Optical properties and electronic structures of silicon quantum materials are reviewed. Crystalline silicon (c-Si) and amorphous silicon (a-Si) based zero-dimensional (0D) nanoparticles and two-dimensional (2D) quantum-wells were prepared and their photoluminescence (PL) properties were studied by means of resonant excitation spectroscopy. The PL peak energies of c-Si and a-Si nanoparticles and quantum wells are blueshifted from those of bulk c-Si and a-Si. TO-phonon related structures appear in resonantly excited luminescence spectra of H-passivated c-Si and a-Si nanoparticles. This indicates that visible luminescence is due to excitons confined in the interior c-Si and a-Si states. In SiO₂-passivated c-Si and a-Si nanoparticles, fine structures due to Si-O-Si vibrations appear in resonant luminescence spectra. In 0D Si/SiO₂ systems, excitons are localized at the interface between the Si interior and surface SiO₂ layer. In 2D Si/SiO₂ systems, both excitons confined in the Si well and excitons localized at the Si-SiO₂ interface determine PL properties. The electronic structures and luminescence properties of Si nanostructures are discussed.

An analysis is made of the ionization of deep impurity centers induced by high-intensity terahertz radiation whose photon energies are tens of times lower than the impurity ionization energy. Under these conditions, ionization can be described as phonon-assisted tunneling in which carrier emission is accompanied by defect tunneling in configuration space and electron tunneling in the electric field of the radiation. At high intensities the ionization is caused by direct tunneling. Within a broad range of intensity, frequency and temperature, the terahertz electric field of the radiation acts like a static field. For very high frequencies and low temperatures an enhancement in tunneling as compared to static fields takes place. Phonon assisted tunneling in high frequency as well as static electric fields is suggested as a method for the characterization of deep impurities in semiconductors. It is shown that an analysis of the field and temperature dependences of the ionization probability allows to obtain defect parameters like tunneling times, the Huang-Rhys factor as well as the basic structure of the defect adiabatic potentials.

A possible mechanism for the photoemission from Si nanocrystals in an amorphous SiO₂ matrix fabricated by ion implantation is reported. We have measured the implantation dose and the temperature dependence as well as the oxidation effect of the photoluminescence behavior of Si nanocrystals in SiO₂ layers fabricated by ion implantation and a subsequent annealing step. After annealing, a photoluminescence band, peaking just below the 1.7 eV was observed. The peak energy of the photoluminescence was found to be affected by the dose of implanted Si ions and the temperature during ion implantation, but to be independent of annealing time and excitation photon energy. We also present experimental results of an oxidation induced continuous peak energy shift of the photoluminescence peak up to around 1.8 eV. This peak energy, however, was found to return to its previous position with re-annealing. These results indicate that whilst the excitation photons are absorbed by Si nanocrystals, the emission is not simply due to electron-hole recombination inside the Si nanocrystals, but is related to the presence of defects, most likely located at the interface between the Si nanocrystals and the SiO₂, for which the characteristic energy levels are affected by cluster-cluster interactions or the roughness of the interface.

Ceramic samples SiC and AlN as well as SiC samples with different quantity of AlN admixtures was studied by infrared reflection spectroscopy and spectroellipsometry. The numerical modeling of optical properties of ceramic materials SiC+AlN type was made by using Bruggeman theory. Comparison of experimental spectra of refractive index and extinction coefficient for two-phases samples of SiC+AlN type with theoretical calculated give us possibility to make conclude that the system SiC+AlN is heterophase eutectic mechanical mixtures big clusters which are equal distribute in the space of the sample.

Presented work reports the results of luminescence investigation of thermal treatment influence on the spectral properties of sulphate crystals. The alkali sulphate polycrystalline samples, obtained after annealing and melting, reveal significant photoluminescence, that is not practically observed at the similar conditions for the respective single crystals. Besides, luminescence character depends on the thermal treatment conditions. Changes in the concentration of various type of defects in crystal matrix must be expected under annealing of sulphate crystals at the certain temperatures. Increasing of concentration of some defects creates possibility to their observation by luminescence method. We have investigated absorption, excitation, photo- and x-ray luminescence spectra of alkali sulphate single crystals and powders.

The angular dependences of color values for Al, Au and Cu samples with slightly rough surfaces were studied by numerical modeling. The surface polariton excitation was taken into account. The results were compared with color values for smooth surfaces.

A bond-conversion model for the photostructural changes in the photoluminescence and Raman spectra is proposed. The essential role in this model belongs to lone-pair electrons of chalcogen atoms, which are optically convert into bonding ones, leading to the structure reconstruction.

The present paper is concerned with investigations of photosensitive properties of As-S thin layers. Spectral dependence of the refraction index n of variously treated (virgin, exposed, annealed) samples was estimated from optical transmission in the spectral region 400 - 2500 nm. The n energy dependence of variously treated samples was fitted by the Wemple-DiDomenico dispersion relationship and used to estimate the single-oscillator model parameters. It was found, that exposure, as well as annealing leads to the increase in n values over the all investigated spectral region. Compositional dependencies of single-oscillator model parameter E_d (dispersion energy), optical dielectric constant ε(0) show maximum at stoichiometric composition As₄₀-S₆₀ and, possibly, weak maximum at As_28.6S_71.4 composition. Composition evolution of the intensity of bands in Raman spectra corresponding to the As rich and S rich molecular fragments is in agreement with compositional changes of E_d and optical dielectric constant. Changes of the parameters of the single-oscillator model induced by treatment are discussed on the base of photo- and thermally-induced structural changes and are consistent with topological models and models that claim a degree of chemical ordering. Such photoinduced structural changes provide good etching selectivity of As-S layers in amine based solvents. Surface relief patterns that were fabricated have good surface quality. Diffraction efficiency values of holographic diffraction gratings obtained on the base of As_100-XS_X layers consisted 60 - 70%.

The peculiarities of the exchange interaction between the carrier spin and localized spin moments of magnetic ions in narrow-gap quaternary solid solutions Hg_1-x-yCd_xMn_yTe and Hg _1-x-yCd_xMn_ySe are studied by means of photoluminescence in magnetic field and magneto transport (Shubnikov-de Haas oscillations). It is shown that the s-p hybridization of electron wavefunctions leads to the violation of the conventional selection rules, and the spin-flip processes contribute both in the optical and in the electrical phenomena. The exchange constant α turns out in a complicated fuction α of energy gap E_g and electron concentration which changes from positive α N_o = 0.15 eV to negative α N_o = -0.28 eV values which are typically accepted for wide gap semimagnetic semiconductors.

This article describes the charge injection into porous silicon structures fabricated by electrochemical technique on 20 Ohm cm p-type silicon. The I-V characteristics, photoluminescence spectra and lifetime kinetics studied at temperatures 77 K, 293 K and 373 K. Measurements show that the photoluminescence in porous silicon layers results from the recombination of electrons and holes captured in the potential wells of various depth and shapes; its intensity is controlled by the nonradiative recombination on the wires boundaries. The charge flow in the system Au(Al)-porSi-Si-Al results from the charge transfer in the system metal -- thin insulator -- semiconductor. The current is not restricted by the conductivity of insulating layers; it is restricted by the generation processes in the regions of space charge and semiconductor/insulator interface due to large amount of defects with various ionization energies. Potential barriers on the surface of porous silicon are formed due to surface defects on the interface silicon wire/oxide; their generation tends to shift the surface potential to the intrinsic value.

The optical transmission spectra of the thin Ge_xAs_ySe_100-x-y (0≤ x ≤ 30, 10 ≤ y ≤ 40) films and of two-layer systems on their basis have been studied. Changes of optical parameters (refractive index of films and photosensitivity, contrast coefficient of two-layer systems) induced by laser irradiation on the average coordination number ⟨m⟩ are discussed.

The effects of high-dose metal ion implantation on optical properties of metal mirrors have been analyzed by means of the IR Fourier transform spectral ellipsometry in the wavelength range 2 - 25 micrometer. The samples of polycrystalline Ti and Mo after the treatment by mixed ion beam of Ti⁺ and C⁺ were studied. In effective medium approximation the optical constants n and k as well as a complex dielectric function were calculated and their spectral dependencies for implanted surfaces were studied in comparison with non implanted. Optical properties changes were more essential for bombarded Ti surfaces than for Mo. Modification of Ti by the ions leads to entirely different from the Drude-like behavior of the complex dielectric function while in case of Mo it remains Drude-like. These changes could be associated with more significant disordering effects in case of Ti surfaces treatment by Ti⁺ and C⁺ ions than in case of Mo implantation by the same ions.

In the given work the rough surface of semiconductor is modeling by 2D fractal Wierstrass function. On the basis of the Kirchhoff scalar theory the scattering indicatrices for the some types od scattering surfaces are present. On the basis of numerical accounts average scattering coefficient the diagrams of dependence for various fractal semiconductor surfaces was constructed.

The effect of electron (E = 1.8 MeV), γ-(⁶⁰Co) and X-ray irradiation on the structural and optical properties of a (Ga,Al)As and a (Zn,Cd)Te quantum wells (QWs) grown on semi-insulating (SI) GaAs is studied. The high radiation hardness of the A3B5 QWs (no changes in recombination characteristics) after irradiation up to a dose of approximately 2•10⁹ rad was found, while SI GaAs substrate manifested the standard effect of the charge carrier removal under such irradiation dose. A2B6 quantum-sized structures (QSS) tends to degrade under lower irradiation dose. The emission bands transformation after irradiation up to a dose ≥ 2•10⁹ rad have been observed in ZnTe buffer layer and CdZnTe QWs. The role of Cd diffusion and internal strain in radiation enhanced ternary alloys QW's degradation is discussed. The calculation of PL peak energy shift is presented in assumption of the well profile change as a result of the radiation enhanced Cd diffusion.

The refined results of the specified dispersion of refractive indexes, birefringence,optical activity of anisotropic β-CdP₂ single crystals and the components of both the gyration tensor G₃₃ and the optical activity tensor γ₁₂₃ in a wide spectral band of polarized light under normal conditions are presented. The influence of temperature and radiation intensity of neodymium and ruby lasers on these characteristics of CdP₂ single crystals is studied and analyzed.

The detailed microstructural characterization of CuInS₂ (CIS) polycrystalline films is performed by combined in depth MicroRaman scattering/Auger Electron Spectroscopy measurements as a function of the chemical composition and temperature of processing. This has allowed to identify the main secondary phases in the layers as CuIn₅S₈ for Cu-poor samples and CuS for Cu-rich ones. The presence of such phases is strongly related to the temperature of processing, being secondary phase formation inhibited when the growing temperature decreases from 520°C to 370°C. This is also accompanied by a significant degradation of the structural CIS features, as reflected by the increase in both shift and broadening of the A₁ CIS mode in the spectra, and by the decrease of the grain size estimated by cross-section TEM. Besides, Raman spectra measured from samples grown at lower temperatures are characterized by the presence of an additional mode at about 305 cm^-1. The presence of this mode in the spectra from Cu-rich samples gives experimental support to its previously proposed structural origin. Finally, MoS₂ secondary phase has also been identified at the CIS/Mo interface region, being its occurrence also inhibited at low growing temperatures.

Development of nonlinear refraction diagnostics methods based on spatial beam distortions technique and nonlinear absorption measurements is illustrated with wide-gap semiconductors experimental data. With picosecond Z-scan technique we have studied competitive optical nonlinearities -- intraband direct equilibrium carriers transitions saturation and interband two-photon absorption (TPA) for a α-SiC(6H) crystal, and enhanced state absorption, absorption saturation and TPA -- of epoxy polymer based on diglicidyl ether of bisphenol A in a wide pumping intensities range (10 MW/cm² - 20 GW/cm²) at 532 nm. The complexity of the analysis was dealt with the nonlinearities signatures recognition problem and selection the part of the Z-scan curve which corresponds to the dominant contribution of the proper nonlinear mechanism on the background of competitive others. The TPA coefficient is β = 3.2 ± 0.3 cm/GW for the α-SiC(6H) crystal. The TPA coefficient is β = 4.0 ± 0.5 cm/GW for the polymer. At very high laser intensities (>7 GW/cm²) photoinduced transformation into some new configuration is taken place that is more absorbent at 532 nm. The TPA coefficient is β = 16.7 ± 3 cm/GW for the photoproduct. Up to pumping irradiance of 20 GW/cm² no optical damage of the polymer was observed.

Pseudomorphic strained-layer Al_xGa_1-xAs/In_yGa_1-yAs/GaAs heterostructures have been studied by means of photoluminescence (PL) and Raman scattering. It is established the correlation between the PL line shape changes and the Raman spectra modification when the QW width is below the critical layer thickness (CLT) estimated to be of 25 nm for y = 0.1. The PL feature observed for the InGaAs QW width equal to 20 nm as extremely narrow exciton-like peak with the FWHM equal 1.5 meV at low temperature (T = 6K) transforms into broad band of the FWHM equal 16 meV when the QW width reaches the value about of 12 nm. The PL line shape broadening is accompanied by the modifications of Raman spectra. A new line arising at the spectral position v = 160 cm^-1 is assigned to impurity-induced longitudinal acoustic optical mode of In_yGa_1-yAs. The changes observed in optical spectra are related to generation of defects in the under-CLT region.

Laser induced transient gratings are used to study carrier generation and recombination properties via free carrier nonlinearity in differently grown GaAs and CdZnTe samples. Simulation of free carrier, photorefractive, and absorptive optical nonlinearities for 10-ns pulses and various illumination intensities allowed us to reveal conditions for the efficient transient quenching of EL2 defect at room temperature in semi-insulating GaAs. In addition, the straightforward coupling of nonlinear degenerate four wave-mixing signal at 1.06 μm with the steady-state charge states of EL2 defect is shown to allow a rough estimation of a crystal compensation ratio by EL2 defect. This novel method was applied to liquid-encapsulated Czochralski and Bridgeman-grown samples and compensation values ranging from 0.1 to approximately 0.6 have been derived. Also, feasibility of nanosecond- and picosecond-dynamic grating techniques for control of GaAs wafer quality is shown. The first one allowed fast and highly sensitive mapping of EL2 defect distribution and its charge state; the second one has proved a presence of a fast traps in the vicinity of dislocation conglomerations. Analogous mapping of CdZnTe wafers has shown very high spatial homogeneity of the samples, and revealed areas with the non-photoactive absorption or scattering of light.

A number of methods for minimum registered quantity of photons scattered by the microparticles during its passing through the liquid medium are described. The configuration of photomultiplier amplifier to photon counting regime are described. Suggested amplifier for photon counting allowing the detection pulses with amplitude 50 mV and duration 3 msec passing boundary of the frequency band of the amplifier exceeds 100 MHz.

We describe a method for determination of the optical constants the refractive index n and the extinction coefficient k of thin films on relatively thick transparent substrate from measurements, at normal incidence, of reflectance R and transmittance T. The derivative is complicated by the existence of multiple solutions of the equations relating the above measurements to n and k. Another complication comes from the effects of multiple reflection in the substrate leading to the channelled spectra. The thicker the substrate the smaller the distance in spectra is between the interference maxima (minima). A frequently occurring situation is that the measurements of R and T do not exhibit a channelled spectra appearance because the measuring instruments do not have sufficient spectral resolution and/or because the interfaces and surfaces of substrate are not ideal, parallel. We present the formulae for the reflectance and transmittance for the system thin-film on substrate which reflect these experimental conditions. This allows to simplify the algorithm of calculation of the optical constants. The method is applied to the semiconducting thin film of β-FeSi₂ on silicon substrate.

In many optical applications of crystals birefringence dispersion seems to play an equal role to birefringence spatial inhomogeneity itself. Mapping of parameters associated with birefringence dispersion on the entire areas of wafers cut out from crystalline boules seems then to be a powerful tool in testing and research works dealing with optical materials. The method of birefringence dispersion mapping and an automated, computer-controlled spectropolarimeter have been described. Its working has been illustrated by birefringence dispersion mapping in gamma irradiated LiNbO₃ wafers.

In the present paper a comparative spectral study -- steady state and time-resolved photoluminescence (PhL) and radioluminescence (RL) -- of Eu-doped phosphors in different host lattices: BaFCl;Sr₃(PO₄)₂; Y₂O₂S;Y₂O₃ is reported. Steady state and time-resolved (induced by X-Ray tube, N2-laser and high-energy accelerated electrons respectively) PhL and RL measurements were performed. Bright mono-band and fine-structure line emissions in the blue-green and orange-red region were recorded in PhL and RL for all phosphors. The spectroscopic investigation permits the following conclusions: (i) The spectral patterns, decay curves and life-times observed in both PhL and RL are basically the same for all phosphors. On these observations it was assumed that similar luminescent species are involved in the both PhL and RL processes namely: mono-species Eu²⁺ and Eu³⁺ and their clusters (ii) Strong host-lattice influence on the status of Eu in the samples under consideration reflected in the spectral pattern, life-time and quantum efficiency was revealed.

This paper explores the use of a novel monitoring method in the manufacture process of optical microelements by means of controlled heating with laser. With this method, based on photoelasticity techniques, it is possible to display the mechanical stresses that forms the microelement and its optical properties. It is defined a new parameter, Relative Stress Area (RSA), which quantify the mechanical stress of a microelement during its creation process, make the comparison between different microelements possible. Also permits to display and quantify the three stages in the fabrication process: creation, balance and cooling. Different microlenses has been monitored and the results are presented in same images and graphs.

A Holographic Thermoplastic Interferometer for non-destructive testing (NDT) of materials and details developed by Tavex America, Inc. and its application are described. The interferometer is based on real-time holographic thermoplastic camera TCC-2 designed for multiple reversible registration of various types of surface relief phase holograms using thermoplastic film on glass substrate. The camera automatically monitors exposure and development. The Interferometer incorporates 5 mW He-Ne laser and complete optical set-up for easy-to-use operation even in daylight environment. The Interferometer is compact and has light weight.

The copper-doped lithium tetraborate Li₂B₄O₇ (LBO) is one of the promising materials for the thermoluminescent dosimetry since it possesses the best tissue-equivalence among known non-organic materials used in the dosimetry. In addition, this material has high radiation resistance, a linear dose dependence, a wide range of operating doses and an insignificant dependence of a dose on the ionizing radiation energy. However, the results of the studies on the local attachment level parameters, which define the dosimetric properties of Li₂B₄O₇:Cu, obtained by various authors differ considerably. To some extent, this descrepancies are due to the different purity of the initial materials and the technology of luminophor preparation, the methods of measuring the thermostimulated luminescence (TSL) and determining the parameters from the temperature luminescence glow curves (TLGC). In the present paper, the studies of the integral TSL in the polycristalline and monocrystalline LBO have been carried out at different heating rates. By means of a partial luminescence overall light collection method the energy positions of the local attachment levels have been determined, while the TLGC computer simulation technique has allowed the corresponding frequency factors to be found.

Recently a special attention is being paid to the studies of the proper and radiation-induced defects in the α-Al₂O₃ single crystals widely used in optoelectronics, laser technology and dosimetry. This is due to the fact that even in the nominally pure α-Al₂O₃ single crystal the structural defect concentration depends, to a considerable extent, on the initial burden quality, growing method and heat processing conditions. Depending on these factors, a series of crystal properties change essentially, especially the thermostimulated luminescence (TSL) and the X-ray luminescence (XL). The TSL intensity accumulated due to the isodose irradiation may serve the crystal defection criterion. In the present work, the integral TSL and the XL spectra of the nominally pure and doped α-Al₂O₃ single crystals produced by the GOI technique have been studied.

It is theoretically known, that there exists a reciprocal correspondence between Mueller and Jones matrix formalisms for deterministic objects. However, in practice, it is mostly failed to determine a Jones matrix corresponding an experimental Mueller matrix of the deterministic object. The reason of such situation is a presence of experimental errors of Mueller matrix measurements. In essence, there is no the systematic study of measurement error influence on results of analysis of information containing in Mueller matrix in polarization literature existed now. In the paper the method of finding of a deterministic Mueller matrix closest (the difference between its element values do not exceed a value of average measurement error) in some sense to initial experimental one is offered and for which the correspondent Jones matrix could be found. Our choice for the deterministic Mueller matrix is based on four anisotropy mechanisms: linear and circular amplitude (dichroism) anisotropy and linear and circular phase (birefrigent) anisotropy.

It is proposed and investigated the new scheme of holographic associative processor. The scheme provides the associative image reconstruction with almost the same intensity distribution as in an image in a non-diaphragmed initial transparency. The new photorefractive crystal Pb₅Ge₃O₁₁:Nd is used for image reconstruction by the proposed scheme.

The results of investigation of laser emission plasma exited by burst of laser pulses under normal atmospheric conditions are presented. It was showed that the spectra of laser emission plasma significantly depends on characteristics of laser burst. The proper choice of regime of laser source of excitation leads to increasing of signal to background ratio due to both spatial separation of area continuous radiation and area of linear spectrum and increasing of intensity of atomic lines. So the detection limit of trace element at laser induced breakdown spectroscopy (LIBS) may be improved essentially. The physical explanation is proposed.

The investigation of semiconductor GaAs/GaPAs heterostructures in wide spectral region from 0.3 to 70 μm were performed by excitation of interference modes. Such approach allows to avoid the ambiguity which arises at solving of inverse spectroscopic or ellipsometric problem. We propose to use the interference extremuma excited in the optical phonon region as a very sensitive to total thickness of heterostructure grown on doped substrate. The results show the interference method has a good sensitivity as well to chemical composition x of alloy as to geometrical parameters of corresponding films.