bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Mechanism of Intrinsic Bistability of Nonlinear Slugged Structures under the Action of Repetitive Pulse Excitation
Authors: Gainer A. V. , Surdutovich G. I. 
Published: July 2007

AbstractA new type of the cavityless bistability is proposed where the nonlinear medium does not show intrinsic bistability under action of a continuous input signal but shows bistability under action of a time‐dependent input signal. A strict criterion for the observation of such a bistability is given. It depends on the shape of the temporal response of the nonlinear medium under action of the isolated rectangular input pulse.
Effects of Spatial Distributivity in Semiconductor Optical Bistable Systems
Authors: Rosanov N. N. , Fedorov A. V. , Khodova G. V. 
Published: July 2007

AbstractResults are presented of a theoretical analysis of transverse and longitudinal distributivity effects in semiconductor optical bistable systems. For a resonatorless increasing absorption bistable system the kinetics of autopulsations (resulting from the formation of moving absorption domains) are described. For wideaperture nonlinear interferometers new types of field spatial structures are shown: immovable and moving autosolitons, waves of automodulation and autostochasticity, and pulsing distributions.
Exciton–Phonon Mechanism of Optical Bistability
Authors: Nitsovich B. M. , Krechivskii O. V. , Pestryakov G. M. 
Published: July 2007

AbstractA joint effect of exciton–phonon and exciton–exciton interactions on optical properties of semiconductors is studied. In these substances the exciton density is shown to be a multivalued function of incident light intensity and the frequency and temperature conditions under which the optical bistability arises are specified. Investigation of nonlinear optical properties of semiconductors with account for the indirect phototransitions exhibits that both multistable optical states and the bistable ones distinguished by a complicated dynamics of the switching may be observed in such systems.
Analysis of Absorptive Bistability in a Two‐Section Semiconductor Injection Laser
Authors: Šrobár F. 
Published: July 2007

AbstractThe phenomenon of absorptive bistability in a two‐section injection laser is analysed employing the method of causal diagrams. Steady‐state rate equations for electrons in the gain (n1) and in the saturable absorber (n2) sections and for photons (np) can be represented by diagrams containing feedback loop attached to vertex np and encompassing vertex n2. Numerical analysis of typical cases confirms the crucial role played by the feedback relationships in producing the bistable regime.
On the Possibility of the Optical Connection between SEED'S within One Array
Authors: Butusov D. M. , Gotsadze G. G. , Larionov V. R. , Ryvkin B. S. 
Published: July 2007

AbstractThe principle of optical waveguide connection among the semiconductor switching elements SEED integrated within two‐dimensional array is proposed. The first preliminary experimental results are given that confirm the realisation possibility of such a connection.
Quasisoliton Mechanism of Generation of Bistable Injection Laser with External Cavity
Authors: Velichanskii V. L. , Gainer A. V. , Saptsov V. I. , Sautenkov V. A. , Seregin V. F. , Solodkov V. F. , Surdutovich G. I. 
Published: July 2007

AbstractIn an arbitrary distributed bistable system – passive or active – the existence of quasirectangular pulse (dip) with a duration less than the by‐pass time of the resonator is predicted. Such a quasisoliton regime is realized experimentally in the system with bicompound injection laser and external cavity.
Photoinduced Charge Dynamics in Photorefractive Semiconductors
Authors: Astratov V. N. , Ilinskii A. V. , Furman A. S. 
Published: July 2007

AbstractPhotoinduced charge dynamics in photorefractive semiconductors is studied from both, theoretical and experimental points of view in the case of an external field screening. This dynamics shows two different regimes depending on the parameter τM/τi where τM is the Maxwellian time and τi is the impurity ionization time. For τM ≪τi, the stratification effect arises and numerous space charge layers of alternating sign occur in the crystal. Another regime occurs for τi ≪ τM, the broadening of the single layer leads to the screening. In BSO, the first regime takes place for room crystal temperatures T, and the second one for 130 K < T < 200 K. Such charge dynamics determines optical nonlinearity of photorefractive semiconductors.
The Optical Bistability in the Active and Absorptive Tandem Semiconductor Lasers
Authors: Zhang Xiaobo , Flint I. 
Published: July 2007

AbstractExperimental results and a theoretical analysis are given of the active and absorptive ridge waveguide tandem semiconductor lasers. It is found that the relative hysteresis width in the optical output of the laser depends on the parameters of the laser structure such as the relative length of the two regions and also the pumping levels. Especially, a small extraction current from the passive part causes the enhancement of the bistability. Both, the experimental and theoretical results suggest that there is an optimum selection of the relative length of the two regions and of the current level applied on the passive region, if a maximum hysteresis is required.
Nonlinear Optics of Semiconductor‐Doped Glasses
Authors: Ekimov A. I. , Efros A. L. 
Published: July 2007

AbstractNonlinear optical properties of semiconductor‐doped glasses are reviewed. A growth technique enabling to obtain semiconductor microcrystals with controlled sizes grown in a glassy matrix is described. It is shown that the optical properties of such systems are determined by the energy spectrum of the electron–hole pairs confined in the small‐size microcrystals. The dependences of these spectra on the microcrystal size are analysed. The effect of the blue‐shift of the spectra occurring at high excitation levels is discussed. At excitation with light of photon energy below the energy gap of the glass photoionization is discovered. In this process the electron is ejected from the microcrystal to the glass where it is captured by the long‐lived centers. The latter process is likely to explain the effect of the glass darkening and the formation of permanent volume grating.
Large Optical Nonlinearity of the Two‐Dimensional Exciton States at a Stacking Fault Interface in BiI3
Authors: Iakai I. , Karasawa T. , Komatsu T. , Kaifu Y. 
Published: July 2007

AbstractThe optical Stark effect of an exciton system localized at a stacking fault (stacking fault excitons, SFE) in BiI3 crystals is presented. The SFE states show three very sharp absorption lines called R, S, and T. The excitation laser frequency dependence of the peak shift of the absorption line T is observed in a wide frequency range covering the three SFE states. The peak shift can be seen even for far off‐resonance excitation, and shows drastic change for the on‐resonance excitation of R, S, and T states. This behaviour can be explained by a “dressed exciton” model. The excitation intensity dependence of the peak shift manifests a very large nonlinear optical polarizability of the SFE system.
Optical Nonlinearity of Semiconductor Microcrystals CdSxSe1−x under the Action of Picosecond and Nanosecond Laser Pulses
Authors: Gribkovskii V. P. , Zyulkov V. A. , Kazachenko A. E. , Tikhomirov S. A. 
Published: July 2007

AbstractSize effects in microcrystal luminescence relaxation are observed. A change in the character of bleaching in glasses at excitation of carriers with energy higher by 0.2 to 0.5 eV than the absorption edge is detected. Transient bleaching spectra are measured and mechanisms of nonlinearity are elucidated.
Optical Investigation of Exciton Screening in GaAs/GaAlAs MQW Structures
Authors: Lach E. , Walther M. , Träkle G. , Forchel A. , Weimann G. 
Published: July 2007

AbstractIn transmission experiments performed under quasi‐equilibrium conditions the bleaching of the quasi‐2D excitons in GaAs/GaAlAs MQW structures is studied with special emphasis on the behavior of the excitons at different subband edges. The 11h‐excitons are found to be much more sensitive to bleaching than the higher excitons. This is attributed to phase space filling effects which reduce the oscillator strength of the 11h‐excitons additionally to the usual screening due to longrange Coulomb interaction.
Dynamics of Incoherent Excitonic Optical Nonlinearities in GaAs–GaAlAs MQWS's
Authors: Henneberger K. , Manzke G. 
Published: July 2007

AbstractThe dynamics of optical nonlinearities connected with the blue‐shift of the exciton line in resonantly excited GaAs–GaAlAs MQWS's is investigated theoretically simulating a two‐beam experiment. Jumps in the optical spectra of a weak test pulse (optical switching), which follows the intense pump pulse at different time delays, are observed, basing on a strong increase of the absorption. A similar mechanism of the bistability is observed in connection with the electro‐absorptive effect.
Time‐Resolved Photoluminescence of a GaAs/GaAlAs Superlattice
Authors: Weinert H. , Latinis V. , Juršenas S. , Baltramiejunas R. 
Published: July 2007

AbstractThe photoluminescence of a GaAs/GaAlAs superlattice at TL = 4.2 K is investigated at different excitation intensities with ps time resolution. The observed complicated time behaviour of the excitonic luminescence depends sensitively on excitation intensity. For a qualitative explanation of the experimental results different screening mechanisms and a time‐delayed capture of carriers into the quantum wells should be taken into account.
Optical Nonlinearity and Fast Switching in PbSnTe Fabry‐Perot Etalon
Authors: Paskov P. P. , Pavlov L. I. , Atanasov P. A. , Kushev D. B. , Zheleva N. N. 
Published: July 2007

AbstractOptical bistability is observed in a PbSnTe etalon at room temperature by two‐photon exitation with tunable TEA CO2 laser. The experimental results are compared with a numerical model which also takes into account the heating of the sample.
Mechanism of Optical Nonlinearity in CdS Due to Increasing Absorption at Room Temperature
Authors: Yang F. , Xiong G. , Xu X. 
Published: July 2007

AbstractTransmission and luminescence properties of CdS around the fundamental absorption edge at room temperature are investigated. Experimental results suggest that increasing absorption non‐linearity is related to two mechanisms. One is ascribed to the absorption red shift of exciton–electron (ex–el) scattering with increasing input laser intensity. A qualitative analysis and discussion about the nonlinearity due to ex–el scattering are given. The other is lattice heating of samples with cw laser illumination. The optical bistability due to thermal effect is observed.
Nonlinear Effects in the Emission Spectra of High Density Excitons in CdS Crystals
Authors: Nelson D. K. , Klochikhin A. A. , Mikhailov G. V. , Panfilov A. G. , Razbirin B. S. 
Published: July 2007

AbstractInvestigations of exciton ground state fine structure and exciton–phonon emission of CdS are carried out at e–h concentrations below or close to the Mott threshold. A considerable (about 0.5 meV) shift of the longitudinal exciton emission line AL towards the low energy is discovered when the excitation intensity increases up to 100 kW/cm2. This shift is accounted for by the reduction of the excitonic oscillator strength produced by screening effect. An enormous growth of the integral intensity of A‐LO luminescence band is observed with increasing excitation power. Possible reasons of the A‐LO band enhancement are considered.
Nonlinear Optical Effects in Amorphous Semiconductors
Authors: Jánossy I. 
Published: July 2007

AbstractIn amorphous semiconductors electronic optical nonlinearities are used as a spectroscopic tool rather than a non‐linear effect. On the other hand light‐induced rearrangement of certain atomic positions, a unique process occuring only in the amorphous state, has a strong effect on the optical properties. Such “photostructural changes” are reversible in bulk samples or well‐annealed films. This fact makes possible to switch the irradiated spot between two states by using light signals of different amplitudes, wavelengths or polarizations. The possibility of using these effects as a part of optical circuits is pointed out.
Optical Response of Nonlinear Absorbing and Saturable Multilayer Systems
Authors: Trutschel U. , Lederer F. , Langbein U. 
Published: July 2007

AbstractOblique‐incidence transmissivity and reflectivity of a multilayer system consisting of N unit cells is investigated. Each unit cell is formed of two absorbing, saturable nonlinear films. In detail the optical response of a multilayer system in investigated, illuminated by a plane wave close to the edge of the stop gap, in dependence on the input flux. It is shown that the combined effects of linear/nonlinear absorption and saturation will considerably affect bistable switching from the low‐transmission to the high‐transmission state. Eventually just this switching can disappear.
Nonlinear Optical Behaviour of Absorbing CdSxSe1−x Interference Filters
Authors: Ferencz K. , Szipöcs R. 
Published: July 2007

AbstractFirst experimental results of nonlinear, thin film interference filter wedges with mixed CdSxSe1−x as spacer material at the 633 nm wavelength of He–Ne laser are reported. Optical bistability is observed with less than 7.5 mW of optical power in single‐cavity structures. The change in refractive index is found to be positive which is in accordance with the thermal mechanism of nonlinearity. Producing a double‐cavity structure a device is obtained which works as an optical astable multivibrator having periodical change of transmission as the function of time.
Nonlinear Optical Properties of CdS and Optical Bistability
Authors: Dneprovskii V. S. , Furtichev A. I. , Klimov V. I. , Li Shen , Nazvanova E. V. , Okorokov D. K. , Vandishev U. V. 
Published: July 2007

AbstractFast and slow types of nonlinear absorption and resonatorless optical bistability of electronic and thermal origin is observed.
Exciton Nonequilibrium Steady States in Laser‐Excited Molecular Crystals
Authors: An Nguyen Ba 
Published: July 2007

AbstractNonequilibrium steady states of excitons in laser‐excited three‐dimensional molecular crystals are investigated not resorting to the usual boson description but using the exact trilinear commutation relations for exciton operators. The nonequilibrium property, non‐bosonity, and optical nonlinearity of the many‐exciton system under the action of an external classical laser field are considered on the same footing. Eigenfrequencies and dampings of the giant polariton are found to be dependent on the excitation degree. Conditions are determined for two types of bistability: density–light and light–light bistability.
Nonlinear Phenomena in Single‐Mode Optical Fibers
Authors: Tomlinson W. J. 
Published: July 2007

AbstractThe low losses of optical fibers made of silica glasses make it possible to study, and use, nonlinear optical phenomena at lower optical power levels than are required for most other materials, despite their very small nonlinearities. Some of the more important and/or interesting nonlinear phenomena observed in single‐mode optical fibers are reviewed, including pulse compression, bright soliton propagation, ultrafast all‐optical switching, and new results on dark soliton propagation.
Optical Bistability in Two‐Dimensional Waveguide Structures
Authors: Trutschel U. , Golz M. , Abraham M. 
Published: July 2007

AbstractA device with optical bistability is proposed well adapted to planar technology in the framework of integrated optics. The device is composed by a dielectric layer of Al2O3 deposited onto an InSb waveguide with defocussing Kerr‐nonlinearity and a metal substrate. It works at the wavelength of 10.6 μm, where the refractive index of Al2O3 is lower than in air and coupling into a waveguide‐mode without prism is possible. The reflectivity in dependence on the input power density is investigated. The shape of the resonance curve can be tuned by the angle of incidence. This should permit the implementation of a modulator, latching switch, logic gate, and power limiter within a fixed configuration.
Experimental Investigations of Optical Nonlinearities in Semiconductor‐Doped Glass Waveguides
Authors: Dannberg P. , Possner T. , Bräuer A. , Bartuch U. 
Published: July 2007

AbstractBoth, thermal and electronic optical nonlinearities are studied in semiconductor‐doped glass (SDG) waveguides which are fabricated in commercially available sharp‐cut filters by Cs+–K+ ion exchange. The relaxation time in photodarkened substrates is measured to be 30 ps. By means of a prism coupling set‐up the saturation value of the nonlinear index change is determined. Furthermore, a high stability dual‐beam interferometer is presented for the measurement of both, thermal and electronic nonlinear refractive index n2 in planar waveguides. Conclusions about the application of SDG to opto‐optical switching are given.
Investigation of the Field‐Dependent Carrier Mobility in GaAs by Picosecond Photoconductivity Measurements
Authors: Bergner H. , Brückner V. , Lenzner M. , Strobel R. 
Published: July 2007

AbstractThe carrier velocity is measured in Cr‐compensated GaAs in dependence on the applied field strength by picosecond photoconductivity measurements. Two different behaviours are obtained in dependence on the excitation energy. In the case of low excitation a region of negative differential conductivity due to the electron transfer from L‐valley into the L‐valley exists. In the case of high excitation the formation of charge domains lowers the mobility.
Picosecond Holographic Diagnostic of Light Pulse Absorption in Semiconductors
Authors: Bugaev A. A. , Zakharchenya B. P. 
Published: July 2007

AbstractThe results of using picosecond holographic interferometry in traditional excite‐and‐probe technique for the study of light pulse absorption in semiconductors are presented. The method allows to record the two‐dimensional distribution of transient light‐induced refractive index in a volume of the semiconductors which corresponds to the known time‐delay between exciting and probing pulses. The distribution obtained is compared with calculations based on Drude's relation and the solution of the system of equations describes the process of single (Si)‐ or two‐photon (GaAs) light pulse absorption. As a result it is possible to determine either some nonlinear parameters of semiconductor or parameters of the exciting pulse.
Picosecond Optical Nonlinearities and Stimulated Emission in Indirect AlxGa1−xAs
Authors: Kalt H. , Smirl A. L. , Boggess T. F. 
Published: July 2007

AbstractThe nonlinear optical properties of indirect‐gap AlxGa1−xAs in the presence of a dense electron‐hole plasma are studied by picosecond luminescence and transient transmission spectroscopy. The fundamental X‐band gap is found to be renormalized by exchange and correlation effects within the plasma. Higher‐lying band gaps in the same sample are also renormalized but here the electron‐exchange contribution to the narrowing is negligible. Strong plasma‐induced nonlinearities like persistent bleaching of absorption, enhanced absorption, and large changes of the refractive index are observed at the direct absorption edge for lattice temperatures of 15 as well as 293 K. Stimulated emission from the indirect X‐band is made possible by alloy‐disorder induced band mixing.
Light‐Induced Thermal Gratings in Natural Diamond
Authors: Gorbachev V. V. , Durasov V. M. , Zezin R. B. , Ivakin E. V. , Rubanov A. S. , Tatyanina N. A. 
Published: July 2007

AbstractFor the first time thermal dynamic gratings in Ia‐type diamond are recorded. Thermal diffusivity of eight samples is measured by diffraction of a cw laser beam from light‐induced spatially periodic temperature distributions. The connection between absorption of the 8.5 μm, wavelength and the thermal resistance of the crystals is demonstrated. No strict correlation is observed due to the influence of defects on the heat transfer in diamond which do not appear in the IR spectrum.
Possible Anomalies in Multicomponent Diffusion
Authors: Kvasnica J. 
Published: July 2007

AbstractThe evolution of concentrations in multicomponent diffusion depends on a characteristic parameter Δ constructed in terms of the diffusion coefficients Dik. For ternary diffusion Δ = (D22  D11)2 + + 4D12D21 where D12D21 can have both signs. In the case Δ > 0 one gets the normal monotonous evolution of concentrations, Δ < 0 leads to damped oscillations, at Δ = 0 there appear maxima and minima of concentrations for some values x2/t.
Suzuki Phase Precipitates in Doubly Doped KCI: Pb2+, Mn2+ Crystals
Authors: Cywiński R. , Mugeński E. , Nowy‐Wiechula W. , Wiechula J. 
Published: July 2007

AbstractKCl crystals doubly doped with Pb2+ and Mn2+ ions are examined by EPR and optical (emission and absorption spectra) methods. The presence of a Pb2+ rich phase containing Mn2+ ions in a cubic crystal field is ascertained. According to the results obtained one should expect the existence of trace amounts of the Suzuki phase (6 KCl · PbCl2 doped with Mn2+ ions) distributed in a quasilinear form along dislocations or (and) grain boundaries present in the matrix.
Dynamic Structure Factor of a Slowly Moving Soliton in a Thermal Bath
Authors: Dzyub I. P. , Zerov Yu. E. 
Published: July 2007

AbstractThe quasielastic and inelastic scattering functions of neutrons which interact with local and extended vibrations around kink‐like lattice displacement are examined within the φ4‐theory. The polaronic renormalization of the kink mass and explicit expressions for the scattering functions are obtained.
On the Ideal Strength of Crystals
Authors: Pokluda J. , Šandera P. 
Published: July 2007

AbstractA simplified model of f.c.c., b.c.c., and diamond crystalline structures is used to obtain a dependence of the ideal cohesive strength on some easily measurable quantities. The proposed conception is physically more justified as the well known Kelly‐Orowan approach. On the basis of the relationship between cohesive energy, bulk elasticity modulus, and atomic concentration, a very simple expression for the approximative determination of the ideal strength can be found.
Two‐Component Solitary Excitations in Molecular‐Bonded Chains
Authors: Ichinose S. 
Published: July 2007

AbstractTwo‐component solitary excitations are studied analytically in the continuum version of the Takeno model for molecular‐bonded chains. The vibronic structure of the model system is exactly calculated in the presence of the inhomogeneity in the distortion pattern of a chain. The small oscillations around a static soliton are considered as the eigenvalue problem for linear modes.
Coordination Symmetry and Energy Spectrum Analysis of Fe2+ in ZnS: Fe2+ Crystals
Authors: Zhao Sang‐Bo , Wang Hui‐Su , Xie Jun‐Kai 
Published: July 2007

AbstractThe Td symmetry complex model suggested by previous works is unable to give an unified theoretical analysis of the abundant absorption bands of Fe2+ ions mixed into ZnS. Many bands cannot be assigned by this model. As an improvement, a C2v model is used in the present paper by which, after considering the spin‐orbit coupling and the vibronic coupling, all of the bands (about 80) obtain a unified theoretical explanation; and also the shift direction of Fe2+ due to the crystal site distortion is determined. In the calculation a simplified strong field scheme including spin‐orbit coupling is applied to establish the complete C(d6) strong field matrices. All the related crystal field parameters are determined by the observed spin‐allowed bands. Thus the difficulty in low symmetry problems caused by the large number of parameters to be determined is removed and the prediction ability of the theory is well improved.