时,脉冲单纯展宽,输出啁啾随特征参数的增大而逐渐减小,啁啾系数为负时,初始啁啾与群速度色散导致的啁啾相互竞争,致使脉冲先被压缩后被展宽;脉冲最窄处对应的特征参数随线宽增强因子的增大而先增大后减小,输出啁啾随特征参数的增大而经历振荡后趋于平稳.%Analytical characterization of un-chirped Gaussian pulse and chirped Gaussian pulse propagating through a semiconductor optical amplifier (SOA) is presented under consideration of material loss and dispersion.The physical mechanism of interaction between Gaussian pulse and semiconductor material is analyzed.Energy gain,pulse width as well as frequency chirp of Gaussian pulse output from SOA are investigated.The results demonstrate that linewidth enhancement factor,dispersion coefficient and feature parameter all play important roles in deciding the output pulse characteristic.The material dispersion has no obvious impact on gain compression induced by group velocity dispersion.The pulse width is broadened under the combined effect of material dispersion and group velocity dispersion.When a chirped Gaussian pulse propagates in an SOA,the same chirp component means the same gain compression no matter the chirp is positive

  8. Infrared optical activity: electric field approaches in time domain.

    Science.gov (United States)

    Rhee, Hanju; Choi, Jun-Ho; Cho, Minhaeng

    2010-12-21

    Vibrational circular dichroism (VCD) spectroscopy provides detailed information about the absolute configurations of chiral molecules including biomolecules and synthetic drugs. This method is the infrared (IR) analogue of the more popular electronic CD spectroscopy that uses the ultraviolet and visible ranges of the electromagnetic spectrum. Because conventional electronic CD spectroscopy measures the difference in signal intensity, problems such as weak signal and low time-resolution can limit its utility. To overcome the difficulties associated with that approach, we have recently developed femtosecond IR optical activity (IOA) spectrometry, which directly measures the IOA free-induction-decay (FID), the impulsive chiroptical IR response that occurs over time. In this Account, we review the time-domain electric field measurement and calculation methods used to simultaneously characterize VCD and related vibrational optical rotatory dispersion (VORD) spectra. Although conventional methods measure the electric field intensity, this vibrational technique is based on a direct phase-and-amplitude measurement of the electric field of the chiroptical signal over time. This method uses a cross-polarization analyzer to carry out heterodyned spectral interferometry. The cross-polarization scheme enables us to selectively remove the achiral background signal, which is the dominant noise component present in differential intensity measurement techniques. Because we can detect the IOA FID signal in a phase-amplitude-sensitive manner, we can directly characterize the time-dependent electric dipole/magnetic dipole response function and the complex chiral susceptibility that contain information about the angular oscillations of charged particles. These parameters yield information about the VCD and VORD spectra. In parallel with such experimental developments, we have also calculated the IOA FID signal and the resulting VCD spectrum. These simulations use a quantum mechanical

  9. Dispersion-Enhanced Laser Gyroscope

    Science.gov (United States)

    Smith, David D.; Chang, Hongrok; Arissian, L.; Diels, J. C.

    2008-01-01

    We analyze the effect of a highly dispersive element placed inside a modulated optical cavity on the frequency and amplitude of the output modulation to determine the conditions for enhanced gyroscopic sensitivities. The element is treated as both a phase and amplitude filter, and the time-dependence of the cavity field is considered. Both atomic gases (two-level and multi-level) and optical resonators (single and coupled) are considered and compared as dispersive elements. We find that it is possible to simultaneously enhance the gyro scale factor sensitivity and suppress the dead band by using an element with anomalous dispersion that has greater loss at the carrier frequency than at the side-band frequencies, i.e., an element that simultaneously pushes and intensifies the perturbed cavity modes, e.g. a two-level absorber or an under-coupled optical resonator. The sensitivity enhancement is inversely proportional to the effective group index, becoming infinite at a group index of zero. However, the number of round trips required to reach a steady-state also becomes infinite when the group index is zero (or two). For even larger dispersions a steady-state cannot be achieved, and nonlinear dynamic effects such as bistability and periodic oscillations are predicted in the gyro response.

  10. Dispersion-enhanced laser gyroscope

    Science.gov (United States)

    Smith, David D.; Chang, Hongrok; Arissian, L.; Diels, J. C.

    2008-11-01

    We analyze the effect of a highly dispersive element placed inside a modulated optical cavity on the frequency and amplitude of the output modulation to determine the conditions for enhanced gyroscopic sensitivities. The element is treated as both a phase and amplitude filter, and the time dependence of the cavity field is considered. Both atomic gases (two level and multilevel) and optical resonators (single and coupled) are considered and compared as dispersive elements. We find that it is possible to simultaneously enhance the gyro scale factor sensitivity and suppress the dead band by using an element with anomalous dispersion that has greater loss at the carrier frequency than at the sideband frequencies, i.e., an element that simultaneously pushes and intensifies the perturbed cavity modes, e.g. a two-level absorber or an undercoupled optical resonator. The sensitivity enhancement is inversely proportional to the effective group index, becoming infinite at a group index of zero. However, the number of round trips required to reach a steady state also becomes infinite when the group index is zero (or two). For even larger dispersions a steady state cannot be achieved, and nonlinear dynamic effects such as bistability and periodic oscillations are predicted in the gyro response.

  11. EFECTOS DE LA DISPERSIÓN POR MODO DE POLARIZACIÓN (PMD EN LA PROPAGACIÓN DE PULSOS A TRAVÉS DE FIBRAS ÓPTICAS EFFECTS OF POLARIZATION MODE DISPERSION (PMD ON PROPAGATION OF OPTICAL PULSES IN OPTICAL FIBERS

    Directory of Open Access Journals (Sweden)

    Ariel Leiva L

    2007-12-01

    Full Text Available En este trabajo se revisan los conceptos fundamentales de la dispersión por modo de polarización (PMD: Polarization Mode Dispersion que ocurre en fibras ópticas. PMD produce ensanchamientos aleatorios de los pulsos ópticos transmitidos a través de una fibra óptica y su efecto es considerable para velocidades de transmisión digital iguales o superiores a 10 Gbps. Se revisa la teoría de PMD y se plantea la relevancia de caracterizar el fenómeno en transmisión por fibra óptica, concluyéndose con un método de simulación de la propagación de pulsos afectados por PMD. Este trabajo constituye un punto de partida para posteriores análisis de los efectos de PMD en sistemas de transmisión, para su compensación y mediciónThis work reviews the fundamental concepts of polarization mode dispersion (PMD occurring in optical fibers. PMD broadens optical pulses transmitted through an optical fiber at random and its effect is significant for bit rates equal or exceeding 10 Gbps. The theory of PMD and relevance of characterizing this phenomenon in optical fiber transmission is presented, concluding with a simulation model of the optical pulse propagation, subject to PMD. This provides a starting point for further analysis of the effects of PMD in transmission systems and how to measure and compensate these

  12. Synthesis, spectral, thermal, optical dispersion and dielectric properties of nanocrystalline dimer complex (PEPyr–diCd) thin films as novel organic semiconductor

    Indian Academy of Sciences (India)

    Ahmed Farouk Al-Hossainy

    2016-02-01

    Dimer complex PEPyr–diCd (5a) has been prepared by reacting CdCl$_2$·2.5H$_2$O with 1,1$'$-bis(diphenylphosphino)ethyl-6-methyl-3-(pyridin-2-yl)-1,4-dihydro-pyridazine tungsten tetracarbonyl PEPyr (4a) as bipyridine ligand. The structural properties of PEPyr–diCd complex were characterized on the basis of elemental analysis (EA), Fourier transform infrared spectra, fast atom bombardment-mass spectrometry, thermogravimetric/ differential thermal analysis, and 1H nuclear magnetic resonance spectroscopy. The crystal is orthorhombic, space group Pbca. Cd(II) metal in PEPyr–diCd organic semiconductor complex coordinated with two N of the PEPyr and three Cl$^−$ (one terminal and two bridging). The micro-structural properties of the films were studied via X-ray diffraction, and scanning electron microscopy. The as-deposited films were annealed in air for 1 h at 150, 200, and 250°C. An average transmittance >70% for PEPyr–diCd complex at higher wavelength >800 nm was observed.In UV spectrum, the transmittance increases followed by a sharp decrease at wavelength 700–750 nm within visible range. The results of the absorption coefficient were determined to find the binding energy (EB) of PEPyr–diCd organic semiconductor complex as 0.242 and 0.47 eV, respectively. Refractive index () and absorption index () of PEPyr–diCd complex were calculated. Moreover, the dispersion parameters such as dispersion energy, oscillator energy, dielectric constant, and dissipation factor were determined. The oxidation of the imino-phosphine derivatives were examined using cyclic voltammetry in methylene chloride solvent. The cyclic voltammogram of PEPyr–diCd (5a) organic semiconductor appears to have two quasi-reversible oxidations at 543 and 441 mV. The obtained results indicate that the PEPyr–diCd organic semiconductor thin film is a good candidate in optoelectronic devices based on its band gap and dispersion parameters.

  13. Soliton trapping of dispersive waves in photonic crystal fiber with two zero dispersive wavelengths.

    Science.gov (United States)

    Wang, Weibin; Yang, Hua; Tang, Pinghua; Zhao, Chujun; Gao, Jing

    2013-05-06

    Based on the generalized nonlinear Schrödinger equation, we present a numerical study of trapping of dispersive waves by solitons during supercontinuum generation in photonic crystal fibers pumped with femtosecond pulses in the anomalous dispersion region. Numerical simulation results show that the generated supercontinuum is bounded by two branches of dispersive waves, namely blue-shifted dispersive waves (B-DWs) and red-shifted dispersive waves (R-DWs). We find a novel phenomenon that not only B-DWs but also R-DWs can be trapped by solitons across the zero-dispersion wavelength when the group-velocity matching between the soliton and the dispersive wave is satisfied, which may led to the generation of new spectral components via mixing of solitons and dispersive waves. Mixing of solitons with dispersive waves has been shown to play an important role in shaping not only the edge of the supercontinuum, but also its central part around the higher zero-dispersion wavelength. Further, we show that the phenomenon of soliton trapping of dispersive waves in photonic crystal fibers with two zero-dispersion wavelengths has a very close relationship with pumping power and the interval between two zero-dispersion wavelengths. In order to clearly display the evolution of soliton trapping of dispersive waves, the spectrogram of output pulses is observed using cross-correlation frequency-resolved optical gating technique (XFROG).

  14. Resonant-state expansion for a simple dispersive medium

    CERN Document Server

    Doost, M B; Muljarov, E A

    2015-01-01

    The resonant-state expansion (RSE), a rigorous perturbative method developed in electrodynamics for non-dispersive optical systems is applied to media with an Ohm's law dispersion, in which the frequency dependent part of the permittivity scales inversely with the frequency, corresponding to a frequency-independent conductivity. This dispersion has only a single pole at zero frequency, which is already present in the non-dispersive RSE, allowing to maintain not only the linearity of the eigenvalue problem of the RSE but also its size. Media which can be described by this dispersion over the relevant frequency range, such as optical glass or doped semiconductors, can be treated in the RSE without additional complexity. Results are presented using analytically solvable homogeneous spheres, for doped silicon and BK7 glass, both for a perturbation of the system going from non-dispersive to dispersive media and the reverse, from dispersive to non-dispersive media.

  15. Optical smoothing of laser imprinting in planar-target experiments on OMEGA EP using multi-FM 1-D smoothing by spectral dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Hohenberger, M., E-mail: mhoh@lle.rochester.edu; Shvydky, A.; Marozas, J. A.; Bonino, M. J.; Canning, D.; Collins, T. J. B.; Dorrer, C.; Kessler, T. J.; Kruschwitz, B. E.; McKenty, P. W.; Regan, S. P.; Sangster, T. C.; Zuegel, J. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road Rochester, Rochester, New York 14623 (United States); Fiksel, G. [Nuclear Engineering and Radiological Sciences (NERS), University of Michigan, Ann Arbor, Michigan 48109 (United States); Meyerhofer, D. D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-09-15

    Direct-drive ignition on the National Ignition Facility (NIF) requires single-beam smoothing to minimize imprinting of laser nonuniformities that can negatively affect implosion performance. One-dimensional, multi-FM smoothing by spectral dispersion (SSD) has been proposed to provide the required smoothing [Marozas et al., Bull. Am. Phys. Soc. 55, 294 (2010)]. A prototype multi-FM SSD system has been integrated into the NIF-like beamline of the OMEGA EP Laser System. Experiments have been performed to verify the smoothing performance by measuring Rayleigh–Taylor growth rates in planar targets of laser-imprinted and preimposed surface modulations. Multi-FM 1-D SSD has been observed to reduce imprint levels by ∼50% compared to the nominal OMEGA EP SSD system. The experimental results are in agreement with 2-D DRACO simulations using realistic, time-dependent far-field spot-intensity calculations that emulate the effect of SSD.

  16. Optical smoothing of laser imprinting in planar-target experiments on OMEGA EP using multi-FM 1-D smoothing by spectral dispersion

    Science.gov (United States)

    Hohenberger, M.; Shvydky, A.; Marozas, J. A.; Fiksel, G.; Bonino, M. J.; Canning, D.; Collins, T. J. B.; Dorrer, C.; Kessler, T. J.; Kruschwitz, B. E.; McKenty, P. W.; Meyerhofer, D. D.; Regan, S. P.; Sangster, T. C.; Zuegel, J. D.

    2016-09-01

    Direct-drive ignition on the National Ignition Facility (NIF) requires single-beam smoothing to minimize imprinting of laser nonuniformities that can negatively affect implosion performance. One-dimensional, multi-FM smoothing by spectral dispersion (SSD) has been proposed to provide the required smoothing [Marozas et al., Bull. Am. Phys. Soc. 55, 294 (2010)]. A prototype multi-FM SSD system has been integrated into the NIF-like beamline of the OMEGA EP Laser System. Experiments have been performed to verify the smoothing performance by measuring Rayleigh-Taylor growth rates in planar targets of laser-imprinted and preimposed surface modulations. Multi-FM 1-D SSD has been observed to reduce imprint levels by ˜50% compared to the nominal OMEGA EP SSD system. The experimental results are in agreement with 2-D DRACO simulations using realistic, time-dependent far-field spot-intensity calculations that emulate the effect of SSD.

  17. Dispersed Indeterminacy

    CERN Document Server

    Fayngold, Moses

    2013-01-01

    A state of a single particle can be represented by a quantum blob in the corresponding phase space, or a patch (granule) in its 2-D subspace. Its area is frequently stated to be no less than, implying that such a granule is an indivisible quantum of the 2-D phase space. But this is generally not true, as is evident, for instance, from representation of some states in the basis of innately discrete observables like angular momentum. Here we consider some dispersed states involving the evanescent waves different from that in the total internal reflection. Such states are represented by a set of separated granules with individual areas, but with the total indeterminacy . An idealized model has a discrete Wigner function and is described by a superposition of eigenstates with eigenvalues and forming an infinite periodic array of dots on the phase plane. The question about the total indeterminacy in such state is discussed. We argue that the eigenstates corresponding to the considered EW cannot be singled out by a...

  18. Optical signatures of molecular dissymmetry: combining theory with experiments to address stereochemical puzzles.

    Science.gov (United States)

    Mukhopadhyay, Parag; Wipf, Peter; Beratan, David N

    2009-06-16

    Modern chemistry emerged from the quest to describe the three-dimensional structure of molecules: van't Hoff's tetravalent carbon placed symmetry and dissymmetry at the heart of chemistry. In this Account, we explore how modern theory, synthesis, and spectroscopy can be used in concert to elucidate the symmetry and dissymmetry of molecules and their assemblies. Chiroptical spectroscopy, including optical rotatory dispersion (ORD), electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and Raman optical activity (ROA), measures the response of dissymmetric structures to electromagnetic radiation. This response can in turn reveal the arrangement of atoms in space, but deciphering the molecular information encoded in chiroptical spectra requires an effective theoretical approach. Although important correlations between ECD and molecular stereochemistry have existed for some time, a battery of accurate new theoretical methods that link a much wider range of chiroptical spectroscopies to structure have emerged over the past decade. The promise of this field is considerable: theory and spectroscopy can assist in assigning the relative and absolute configurations of complex products, revealing the structure of noncovalent aggregates, defining metrics for molecular diversity based on polarization response, and designing chirally imprinted nanomaterials. The physical organic chemistry of chirality is fascinating in its own right: defining atomic and group contributions to optical rotation (OR) is now possible. Although the common expectation is that chiroptical response is determined solely by a chiral solute's electronic structure in a given environment, chiral imprinting effects on the surrounding medium and molecular assembly can, in fact, dominate the chiroptical signatures. The theoretical interpretation of chiroptical markers is challenging because the optical properties are subtle, resulting from the strong electric dipole and the weaker electric

  19. Thermoelectric, band structure, chemical bonding and dispersion of optical constants of new metal chalcogenides Ba{sub 4}CuGa{sub 5}Q{sub 12} (Q=S, Se)

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H. [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Azam, Sikander, E-mail: sikander.physicst@gmail.com [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)

    2014-08-01

    The electronic structure and dispersion of optical constants of the Ba{sub 4}CuGa{sub 5}S{sub 12} and Ba{sub 4}CuGa{sub 5}Se{sub 12} compounds were calculated by the first-principles full-potential linearized augmented plane wave (FPLAPW) method. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel–Vosko GGA (EVGGA) to calculate the electronic structures, Fermi surface, thermoelectric, chemical bonding and dispersion of optical constants of these compounds. By investigating the influence of replacing S by Se, it has been found that the charge density around ‘Ga’ is greater in Ba{sub 4}CuGa{sub 5}Se{sub 12} than Ba{sub 4}CuGa{sub 5}S{sub 12}. Fermi surface of Ba{sub 4}CuGa{sub 5}S{sub 12} consists of an electronic sheet only because there is no empty region while Ba{sub 4}CuGa{sub 5}Se{sub 12} contains both holes and electronic sheets because this compound contains both empty and shaded region. As we replace S by Se the heights of the peaks decreases as a results the reflectivity also decreases. It is noticed that the reflectivity is over 68% (60%) for Ba{sub 4}CuGa{sub 5}S{sub 12} (Ba{sub 4}CuGa{sub 5}Se{sub 12}) compounds within the energy range studied. This implies that the material will serve as a good reflector. By replacing S by Se the figure of merit values increases from 0.97 to 1.0, which shows the good thermoelectric behavior of both compounds. - Highlights: • DFT-FPLAPW method used for calculating the properties. • For predicting the chemical bonding the charge density behavior is studied in 2D. • The optical properties were also calculated and analyzed. • The Fermi surface is composed of two bands crossing along the EF level. • The thermoelectric properties have also been calculated.

  20. Spatial and optical parameters of contrails in the vortex and dispersion regime determined by means of a ground-based scanning lidar

    Energy Technology Data Exchange (ETDEWEB)

    Freudenthaler, V.; Homburg, F.; Jaeger, H. [Fraunhofer-Inst. fuer Atmosphaerische Umweltforschung (IFU), Garmisch-Partenkirchen (Germany)

    1997-12-31

    The spatial growth of individual condensation trails (contrails) of commercial aircrafts in the time range from 15 s to 60 min behind the aircraft is investigated by means of a ground-based scanning backscatter lidar. The growth in width is mainly governed by wind shear and varies between 18 m/min and 140 m/min. The growth of the cross-section varies between 3500 m{sup 2}/min and 25000 m{sup 2}/min. These values are in agreement with results of model calculations and former field measurements. The vertical growth is often limited by boundaries of the humid layer at flight level, but values up to 18 m/min were observed. Optical parameters like depolarization, optical depth and lidar ratio, i.e. the extinction-to-backscatter ratio, have been retrieved from the measurements at a wavelength of 532 nm. The linear depolarization rises from values as low as 0.06 for a young contrail (10 s old) to values around 0.5, typical for aged contrails. The latter indicates the transition from non-crystalline to crystalline particles in persistent contrails within a few minutes. The scatter of depolarization values measured in individual contrails is narrow, independent of the contrails age, and suggests a rather uniform growth of the particles inside a contrail. (author) 18 refs.

  1. Fabrication and photophysical studies of CdTe quantum-dots dispersed in SiO2 sonogel optical-glasses

    Directory of Open Access Journals (Sweden)

    Omar G. Morales-Saavedra

    2015-12-01

    Full Text Available The catalyst-free sonogel route has been implemented to fabricate highly pure SiO2 glasses as host materials for CdTe quantum dot nanocrystals synthesized in aqueous solution. Developed CdTe-based inorganic–inorganic hybrid composites exhibited rigid bulk structures with controllable geometrical shapes and dopant concentrations, allowing the control of the optical properties in the solid-state confinement. Comprehensive linear and nonlinear photophysical characterizations were performed according to UV–vis absorbance, Raman and photoluminescent spectroscopies; the linear refractive indices of highly/lowly CdTe-doped samples were also estimated according to the Brewster angle technique. Since the hybrid glasses are amorphous in nature, the cubic nonlinear optical activity of these composites has been tested via the Z-Scan technique. Results show that the CdTe quantum dots were homogeneously embedded within the SiO2-sonogel matrix with only small guest–host molecular interactions and preserving their strong photoluminescent properties; thus providing advanced solid-state heterostructured nanocomposite materials suitable for current technological photonic applications.

  2. Dispersible crystalline nanobundles of YPO{sub 4} and Ln (Eu, Tb)-doped YPO{sub 4}: rapid synthesis, optical properties and bio-probe applications

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Shafquat, E-mail: shafquatmajeed@gmail.com [Indian Institute of Science, Materials Research Centre (India); Bashir, Mohsin [Indian Institute of Science, Department of Molecular Reproduction, Development and Genetics (MRDG) (India); Shivashankar, S. A. [Indian Institute of Science, Materials Research Centre (India)

    2015-07-15

    Undoped and Ln{sup 3+} (Eu and Tb)-doped crystalline nanobundles of YPO{sub 4} were prepared by a facile microwave-assisted route with water as a solvent and without using any surfactant. TEM investigations reveal that the as-prepared powder consists of lenticular-shaped nanobundles (∼100 nm in diameter) made of very small nanorods with diameter less than 10 nm and length varying from 20 to 50 nm. Each nanorod in turn is single crystalline, as revealed by HRTEM imaging. The as-prepared nanobundles are easily dispersible in various solvents, especially water, without any surface functionalization, which is critical for various bio-probe applications like cell and tissue imaging. The Eu- and Tb-doped YPO{sub 4} nanobundles show good photoluminescence properties and were further evaluated for their use as fluorescent biolabels. Our results show that HeLa cells labelled with Eu- and Tb-doped YPO{sub 4} nanobundles show bright red (Eu) and green (Tb) intracellular luminescence under a confocal microscope. Concentration- and time-dependent MTT cell viability assays show that the nanobundles show low toxicity towards cells which makes them promising in bioimaging field.

  3. Magerl technique for children atlantoaxial rotatory subluxation%Magerl技术治疗儿童寰枢关节旋转半脱位

    Institute of Scientific and Technical Information of China (English)

    唐明星; 张宏其; 刘金洋; 王昱翔; 郭超峰; 刘少华; 邓盎; 高琪乐; 王龙杰

    2016-01-01

    Objective To discuss the feasibility and prognosis of magerl technique for children.Atlantoaxial Rotatory Subluxation.Methods 63 patients with Atlantoaxial Rotatory Subluxation were treated in our hospital,and 16 of whom were treated with bilateral C1,2 posterior transarticular screw fixation and fusion.All cases aged from 8 to 14,with an average age of 11±2.3 years old.According to Fielding classification,10 cases were in type II,and 6 in type Ⅲ.1 patient showed dizziness,11 patients showed obvious appearance of deviation of head and neck;14 patients showed varying degrees of occipito-cervical pain,and one patient showed incomplete paralysis.All patients had undergone Halo traction,then the Magerl surgery for atlantoaxial fixation fusion.Through follow-up and photograph of atlantoaxial mouth opening,lateral cervical X-ray and atlantoaxial 3D CT,the screw position and bone graft fusion were evaluated.The clinical and radiological outcomes were evaluated according to the Symon and Lavender clinical standard,the imaging index space available for the cord (SAC),and the atlas-dens interval (ADI).Results All cases were followed up for 3 to 98 months (mean 38±14.6 months).All patients had completed the bilateral UCSS screw fixation,and the symptoms were improved significantly,without neurological symptoms aggravated or complications such as neurovascular injury.All UCSS screw position through the atlantoaxial joint was accurate,without atlanto occipital joint activity limitation.All patients got bony fusion 3 to 6 months post-operation.The clinical recovery rate was 93.8%.The SAC of C1,2 segment increased by 6.06± 1.29 mm postoperatively,which showed a significant difference compared with preoperative SAC.The SAC at the latest follow-up was 15.31±0.79 mm,showing no significant difference compared with that just postoperatively.The ADI at one month postoperatively decreased by 5.75 ± 1.53 mm,showing a significant difference compared with preoperative SAC.The ADI

  4. Seed dispersal in fens

    NARCIS (Netherlands)

    Middleton, Beth; van Diggelen, Rudy; Jensen, Kai

    2006-01-01

    Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and

  5. Minimal dispersion refractive index profiles.

    Science.gov (United States)

    Feit, M D

    1979-09-01

    The analogy between optics and quantum mechanics is exploited by considering a 2-D quantum system whose Schroedinger equation is closely related to the wave equation for light propagation in an optical fiber. From this viewpoint, Marcatili's condition for minimal-dispersion-refractive-index profiles, and the Olshansky- Keck formula for rms pulse spreading in an alpha-profile fiber may be derived without recourse to the WKB approximation. Besides affording physical insight into these results, the present approach points out a possible limitation in their application to real fibers.

  6. Single-mode dispersive waves and soliton microcomb dynamics

    CERN Document Server

    Yi, Xu; Zhang, Xueyue; Yang, Ki Youl; Vahala, Kerry

    2016-01-01

    Dissipative Kerr solitons are self-sustaining optical wavepackets in resonators. They use the Kerr nonlinearity to both compensate dispersion and to offset optical loss. Besides providing insights into nonlinear resonator physics, they can be applied in frequency metrology, precision clocks, and spectroscopy. Like other optical solitons, the dissipative Kerr soliton can radiate power in the form of a dispersive wave through a process that is the optical analogue of Cherenkov radiation. Dispersive waves typically consist of an ensemble of optical modes. A limiting case is demonstrated in which the dispersive wave is concentrated into a single cavity mode. In this limit, its interaction with the soliton is shown to induce bistable behavior in the spectral and temporal properties of the soliton. Also, an operating point of enhanced repetition-rate stability is predicted and observed. The single-mode dispersive wave can therefore provide quiet states of soliton comb operation useful in many applications.

  7. Ring-laser gyroscope system using dispersive element(s)

    Science.gov (United States)

    Smith, David D. (Inventor)

    2010-01-01

    A ring-laser gyroscope system includes a ring-laser gyroscope (RLG) and at least one dispersive element optically coupled to the RLG's ring-shaped optical path. Each dispersive element has a resonant frequency that is approximately equal to the RLG's lasing frequency. A group index of refraction defined collectively by the dispersive element(s) has (i) a real portion that is greater than zero and less than one, and (ii) an imaginary portion that is less than zero.

  8. Broadband Kerr frequency combs and intracavity soliton dynamics influenced by high-order cavity dispersion

    DEFF Research Database (Denmark)

    Wang, Shaofei; Guo, Hairun; Bai, Xuekun

    2014-01-01

    , showing that temporal shifts of steady-state intracavity solitons are induced by high-odd-order dispersion rather than high-even-order dispersion. The role of HOD on comb spectral envelopes is also elucidated through analyzing the intracavity dispersive wave generations. We further demonstrate...... that the spectral envelope of a broadband optical frequency comb can be engineered by using a cavity dispersion profile with multiple zero dispersion wavelengths. © 2014 Optical Society of America....

  9. Effect of concentration of dispersed organic matter on optical maturity parameters: Interlaboratory results of the organic matter concentration working group of the ICCP.

    Science.gov (United States)

    Mendonca, Filho J.G.; Araujo, C.V.; Borrego, A.G.; Cook, A.; Flores, D.; Hackley, P.; Hower, J.C.; Kern, M.L.; Kommeren, K.; Kus, J.; Mastalerz, Maria; Mendonca, J.O.; Menezes, T.R.; Newman, J.; Ranasinghe, P.; Souza, I.V.A.F.; Suarez-Ruiz, I.; Ujiie, Y.

    2010-01-01

    The main objective of this work was to study the effect of the kerogen isolation procedures on maturity parameters of organic matter using optical microscopes. This work represents the results of the Organic Matter Concentration Working Group (OMCWG) of the International Committee for Coal and Organic Petrology (ICCP) during the years 2008 and 2009. Four samples have been analysed covering a range of maturity (low and moderate) and terrestrial and marine geological settings. The analyses comprise random vitrinite reflectance measured on both kerogen concentrate and whole rock mounts and fluorescence spectra taken on alginite. Eighteen participants from twelve laboratories from all over the world performed the analyses. Samples of continental settings contained enough vitrinite for participants to record around 50 measurements whereas fewer readings were taken on samples from marine setting. The scatter of results was also larger in the samples of marine origin. Similar vitrinite reflectance values were in general recorded in the whole rock and in the kerogen concentrate. The small deviations of the trend cannot be attributed to the acid treatment involved in kerogen isolation but to reasons related to components identification or to the difficulty to achieve a good polish of samples with high mineral matter content. In samples difficult to polish, vitrinite reflectance was measured on whole rock tended to be lower. The presence or absence of rock fabric affected the selection of the vitrinite population for measurement and this also had an influence in the average value reported and in the scatter of the results. Slightly lower standard deviations were reported for the analyses run on kerogen concentrates. Considering the spectral fluorescence results, it was observed that the ??max presents a shift to higher wavelengths in the kerogen concentrate sample in comparison to the whole-rock sample, thus revealing an influence of preparation methods (acid treatment) on

  10. Two-Photon Polarization Dependent Spectroscopy in Chirality: A Novel Experimental-Theoretical Approach to Study Optically Active Systems

    Directory of Open Access Journals (Sweden)

    Florencio E. Hernández

    2011-04-01

    Full Text Available Many phenomena, including life itself and its biochemical foundations are fundamentally rooted in chirality. Combinatorial methodologies for catalyst discovery and optimization remain an invaluable tool for gaining access to enantiomerically pure compounds in the development of pharmaceuticals, agrochemicals, and flavors. Some exotic metamaterials exhibiting negative refractive index at optical frequencies are based on chiral structures. Chiroptical activity is commonly quantified in terms of circular dichroism (CD and optical rotatory dispersion (ORD. However, the linear nature of these effects limits their application in the far and near-UV region in highly absorbing and scattering biological systems. In order to surmount this barrier, in recent years we made important advancements on a novel non linear, low-scatter, long-wavelength CD approach called two-photon absorption circular dichroism (TPACD. Herein we present a descriptive analysis of the optics principles behind the experimental measurement of TPACD, i.e., the double L-scan technique, and its significance using pulsed lasers. We also make an instructive examination and discuss the reliability of our theoretical-computational approach, which uses modern analytical response theory, within a Time-Dependent Density Functional Theory (TD-DFT approach. In order to illustrate the potential of this novel spectroscopic tool, we first present the experimental and theoretical results obtained in C2-symmetric, axially chiral R-(+-1,1'-bi(2-naphthol, R-BINOL, a molecule studied at the beginning of our investigation in this field. Next, we reveal some preliminary results obtained for (R-3,3′-diphenyl-2,2′-bi-1-naphthol, R-VANOL, and (R-2,2′-diphenyl-3,3′-(4-biphenanthrol, R-VAPOL. This family of optically active compounds has been proven to be a suitable model for the structure-property relationship study of TPACD, because its members are highly conjugated yet photo-stable, and easily

  11. Two-photon polarization dependent spectroscopy in chirality: a novel experimental-theoretical approach to study optically active systems.

    Science.gov (United States)

    Hernández, Florencio E; Rizzo, Antonio

    2011-04-18

    Many phenomena, including life itself and its biochemical foundations are fundamentally rooted in chirality. Combinatorial methodologies for catalyst discovery and optimization remain an invaluable tool for gaining access to enantiomerically pure compounds in the development of pharmaceuticals, agrochemicals, and flavors. Some exotic metamaterials exhibiting negative refractive index at optical frequencies are based on chiral structures. Chiroptical activity is commonly quantified in terms of circular dichroism (CD) and optical rotatory dispersion (ORD). However, the linear nature of these effects limits their application in the far and near-UV region in highly absorbing and scattering biological systems. In order to surmount this barrier, in recent years we made important advancements on a novel non linear, low-scatter, long-wavelength CD approach called two-photon absorption circular dichroism (TPACD). Herein we present a descriptive analysis of the optics principles behind the experimental measurement of TPACD, i.e., the double L-scan technique, and its significance using pulsed lasers. We also make an instructive examination and discuss the reliability of our theoretical-computational approach, which uses modern analytical response theory, within a Time-Dependent Density Functional Theory (TD-DFT) approach. In order to illustrate the potential of this novel spectroscopic tool, we first present the experimental and theoretical results obtained in C(2)-symmetric, axially chiral R-(+)-1,1'-bi(2-naphthol), R-BINOL, a molecule studied at the beginning of our investigation in this field. Next, we reveal some preliminary results obtained for (R)-3,3'-diphenyl-2,2'-bi-1-naphthol, R-VANOL, and (R)-2,2'-diphenyl-3,3'-(4-biphenanthrol), R-VAPOL. This family of optically active compounds has been proven to be a suitable model for the structure-property relationship study of TPACD, because its members are highly conjugated yet photo-stable, and easily derivatized at the 5

  12. CODEX optics

    Science.gov (United States)

    Delabre, Bernard; Manescau, Antonio

    2010-07-01

    CODEX is a high resolution spectrograph for the ESO E-ELT. A classical spectrograph can only achieve a resolution of about 120.000 on a 42 m telescope with extremely large echelle gratings and cameras. This paper describes in detail the optical concept of CODEX, which uses only optical elements size similar to those in current high resolution spectrographs. This design is based on slicers, anamorphic beams and slanted VPHG as cross dispersers. In this new version of the CODEX design, no special expensive materials as calcium fluoride or abnormal dispersion glasses are needed. The optical quality is excellent and compatible with 10K x 10K detectors with 10 μm pixels.

  13. Broadband dispersion-engineered microresonator on a chip

    Science.gov (United States)

    Yang, Ki Youl; Beha, Katja; Cole, Daniel C.; Yi, Xu; Del'Haye, Pascal; Lee, Hansuek; Li, Jiang; Oh, Dong Yoon; Diddams, Scott A.; Papp, Scott B.; Vahala, Kerry J.

    2016-05-01

    The control of dispersion in fibre optical waveguides is of critical importance to optical fibre communications systems and more recently for continuum generation from the ultraviolet to the mid-infrared. The wavelength at which the group velocity dispersion crosses zero can be set by varying the fibre core diameter or index step. Moreover, sophisticated methods to manipulate higher-order dispersion so as to shape and even flatten the dispersion over wide bandwidths are possible using multi-cladding fibres. Here we introduce design and fabrication techniques that allow analogous dispersion control in chip-integrated optical microresonators, and thereby demonstrate higher-order, wide-bandwidth dispersion control over an octave of spectrum. Importantly, the fabrication method we employ for dispersion control simultaneously permits optical Q factors above 100 million, which is critical for the efficient operation of nonlinear optical oscillators. Dispersion control in high-Q systems has become of great importance in recent years with increased interest in chip-integrable optical frequency combs.

  14. Shock waves in dispersive Eulerian fluids

    CERN Document Server

    Hoefer, M A

    2013-01-01

    The long time behavior of an initial step resulting in a dispersive shock wave (DSW) for the one-dimensional isentropic Euler equations regularized by generic, third order dispersion is considered by use of Whitham averaging. Under modest assumptions, the jump conditions (DSW locus and speeds) for admissible, weak DSWs are characterized and found to depend only upon the sign of dispersion (convex or concave) and a general pressure law. Two mechanisms leading to the breakdown of this simple wave DSW theory for sufficiently large jumps are identified: a change in the sign of dispersion, leading to gradient catastrophe in the modulation equations, and the loss of genuine nonlinearity in the modulation equations. Large amplitude DSWs are constructed for several particular dispersive fluids with differing pressure laws modeled by the generalized nonlinear Schr\\"{o}dinger equation. These include superfluids (Bose-Einstein condensates and ultracold Fermions) and "optical fluids". Estimates of breaking times for smoo...

  15. Physical models of polarization mode dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Menyuk, C.R.; Wai, P.K.A. [Univ. of Maryland, Baltimore, MD (United States)

    1995-12-31

    The effect of randomly varying birefringence on light propagation in optical fibers is studied theoretically in the parameter regime that will be used for long-distance communications. In this regime, the birefringence is large and varies very rapidly in comparison to the nonlinear and dispersive scale lengths. We determine the polarization mode dispersion, and we show that physically realistic models yield the same result for polarization mode dispersion as earlier heuristic models that were introduced by Poole. We also prove an ergodic theorem.

  16. Optical gyrotropy from axion electrodynamics in momentum space.

    Science.gov (United States)

    Zhong, Shudan; Orenstein, Joseph; Moore, Joel E

    2015-09-11

    Several emergent phenomena and phases in solids arise from configurations of the electronic Berry phase in momentum space that are similar to gauge field configurations in real space such as magnetic monopoles. We show that the momentum-space analogue of the "axion electrodynamics" term E·B plays a fundamental role in a unified theory of Berry-phase contributions to optical gyrotropy in time-reversal invariant materials and the chiral magnetic effect. The Berry-phase mechanism predicts that the rotatory power along the optic axes of a crystal must sum to zero, a constraint beyond that stipulated by point-group symmetry, but observed to high accuracy in classic experimental observations on alpha quartz. Furthermore, the Berry mechanism provides a microscopic basis for the surface conductance at the interface between gyrotropic and nongyrotropic media.

  17. Optics for dummies

    CERN Document Server

    Duree, Galen C

    2011-01-01

    The easy way to shed light on Optics In general terms, optics is the science of light. More specifically, optics is a branch of physics that describes the behavior and properties of light?including visible, infrared, and ultraviolet?and the interaction of light with matter. Optics For Dummies gives you an approachable introduction to optical science, methods, and applications. You'll get plain-English explanations of the nature of light and optical effects; reflection, refraction, and diffraction; color dispersion; optical devices, industrial, medical, and military applicatio

  18. Combination of solid phase extraction and dispersive liquid–liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Shayessteh, E-mail: sdadfarnia@yazd.ac.ir; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

    2013-12-15

    Graphical abstract: Pass the sample through the basic alumina column ⇒ elute retained uranium along with the cations ⇒ convert the uranium to its anionic benzoate complex ⇒ extract its ion pair with malachite green into small volume of chloroform by DLLME ⇒ measure its absorption at 621 nm using fiber optic-linear array detection spectrophotometry. -- Highlights: • By combination of SPE and DDLME a high preconcentration factor of 2500 was obtained. • Development of SPE-DDLME-Spectrophotometric method for det. of trace amounts of uranium. • Ultra trace amount of uranium in water samples was det. by the proposed method. • The detection limit of the proposed method is comparable to the most sensitive method. • The proposed method is a free interference spectrophotometric method for uranium det. -- Abstract: A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid–liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L{sup −1}) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid–liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L{sup −1}, and a relative standard deviation of 4.1% (n = 6) at 400 ng L{sup −1} were obtained. The

  19. Stability Study of Nano-Silver Particles Dispersed in Various Solvents by Turbiscan Lab Optical Analyzer%Turbiscan多重光散射法研究纳米银溶胶的分散稳定性

    Institute of Scientific and Technical Information of China (English)

    夏朝辉; 吕丽云; 王虹

    2015-01-01

    Nano‐silver particles were synthesized through chemical reduction method ,using silver nitrate ,m‐dihydroxybenzene and polyvinylpyrrolidone as silver source ,reduction agent and protective agent respectively ;and redundant reactants were re‐moved through centrifugation and washing operation .Then different nano‐silver colloids were acquired by dispersing the nano‐silver particles in water ,ethanol and ethylene glycol respectively through ultrasonic dispersion .For comparison ,the nano‐silver particles mass fraction of all the colloids was 0 .2 Wt% during the research .Nano‐silver particles were characterized by laser par‐ticle size analyzer ,transmission electron microscopy (TEM) and scanning electron microscopy (SEM);and the concentration of nano‐silver colloids was confirmed through synchronized thermal analyzer (STA) .The size distribution result of laser particle size analyzer showed that nano‐silver particles were about 100 nm and had uniform size distribution .The images of TEM and SEM showed that the size of nano‐silver particles was in nanoscale as well .To evaluate the dispersion stabilities of different nano‐silver colloids ,Turbiscan optical analyzer which was based on multiple light scattering analysis had been employed in the research ;and the principle factors leading to instabilities of nano‐silver colloids were also discussed .Results showed that particle size variation and particle migration were major factors which affected the dispersion stabilities of nano‐silver colloids .For the nano‐silver colloid dispersed in water phase ,the backscattering light signal in middle of the sample cell stayed unchanged with time while the backscattering light signals at top and bottom of the sample cell showed dramatic variation during the measure‐ment ,which indicated that particle migration was the main reason why the nano‐silver colloids was unstable .But for the nano‐silver colloids dispersed in ethanol and ethylene

  20. Electrically controlled dispersion in a nematic cell

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Carlos I. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-360, 04510 Mexico, D.F. (Mexico)]. E-mail: cmendoza@iim.unam.mx; Olivares, J.A. [Centro de Investigacion en Polimeros, COMEX, Blvd. M. Avila Camacho 138, PH1 y 2, Lomas de Chapultepec 11560, Mexico, D.F. (Mexico); Reyes, J.A. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 Mexico, D.F. (Mexico)

    2007-01-01

    In this work, we show theoretically how the trajectories of a propagating optical beam traveling in a planar-homeotropic hybrid nematic crystal cell depend on the wavelength of the optical beam. We apply a uniform electric field perpendicular to the cell to modify these trajectories. The influence of both, the electric field intensity and the refraction index dependence on the wavelength, give rise to an electrically tuned dispersion that may be useful for practical applications.

  1. Dispersing powders in liquids

    CERN Document Server

    Nelson, RD

    1988-01-01

    This book provides powder technologists with laboratory procedures for selecting dispersing agents and preparing stable dispersions that can then be used in particle size characterization instruments. Its broader goal is to introduce industrial chemists and engineers to the phenomena, terminology, physical principles, and chemical considerations involved in preparing and handling dispersions on a commercial scale. The book introduces novices to: - industrial problems due to improper degree of dispersion; - the nomenclature used in describing particles; - the basic physica

  2. SIMULATION ON NONLINEAR OPTICAL ABSORPTION OF BINARY METALS DISPERSED (Au, Ag, Cu)/SiO2 NANO-COMPOSITE FILMS BY MODIFIED MIE THEORY%(Au,Ag,Cu)/SiO2二元金属单分散复合薄膜非线性光吸收性的Mie理论模拟

    Institute of Scientific and Technical Information of China (English)

    严丽平; 张波萍; 王士京; 赵翠华; 李顺

    2011-01-01

    Due to the surface plasmon resonance (SPR) and enhanced local field effect of metal particles, nano-composite films exhibit a variety of properties, such as large third order nonlinear susceptibility, superfast response time and absorption peaks in the optical spectra at a special wavelength. Therefore they are attractive candidates for optical communication, such as information storage and optical device. In recent years, the metal nanoparticle nonlinear optical composite films have been developed rapidly, expanded from single metal nano particle dispersion system to the dual metal nano particle dispersion system. However, theoretical study on the nonlinear optical absorption of the dual metal nano particle dispersion system is quite rare. In this study, the optical absorption spectra of the (Ag, Cu)/SiO2, (Au, Cu)/SiO2 and (Ag, Au)/SiO2 binary metals dispersed nano-composite films were simulated by modified Mie theory. When the metal particles with a low full factor are smaller than the incident wavelength in diameters, the optical spectra of (Ag, Cu)/SiO2, (Au, Cu)/SiO2 and (Ag, Au)/SiO2 composite films in which the nanoparticles solely dispersed in each metal state, can be calculated and analyzed based on the modified Mie theory using the optical parameters of the component. Two SPR absorption peaks appear in the corresponding wavelength of the single metal dispersed nano-composite films.The intensities of SPR absorption peaks depend strongly on the relative content of binary metals,while their peak positions are constant regardless of the content. The calculated optical absorption spectra by proposed method in this study are in good agreement with the reported experiment results.It suggests that the linear superposition method is feasible to calculate the absorption spectra of other separated binary and/or multiplex metals dispersed nano-composite films.%采用修正的Mie理论模拟计算了(Ag,Cu)/SiO2,(Au,Cu)/SiO2和(Ag,Au)/SiO2二元单质金属纳米颗

  3. Pigment dispersion syndrome

    Directory of Open Access Journals (Sweden)

    C.S. Sandhya

    2013-10-01

    Full Text Available We report of the rare occurrence of pigment dispersion syndrome (PDS with posterior subcapsular cataract in both eyes in a young male patient. The patient presented with complaints of progressive decrease in vision of one year duration. The patient also had high myopia with mild iridodonesis, phacodonesis and anterior insertion of zonules. Classical signs of PDS like Krukenberg's spindle on the posterior corneal surface were evident on slit lamp examination; transillumination defects in the iris could not be elicited by retroillumination as the iris was heavily pigmented. Gonioscopy revealed heavy and uniform pigmentation of trabecular meshwork. Evidence of a characteristic iris configuration on optical coherence tomography (OCT, namely, posterior bowing of iris in the mid periphery suggested the diagnosis of PDS. This case highlights the importance of OCT in identifying the iris configuration characteristically seen in PDS even in the absence of transillumination defects in the iris and reiterates the need to look for subtle signs like phacodonesis which are important when surgical intervention is planned.

  4. Equalization of dispersion in single-mode fibers.

    Science.gov (United States)

    Marcuse, D

    1981-02-15

    Optical pulse equalization in single-mode fibers using positive and negative chromatic dispersion has been demonstrated by Lin et al. [Opt. Lett. 5, 476 (1980)]. In this paper, an earlier theory of pulse propagation in single-mode fibers is extended to the case of a tandem arrangement of N fibers with different dispersive properties. The theory includes first- and second-order dispersion. It is shown that, by using fibers with positive and negative chromatic dispersion, the first-order dispersion term cancels out on average.

  5. Dispersion y dinamica poblacional

    Science.gov (United States)

    Dispersal behavior of fruit flies is appetitive. Measures of dispersion involve two different parameter: the maximum distance and the standard distance. Standard distance is a parameter that describes the probalility of dispersion and is mathematically equivalent to the standard deviation around ...

  6. Seed dispersal in fens

    NARCIS (Netherlands)

    Middleton, Beth; van Diggelen, Rudy; Jensen, Kai

    2006-01-01

    Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and redu

  7. Phase Modulation for postcompensation of dispersion in 160-Gb/s systems

    DEFF Research Database (Denmark)

    Siahlo, Andrei; Clausen, A. T.; Oxenløwe, Leif Katsuo

    2005-01-01

    Tunable postcompensation of second-order dispersion by sinusoidal phase modulation is realized for a 160-Gb/s optical transmission system. Accumulated dispersions with magnitudes up to 4 ps/nm are compensated in the receiver end.......Tunable postcompensation of second-order dispersion by sinusoidal phase modulation is realized for a 160-Gb/s optical transmission system. Accumulated dispersions with magnitudes up to 4 ps/nm are compensated in the receiver end....

  8. Light Optics for Optical Stochastic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Andorf, Matthew [NICADD, DeKalb; Lebedev, Valeri [Fermilab; Piot, Philippe [NICADD, DeKalb; Ruan, Jinhao [Fermilab

    2016-06-01

    In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.

  9. Dispersion relations for circular single and double dusty plasma chains

    CERN Document Server

    Tkachenko, D V; Misko, V R

    2011-01-01

    We derive dispersion relations for a system of identical particles confined in a two-dimensional annular harmonic well and which interact through a Yukawa potential, e.g., a dusty plasma ring. When the particles are in a single chain (i.e., a one-dimensional ring) we find a longitudinal acoustic mode and a transverse optical mode which show approximate agreement with the dispersion relation for a straight configuration for large radii of the ring. When the radius decreases, the dispersion relations modify: there appears an anticrossing of the modes near the crossing point resulting in a frequency gap between the lower and upper branches of the modified dispersion relations. For the double chain (i.e., a two-dimensional zigzag configuration) the dispersion relation has four branches: longitudinal acoustic and optical and transverse acoustic and optical.

  10. Fast dispersive beam deflectors and modulators

    DEFF Research Database (Denmark)

    Filinski, Ignacy; Skettrup, Torben

    1982-01-01

    A new method for one-dimensional light scanning is proposed. It is based on the use of ordinary dispersive optical components like prisms, gratings, etc. By electrooptic tuning of the output wavelength of broad-band lasers, fast scanners (up to 10 gigapixels/s) can be constructed. Deflection angles...

  11. Frictionless dispersive hydrodynamics of Stokes flows

    CERN Document Server

    Maiden, Michelle D; Anderson, Dalton V; Schubert, Marika E; Hoefer, Mark A

    2016-01-01

    Effectively frictionless, dispersive flow characterizes superfluids, nonlinear optical diffraction, and geophysical fluid interfaces. Dispersive shock waves (DSWs) and solitons are fundamental nonlinear excitations in these media, but DSW studies to date have been severely constrained by a loss of coherence. Here we report on a novel dispersive hydrodynamics testbed: the effectively frictionless flow of interfacial waves between two high contrast, low Reynolds' number Stokes fluids. This system enables high fidelity observations of large amplitude DSWs, found to agree quantitatively with a nonlinear wave averaging theory. We then report on observations of highly coherent phenomena including DSW backflow, the refraction or absorption of solitons by DSWs, and multi-phase DSW-DSW merger. The complex, coherent, nonlinear mixing of DSWs and solitons observed here are universal features of dissipationless, dispersive hydrodynamic flows.

  12. Hyper dispersion pulse compressor for chirped pulse amplification systems

    Science.gov (United States)

    Barty, Christopher P. J.

    2011-11-29

    A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

  13. Preparation and study of properties of dispersed graphene oxide

    Directory of Open Access Journals (Sweden)

    Evgeniya Seliverstova

    2015-09-01

    Full Text Available Ability of graphene oxide to form stable dispersion in organic solvents was studied in this work. As it was shown, sonication of graphene leads to the decreas of the particle size. Stability of prepared graphene dispersions was studied upon measurements of distribution of number of the particles via size and change of optical density of the solutions with time. It was found that graphene oxide forms a more stable dispersion in tetrahydrofuran and dimethylformamide than in chloroform and acetone.

  14. Electrochromic blueshift in polymer-dispersed liquid-crystal cells.

    Science.gov (United States)

    Ramsey, R A; Sharma, S C

    2004-10-01

    Electrochromic blueshift in the absorption band of polymer-dispersed liquid-crystal cells is reported as a function of applied electric field. The changes in the peak absorption wavelength, absorption broadening, and their possible relationships with the nonlinear optical properties of polymer-dispersed liquid-crystal cells are discussed.

  15. Time-domain Wave Propagation in Dispersive Media①

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    The equation of time-domain wave propagation in dispersive media and the explicit beam propagation method are presented in this paper.This method is demonstrated by the short optical pulses in a directional coupler with second order dispersive effect and shows to be in full agreement with former references.This method is simple,easy and practical.

  16. Vowel dispersion in Truku

    OpenAIRE

    Chiang, Wen-yu; Chiang, Fang-mei

    2013-01-01

    This study investigates the dispersion of vowel space in Truku, an endangered Austronesian language in Taiwan. Adaptive Dispersion (Liljencrants and Lindblom, 1972; Lindblom, 1986, 1990) proposes that the distinctive sounds of a language tend to be positioned in phonetic space in a way that maximizes perceptual contrast. For example, languages with large vowel inventories tend to expand the overall acoustic vowel space. Adaptive Dispersion predicts that the distance between the point vowels w...

  17. Optical Dispersion Behavior and Band Gap Energy of Relaxor Ferroelectric 0.92Pb(Mg1/3Nb2/3)O3-0.08PbTiO3 Single Crystal

    Institute of Scientific and Technical Information of China (English)

    LIN Yan-Ting; REN Bo; ZHAO Xiang-Yong; WANG Fei-Fei; WANG Yao-Jin; XU Hai-Qing; LIN Di; LUO Hao-Su

    2009-01-01

    Refractive indices and extinction coefficients of 0.92Pb(Mg1/3 Nb2/a )O3-0.08Pb Ti03 (PMN-0.08PT) single crystal are investigated by variable angle spectroscopic ellipsometry (VASE) at different wavelengths. The parameters relative to the energy band structure are obtained by fitting to the single-oscillator dispersion equation, and the band gap energy is also deduced from the Tauc equation. Similar to most oxygen-octahedra ferroelectrics,PMN-0.08PT has the same dispersion behavior described by the refractive-index dispersion parameters.

  18. Impact of higher-order dispersion in the modulational instability spectrum of a relaxing coupled saturable media

    Indian Academy of Sciences (India)

    K Nithyanandan; R Vasantha Jayakantha Raja; T Uthayakumar; K Porsezian

    2014-02-01

    A theoretical analysis of modulational instability (MI) of optical pulses propagating near the zero dispersion wavelength of a lossless fibre with the effect of delayed saturable nonlinear response is presented. We calculate the exact dispersion relation with the effect of higher dispersion for the harmonic perturbation. We analysed the impact of fourth-order dispersion effects in the MI spectrum. We examine the possibility of MI in both dispersion regimes, regardless of the sign of the group velocity dispersion.

  19. The clusters-in-a-liquid approach for solvation: New insights from the conformer specific gas phase spectroscopy and vibrational optical activity spectroscopy

    Directory of Open Access Journals (Sweden)

    Yunjie eXu

    2016-02-01

    Full Text Available Vibrational optical activity spectroscopies, namely vibrational circular dichroism (VCD and Raman optical activity (ROA, have been emerged in the past decade as a powerful spectroscopic tool for stereochemical information of a wide range of chiral compounds in solution directly. More recently, their applications in unveiling solvent effects, especially those associated with water solvent, have been explored. In this review article, we first select a few examples to demonstrate the unique sensitivity of VCD spectral signatures to both bulk solvent effects and explicit hydrogen-bonding interactions in solution. Second, we discuss the induced solvent chirality, or chiral transfer, VCD spectral features observed at the water bending band region in detail. From these chirality transfer spectral data, the related conformer specific gas phase spectroscopic studies of small chiral hydration clusters, and the associated matrix isolation VCD experiments of hydrogen-bonded complexes in cold rare gas matrices, a general picture of solvation in aqueous solution emerges. In such an aqueous solution, some small chiral hydration clusters, rather than the chiral solutes themselves, are the dominant species and are the ones who contribute mainly to the experimentally observed VCD features. We then review a series of VCD studies of amino acids and their derivatives in aqueous solution under different pHs to emphasize the importance of the inclusion of the bulk solvent effects. These experimental data and the associated theoretical analyses are the foundation for the proposed clusters-in-a-liquid approach to account for solvent effects effectively. We present several approaches to identify and build such representative chiral hydration clusters. Recent studies which applied molecular dynamics simulations and the subsequent snapshot averaging approach to generate the ROA, electronic CD, and optical rotatory dispersion spectra are also reviewed. Challenges associated

  20. Optical properties of solids

    CERN Document Server

    Wooten, Frederick

    1972-01-01

    Optical Properties of Solids covers the important concepts of intrinsic optical properties and photoelectric emission. The book starts by providing an introduction to the fundamental optical spectra of solids. The text then discusses Maxwell's equations and the dielectric function; absorption and dispersion; and the theory of free-electron metals. The quantum mechanical theory of direct and indirect transitions between bands; the applications of dispersion relations; and the derivation of an expression for the dielectric function in the self-consistent field approximation are also encompassed.

  1. Extending of flat normal dispersion profile in all-solid soft glass nonlinear photonic crystal fibres

    Science.gov (United States)

    Siwicki, Bartłomiej; Kasztelanic, Rafał; Klimczak, Mariusz; Cimek, Jarosław; Pysz, Dariusz; Stępień, Ryszard; Buczyński, Ryszard

    2016-06-01

    The bandwidth of coherent supercontinuum generated in optical fibres is strongly determined by the all-normal dispersion characteristic of the fibre. We investigate all-normal dispersion limitations in all-solid oxide-based soft glass photonic crystal fibres with various relative inclusion sizes and lattice constants. The influence of material dispersion on fibre dispersion characteristics for a selected pair of glasses is also examined. A relation between the material dispersion of the glasses and the fibre dispersion has been described. We determined the parameters which limit the maximum range of flattened all-normal dispersion profile achievable for the considered pair of heavy-metal-oxide soft glasses.

  2. Seed dispersal in fens

    Science.gov (United States)

    Middleton, B.; Van Diggelen, R.; Jensen, K.

    2006-01-01

    Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and reducing genetic exchange. Species in fragmented wetlands may have lower reproductive success, which can lead to biodiversity loss. While fens may have always been relatively isolated from each other, they have become increasingly fragmented in modern times within agricultural and urban landscapes in both Europe and North America. Dispersal by water, animals and wind has been hampered by changes related to development in landscapes surrounding fens. Because the seeds of certain species are long-lived in the seed bank, frequent episodes of dispersal are not always necessary to maintain the biodiversity of fens. However, of particular concern to restoration is that some dominant species, such as the tussock sedge Carex stricta, may not disperse readily between fens. Conclusions: Knowledge of seed dispersal can be used to maintain and restore the biodiversity of fens in fragmented landscapes. Given that development has fragmented landscapes and that this situation is not likely to change, the dispersal of seeds might be enhanced by moving hay or cattle from fens to damaged sites, or by reestablishing lost hydrological connections. ?? IAVS; Opulus Press.

  3. Visualizing Dispersion Interactions

    Science.gov (United States)

    Gottschalk, Elinor; Venkataraman, Bhawani

    2014-01-01

    An animation and accompanying activity has been developed to help students visualize how dispersion interactions arise. The animation uses the gecko's ability to walk on vertical surfaces to illustrate how dispersion interactions play a role in macroscale outcomes. Assessment of student learning reveals that students were able to develop…

  4. Visualizing Dispersion Interactions

    Science.gov (United States)

    Gottschalk, Elinor; Venkataraman, Bhawani

    2014-01-01

    An animation and accompanying activity has been developed to help students visualize how dispersion interactions arise. The animation uses the gecko's ability to walk on vertical surfaces to illustrate how dispersion interactions play a role in macroscale outcomes. Assessment of student learning reveals that students were able to develop…

  5. Evolution of dispersal distance.

    Science.gov (United States)

    Durrett, Rick; Remenik, Daniel

    2012-03-01

    The problem of how often to disperse in a randomly fluctuating environment has long been investigated, primarily using patch models with uniform dispersal. Here, we consider the problem of choice of seed size for plants in a stable environment when there is a trade off between survivability and dispersal range. Ezoe (J Theor Biol 190:287-293, 1998) and Levin and Muller-Landau (Evol Ecol Res 2:409-435, 2000) approached this problem using models that were essentially deterministic, and used calculus to find optimal dispersal parameters. Here we follow Hiebeler (Theor Pop Biol 66:205-218, 2004) and use a stochastic spatial model to study the competition of different dispersal strategies. Most work on such systems is done by simulation or nonrigorous methods such as pair approximation. Here, we use machinery developed by Cox et al. (Voter model perturbations and reaction diffusion equations 2011) to rigorously and explicitly compute evolutionarily stable strategies.

  6. Optical systems for synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R.

    1985-12-01

    Various fundamental topics which underlie the design and use of optical systems for synchrotron radiation are considered from the viewpoint of linear system theory. These topics include the damped harmonic oscillator, free space propagation of an optical field, electromagnetic theory of optical properties of materials, theory of dispersion, and the Kramers-Kronig relations. 32 refs., 5 figs. (LEW)

  7. Finite element analysis of lumbar pelvic and proximal femur model with simulate lumbar rotatory manipulation%旋转手法对腰椎骨盆和股骨上端结构有限元模型的分析

    Institute of Scientific and Technical Information of China (English)

    胡华; 熊昌源; 韩国武

    2012-01-01

    目的:研究腰椎旋转手法时腰椎骨盆和股骨上端各结构位移和应力的特点.方法:使用腰椎CT片,以Mimics 10.01软件建立腰椎骨盆和股骨上端几何模型,经Geomagic 9对模型进行修改后导入Hypermesh 10划分4面体网格并添加椎间盘与韧带.根据手法作用原理,将腰椎旋转手法进行分解,把各项力学参数导入三维有限元模型.利用Abaqus求解模块对4工况下模型的位移和应力进行计算分析,得到腰椎旋转手法作用时腰椎骨盆和股骨上端各结构位移和应力的变化.结果:①相同工况下腰椎位移的大小顺序是:L1>L2>L3>L4>L5,前柱>中柱>后柱.②不同工况下腰椎的位移大小顺序是:工况3>工况1>工况4>工况2.③相同工况下椎间盘从L1,2-L5S1各椎间盘位移大小顺序是:L1,2>L2,3>L3,4>L4,5>L5S1,同一椎间盘内各象限位移大小顺序为:第2象限>第3象限>第1象限>第4象限.④不同工况下各椎间盘的位移大小顺序是:L1,2>L2,3>L3,4>L4.5> L5S1,同一椎间盘不同工况下位移大小顺序是:工况3>工况4>工况1>工况2.⑤骨盆和髋关节在手法作用过程中存在明显的位移和应力集中.结论:①旋转手法的作用原理与腰椎骨盆和股骨上端各相应解剖部位因旋转而引起的相对位移有关;②在手法的操作过程中,不能随意加大侧弯和前屈的角度;③在腰椎旋转手法的施术过程中,必须综合考虑腰椎骨盆和股骨上端各部位的具体情况以确定适应证和禁忌证.%Objective: To study the changes of displacement and stress in the model of lumbar pelvic and proximal femur during lumbar rotatory manipulation. MethodS:The date of lumbar pelvic and proximal femur CT scan by Mimics 10.01 software was established a lumbar pelvic and proximal femur geometric model, then the model was modified with Geomagic 9, at last the modified model was imported into hypermesh 10 and meshed with

  8. Chromatic Dispersion Compensation Using Photonic Crystal Fibers with Hexagonal Distribution

    Directory of Open Access Journals (Sweden)

    Erick E. Reyes-Vera

    2013-11-01

    Full Text Available In this paper we show various configurations of photonic crystal fiber with hexagonal holes distribution for compensation of chromatic dispersion in optical communications links. The vectorial finite element method with scattering boundary condition was used for the analysis of the fibers. From these results it was estimated variation of the dispersion and the dispersion slope with respect to change in the diameter of the holes in the microstructure. With the above was possible to obtain values of dispersion in the C and L bands of telecommunications close to -850 ps / nm * km, with confinement losses 10-3 dB / km

  9. Dispersive shock waves and modulation theory

    Science.gov (United States)

    El, G. A.; Hoefer, M. A.

    2016-10-01

    There is growing physical and mathematical interest in the hydrodynamics of dissipationless/dispersive media. Since G.B. Whitham's seminal publication fifty years ago that ushered in the mathematical study of dispersive hydrodynamics, there has been a significant body of work in this area. However, there has been no comprehensive survey of the field of dispersive hydrodynamics. Utilizing Whitham's averaging theory as the primary mathematical tool, we review the rich mathematical developments over the past fifty years with an emphasis on physical applications. The fundamental, large scale, coherent excitation in dispersive hydrodynamic systems is an expanding, oscillatory dispersive shock wave or DSW. Both the macroscopic and microscopic properties of DSWs are analyzed in detail within the context of the universal, integrable, and foundational models for uni-directional (Korteweg-de Vries equation) and bi-directional (Nonlinear Schrödinger equation) dispersive hydrodynamics. A DSW fitting procedure that does not rely upon integrable structure yet reveals important macroscopic DSW properties is described. DSW theory is then applied to a number of physical applications: superfluids, nonlinear optics, geophysics, and fluid dynamics. Finally, we survey some of the more recent developments including non-classical DSWs, DSW interactions, DSWs in perturbed and inhomogeneous environments, and two-dimensional, oblique DSWs.

  10. Clinical Observation on TuiNa and Rotatory Manual Reduction in Treating Lumbar Disc Herniation%推拿结合旋转复位手法治疗腰椎间盘突出症的临床观察

    Institute of Scientific and Technical Information of China (English)

    张沛桃

    2012-01-01

    Objective: To explore clinical effects of TuiNa and rotatory manual reduction in treating lumbar disc herniation (LDH). Method: A total of 100 patients with LDH were randomly divided into treatment group and control group, 50 cases each group. Treatment group were given with manipulation including kneading, one-finger pushing manipulation to relax muscles and ligament, point-pressing manipulation at acupoints of She Shu (BL23), DaChangShu (BL25), HuanTiao(GB30), WeiZhong (BL40), KunLun(BL60) and others, fixed rotatory manual reduction and traction, traction weight from 30 to 60 kg, 30 min once, once per day, one session was 15 days, the interval was one to two days. Control group received traction. Clinical effects of both groups and changes of visual analogue scale (VAS) before and after treating were observed. Result: Cure rate of treatment group was 76.00%, higher than 50.00% of control group with statistical meaning (P<0.05); total effective rate of treatment group was 96.00%, superior to 74.00% of control group with statistical meaning (P<0.05). VAS of both groups after treating decreased compared with that before treating with statistical meaning (P<0.05); comparison between both groups suggested statistical meaning after the treatment (P<0.05). Conclusion: TuiNa and rotatory manual reduction can obtain notable clinical effects and can obviously alleviate the pain in treating LDH.%目的:观察推拿结合旋转复位手法治疗腰椎间盘突出症(LDH)的临床疗效.方法:将符合病例入选标准的100例LDH 患者随机分为治疗组、对照组各50 例.治疗组患者先用揉、一指禅推法等放松腰臀腿部肌肉韧带,同时在肾俞、大肠俞、环跳、委中、昆仑等穴位给予点按手法,再行定点旋转复位术,同时给予牵引治疗,牵引质量30~60 kg,30 min/次,1次/d,治疗15 天,中间休息1~2 天.对照组给予牵引治疗(方法同治疗组).观察2组临床疗效及治疗前后疼痛评分变化情况.结

  11. Rates of Gravel Dispersion

    Science.gov (United States)

    Haschenburger, J. K.

    2010-12-01

    Sediment transfers in gravel-bed rivers involve the three-dimensional dispersion of mixed size sediment. From a kinematics standpoint, few studies are available to inform on the streamwise and vertical rates of sediment dispersion in natural channels. This research uses a gravel tracing program to quantify dispersion rates over 19 flood seasons. Empirical observations come from Carnation Creek, a small gravel-bed river with large woody debris located on the west coast of Vancouver Island, Canada. Frequent floods and the relatively limited armor layer facilitate streambed activity and relatively high bedload transport rates, typically under partial sediment transport conditions. Over 2500 magnetically tagged stones, ranging in size from 16 to 180 mm, were deployed on the bed surface between 1989 and 1992 in four generations. To quantify gravel dispersion over distances up to 2.6 km, observations are taken from 11 recoveries. Over 280 floods capable of moving bedload occurred during this period, with five exceeding the estimated bankfull discharge. Streamwise dispersion is quantified by virtual velocity, while dispersion into the streambed is quantified by a vertical burial rate. The temporal trend in streamwise dispersion rates is described by a power function. Initial virtual velocities decline rapidly from around 1.4 m/hr to approach an asymptote value of about 0.2 m/hr. The rapid change corresponds to a significant increase in the proportion of buried tracers due to vertical mixing. Initial burial rates reflect the magnitude of the first flood after tracer deployment and range from 0.07 to 0.46 cm/hr depending on tracer generation. Burial rates converge to about 0.06 cm/hr after the fourth flood season and then gradually decline to about 0.01 cm/hr. Thus, the rate of streamwise dispersion exceeds that of vertical dispersion by three orders of magnitude when the movement of sediment routinely activated by floods is considered.

  12. Dispersive hydrodynamics: Preface

    Science.gov (United States)

    Biondini, G.; El, G. A.; Hoefer, M. A.; Miller, P. D.

    2016-10-01

    This Special Issue on Dispersive Hydrodynamics is dedicated to the memory and work of G.B. Whitham who was one of the pioneers in this field of physical applied mathematics. Some of the papers appearing here are related to work reported on at the workshop "Dispersive Hydrodynamics: The Mathematics of Dispersive Shock Waves and Applications" held in May 2015 at the Banff International Research Station. This Preface provides a broad overview of the field and summaries of the various contributions to the Special Issue, placing them in a unified context.

  13. Reversed dispersion slope photonic bandgap fibers for broadband dispersion control in femtosecond fiber lasers.

    Science.gov (United States)

    Várallyay, Z; Saitoh, K; Fekete, J; Kakihara, K; Koshiba, M; Szipocs, R

    2008-09-29

    Higher-order-mode solid and hollow core photonic bandgap fibers exhibiting reversed or zero dispersion slope over tens or hundreds of nanometer bandwidths within the bandgap are presented. This attractive feature makes them well suited for broadband dispersion control in femtosecond pulse fiber lasers, amplifiers and optical parametric oscillators. The canonical form of the dispersion profile in photonic bandgap fibers is modified by a partial reflector layer/interface placed around the core forming a 2D cylindrical Gires-Tournois type interferometer. This small perturbation in the index profile induces a frequency dependent electric field distribution of the preferred propagating higher-order-mode resulting in a zero or reversed dispersion slope.

  14. Adiabatic theory of solitons fed by dispersive waves

    Science.gov (United States)

    Pickartz, Sabrina; Bandelow, Uwe; Amiranashvili, Shalva

    2016-09-01

    We consider scattering of low-amplitude dispersive waves at an intense optical soliton which constitutes a nonlinear perturbation of the refractive index. Specifically, we consider a single-mode optical fiber and a group velocity matched pair: an optical soliton and a nearly perfectly reflected dispersive wave, a fiber-optical analog of the event horizon. By combining (i) an adiabatic approach that is used in soliton perturbation theory and (ii) scattering theory from quantum mechanics, we give a quantitative account of the evolution of all soliton parameters. In particular, we quantify the increase in the soliton peak power that may result in the spontaneous appearance of an extremely large, so-called champion soliton. The presented adiabatic theory agrees well with the numerical solutions of the pulse propagation equation. Moreover, we predict the full frequency band of the scattered dispersive waves and explain an emerging caustic structure in the space-time domain.

  15. Radiation pressure of active dispersive chiral slabs.

    Science.gov (United States)

    Wang, Maoyan; Li, Hailong; Gao, Dongliang; Gao, Lei; Xu, Jun; Qiu, Cheng-Wei

    2015-06-29

    We report a mechanism to obtain optical pulling or pushing forces exerted on the active dispersive chiral media. Electromagnetic wave equations for the pure chiral media using constitutive relations containing dispersive Drude models are numerically solved by means of Auxiliary Differential Equation Finite Difference Time Domain (ADE-FDTD) method. This method allows us to access the time averaged Lorentz force densities exerted on the magnetoelectric coupling chiral slabs via the derivation of bound electric and magnetic charge densities, as well as bound electric and magnetic current densities. Due to the continuously coupled cross-polarized electromagnetic waves, we find that the pressure gradient force is engendered on the active chiral slabs under a plane wave incidence. By changing the material parameters of the slabs, the total radiation pressure exerted on a single slab can be directed either along the propagation direction or in the opposite direction. This finding provides a promising avenue for detecting the chirality of materials by optical forces.

  16. Dispersion forces in methane

    NARCIS (Netherlands)

    Lekkerkerker, H.N.W.; Coulon, P.; Luyckx, R.

    1977-01-01

    The coefficients of the R-6 and R-7 terms in the series representation of the dispersion interaction between two methane molecules and between methane and helium, neon and argon are calculated by a variation method.

  17. Optics/Optical Diagnostics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Optics/Optical Diagnostics Laboratory supports graduate instruction in optics, optical and laser diagnostics and electro-optics. The optics laboratory provides...

  18. Cotton Effect in Copper-Proline Complexes in the Visible Region

    Science.gov (United States)

    Volkov, Victor; Pfister, Rolf

    2005-01-01

    The electronic properties of Cu(II) complex with proline are considered to demonstrate the Cotton effect in the visible region. A series of experiments in optical rotatory dispersion spectroscopy with free D- and L-proline and their complexes with the Cu(II) ion in aqueous solution is suggested.

  19. Quantum Statistical Theory of Polarization Mode Dispersion

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Sheng; GUO Guang-Can

    2006-01-01

    @@ Polarization mode dispersion is modelled as decoherence of polarization under the disturbance of environment and the coupling with frequency. This model is described by the quantum master equation and the Langevin equation. It can be predicted that the optical beam is depolarized exponentially in a fibre and the differential group delay (DGD) is proportional to the square root of the propagation distance. The distribution of the DGD can also be calculated.

  20. Fickian dispersion is anomalous

    Science.gov (United States)

    Cushman, John H.; O'Malley, Dan

    2015-12-01

    The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion we illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.