This PDF file contains the front matter associated with SPIE Proceedings Volume 7998, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

It is shown, that correct choice of complex forming ligand in the gel allows obtaining oriented ZnO films even on amorphous substrates. On crystalline substrates, in the case of small mismatches between lattice parameters of the substrate and the film, the main reason for the film orientation is epitaxial growth of ZnO film. In contrast to the case of liquid-phase epitaxy, the spontaneous polarization in epitaxial growth of lithium niobate films by the sol-gel method is directed normally from the substrate.

One of the promising ways to improve the efficiency of lasers operating at wavelengths near 1600 nm and 3000 nm on base of garnets doped with Er³⁺ ions is their sensitization with Ce3+ ions. In this work the investigation results of spectral characteristics of YAG:Er³⁺, YAG:Ce³⁺ and YAG:Ce³⁺, Er³⁺ crystals at room temperatures are presented. Dependencies of these characteristics on the optical excitations at 457 nm, 808 nm and 980 nm wavelengths are studied. The influence of Ce³⁺ sensitizer ions on the efficiency and mechanisms of the various energy levels' population processes of Er³⁺activator ions in the YAG matrix is discussed.

Thin films of Ga (0.9- 9.3 at.%) doped ZnO were prepared by e-beam evaporation in vacuum and their electronic and optical properties characterized using far-infrared reflectivity spectroscopy. The optical conductivity σ, dielectric ε and electron loss energy -Im(1/ε) functions of Ga doped ZnO films have been calculated via Kramers-Kronig transformation of the reflectivity spectra and analyzed by the generalized Drude (one-component) and Drude-Lorentz (two-component) models. Using Lorentzian oscillator to simulate the spectroscopic data it is revealed the presence of bound optically active electrons in mid-infrared 3500-4000 cm-1 range, whereas one-component Drude model shows frequency dependent scattering rate and enhanced low-frequency effective mass. Comparison carrier transport properties (charge concentration N, optical electron mobility μopt, and resistivity ρDr) derived from Drude analysis with those obtained by Hall measurements shows that the electron scattering from the grain boundaries makes significantly contribution to the electron mobility of ZnO films studied.

A parametrization scheme for the intensities of electric dipole parity-forbidden inter-Stark f-f transitions is proposed. This parametrization retains all the advantages of the widely used "approximate Judd-Ofelt theory" and at the same time, it takes into account the Stark structure of the optical spectrum of impurity ion, and so it is also applicable to the RE³⁺ ions (such as Ce³⁺ and Yb³⁺) with poor optical spectrum. Spectroscopic characteristics of YAG:Yb^{3 +} crystal due to inter-Stark transitions are calculated and quite satisfactory agreement with the experimental data is obtained.

The up-converted luminescence at 525, 550 nm and 670 nm wavelengths, as well as the ordinary luminescence near 1600 nm wavelength of the LiNbO₃:Yb³⁺, Er³⁺ crystal are investigated under optical excitations at 808 nm and 980 nm. Dependencies of luminescence on intensities of optical pumping at both wavelengths are presented. The possible mechanisms of up-converted emissions obtaining as well as population mechanisms of the Er³⁺ ion ⁴I_13/2 energy level in the LiNbO₃ matrix are discussed.

Based on the results obtained from detailed investigations of absorption and luminescence spectra of the LiNbO₃:Yb³⁺crystal the availability of this material for solid-state optical refrigerators is evaluated. Anti-Stokes luminescence registered for this crystal in the wavelength region near the 980 nm under the optical excitation at the 1064 nm allows estimation of main characteristics of the laser cooling effect. Conditions for increasing the efficiency of laser cooling effect in the material under study are discussed. The new approach to measure temperature changes of ferroelectric samples under an optical irradiation is proposed.

Photorefractive damage and photoconductivity in as-grown, reduced and oxidized iron doped lithium niobate (LiNbO₃, LN) crystals, in two series of samples with 0.03 and 0.05 wt% iron concentrations, respectively have been studied with the closed-aperture Z-scan technique. The photoconductivity in the various crystals was directly deduced from the dynamic distortion of the beam spot of a red laser light passing throughout the sample, placed at the focal point, followed by a pin-hole and recording in the far field zone behind the crystal. The most important experimental result points out a non-linear increase of the photoconductivity with the laser power density and with the iron concentration in the crystal. To explain these experimental findings, we use the theoretical model taking into account the photoionization of iron ions and intrinsic defects, namely polarons, bipolarons and hole polarons.

We present theoretical study of the third type thermomechanical effect in twist aligned nematic liquid crystal cell. Euler- Lagrange-Rayleigh variation method is applied together with the heat-transfer equation to analyze the laser-induced nonlinearity and director reorientation due to the third type thermomechanical effect. Director reorientation due to a transversal 2-dimensional temperature gradient is considered. Director equation is solved numerically and phase shift distribution is presented. It was explained that phase shift is zero in some areas because temperature gradient x and y components compete with each other to reorient the director in opposite directions. It was shown that maximum phase shift is at the same range as that for the Giant Optical Nonlinearity (GON).

We report the preparation and investigation of heterostructures based on ferroelectric crystals and semiconductor films. The ferroelectric field effect transistor with high transparency for visible light and high field mobility of the charge carriers has been fabricated using ZnO:Li films as a transistor channel. The possibility of use of ferroelectric field effect transistor based on ZnO:Li films as bistable element for information writing has been shown.

It is shown that the thermodynamic potential of the domain-like incommensurate (IC) phase of the K₂SeO₄crystal (viewed as a model for the IC-C transition) should be supplemented with a term, taking into account the local, Lorentz electric field. The latter qualitatively changes the result of calculation of the dielectric susceptibility for this IC structure by Nattermann and Trimper, J. Phys. C: Solid State Phys. 14, 1603, (1981), and gives phase transition to the ferroelectric IC phase obtained by Aslanyan, Phys. Rev. B 70, 024102, (2004).

Effect of the bottom electrode (LaB₆) on electron emission characteristics (current density, excited voltage), leakage current behavior and polarization-voltage hysteresis of the Ag/PbZr_0.52Ti_0.48O₃/LaB₆/Al₂O₃ capacitor has been firstly experimentally investigated by fabricating PbZr _0.52Ti_0.48O₃ (PZT) and LaB6 films with sol-gel and e-beam evaporation techniques respectively. The current-voltage (I-V) and hysteresis (P-E) characteristics show different charge distribution at the top and bottom interfaces. Leakage current behavior as a function of voltage is interpreted by Schottky charge transport mechanism. Electron emission from the PZT surface under low driving pulses <0.4 V has been detected in vacuum chamber with pressure 4x10^-5 Torr. Current densities in the range of 0-105 μA/cm² have been measured in a diode configuration under 10-22 kV/cm excitation voltages and compared with data reported in the literature.

We evaluate the prospects of cerium hexaboride (CeB₆) crystals for use as a sensitive element in so-called QVD thermoelectric single photon detectors, which operate at cryogenic temperatures. By gathering and analyzing the values of the thermoelectric parameters for CeB₆ reported in the literature up to this date, we have evaluated the promise of cerium hexaborides as a sensitive element in thermoelectric single photon detectors at temperatures above 4K. We have concluded that such detectors can detect a single UV photon, have very fast count rate (up to 100 MHz) and a spectral resolution of 12.7 eV. QVD detectors based on CeB₆ crystals, by virtue of operating at temperatures above 4 K, can have a wider field of application.

Crystals of solid solutions of lanthanum-cerium hexaborides (La_1-xCe_x)B₆ possess unique thermoelectric properties in the temperature range of 0.3-9 K and they can be used in thermoelectric single-photon detectors as a sensor. One can observe a wide spread in thermoelectric measurement values reported in the literature, which is because of different qualities of studied crystals. The greatest influence on both the Seebeck coefficient and electrical resistivity of samples is exercised by the presence of uncontrolled impurities in crystals and the deviation from stoichiometry. In this work we have studied just the aforementioned parameters of the crystals obtained by three different methods.

Among salts of amino acids there are compounds with the composition 2A..HX, which consist of dimeric A...A⁺ cations with short symmetric or asymmetric hydrogen bonds between zwitter-ionic and protonated moieties. These species are materials liable to undergo phase transitions or possess interesting nonlinear optical properties. Here, we report the preparation of 20 new salts with dimeric cations from aqueous solutions, including compounds of glycine, betaine, β- alanine, L-alanine, L-phenylalanine, L-threonine, L-valine, L-leucine and L-proline, with BF₄-, ClO₄-, Cl-, Br-, HSeO₃-, and HC₂O₄-; as anions. The prepared salts are characterized by IR and Raman spectroscopy. Some of them are grown in form of good quality single crystals, which allowed the determination of their crystal structure.

New crystalline salts of L-threonine, i.e. L-Thr.HCl, and L-Thr.HBr have been obtained from aqueous solution by slow evaporation technique. Infrared and Raman spectra of L-Thr.HCl and L-Thr.HBr were recorded and interpreted on the basis of crystal structure of L-Thr.HCl. The similarity of their IR and Raman spectra indicates similar structures. Nonlinear optical properties of the crystals were tested qualitatively by observation of second harmonic generation of Nd:YAG laser.

A new combined interferometric-mask method is suggested and realized for creation of 3-dimensional (3D) holographic periodic and quasi-periodic structures in photorefractive materials. The method is based on the preparation of 2- dimensional (2D) micrometric scale masks with different symmetries and illumination of the photorefractive material through the mask by Gaussian beam in combination with back reflecting mirror. The counter-propagating beam geometry builds up Gaussian standing wave, which determines the third half-wave period of the grating in the axial direction. Thus, the created 3D intensity pattern can be represented as numerous mask-generated 2D quasi-periodic structures located in each anti-node of the standing wave. The formed intensity pattern can be imparted into the photorefractive medium via electro-optic effect, thus creating micro- and sub-micro scale 3D refractive index volume gratings with new symmetries and properties. The gratings were recorded by 532 nm cw laser beams in Fe-doped lithium niobate crystals taking into account their high photorefractive properties and possibility of creating the persistent gratings. The gratings formed have ~ 10 μm period in radial and azimuthal directions and ~266 nm in axial direction. The gratings were interrogated by diffraction of low intensity Gaussian probe beams from the recorded structures.

Thermomechanical nonlinearity caused by transversal temperature gradient was experimentally investigated. Temperature dependence of this effect is investigated in twist aligned nematic liquid crystal cell (with thickness of 100μm). It is shown that the effect is orientational and non-diffractional. It is also shown that the orientational optical nonlinearity of revealed thermomechanical effect may be as strong as well-known giant optical nonlinearity. Besides, at normal incidence of the laser the giant optical nonlinearity does not exist, but thermomechanical effect exists at any angle of incidence of the laser and the nonlinearity of thermomechanical effect remains in the same order.

Photochromic effect of lithium nioabate crystal doubly doped with Fe and Cu (LN:Fe:Cu) was investigated for 532 nm wavelength illumination with the aim of nonvolatile holographic recording of 2-dimensional (2D) gratings. The investigation showed that the absorption coefficient of LN:Fe:Cu crystal was increased 1.6 times when the illumination intensity was increased from 12.5 mW/cm² to 96.8 mW/cm². LN:Fe:Cu crystal was further used for recording of 2D gratings by counter propagating Bessel beam holographic method using cw 532 nm laser beam with 17 mW radiation power. The holographic recording in phorochromic doubly doped LN crystals allowed the essential decrease of the erasure of the stored grating during readout by weaker probe beam at the recording wavelength. The observation showed that during illumination by weak 2mW probe beam the power of diffracted ring decreased to 12% of its original value after 5500 sec. The entire erasure of the stored grating occurred after 8000 sec illumination.

We investigate light wave propagation through a one-axis anisotropic medium layer with simultaneously non-unit dielectric and magnetic tensors. 4x4 - Δ^▵(see manuscript) matrix is built. We consider the general case when the dielectric and magnetic permittivity tensor elements have both positive and negative sings. We obtained the dispersion equation and then built dispersion surfaces for a homogeneous anisotropic uniaxial material when the material is negative or positive (both with respect to the wave vector and Pointing's vector orientation of the refracted wave; the sign of the material is accordingly defined below.) Electromagnetic plane waves propagating inside the medium can exhibit dispersion surfaces in the form of ellipsoids of revolution, hyperboloids of one sheet, or hyperboloids of two sheets. The conditions of negative refraction with respect to the wave vector and Pointing's vector orientation are considered. We found wave nonreciprocity for the oblique incidence on the considered system and we showed that such a system can work as an alloptical diode.

The reflection and transmission of electromagnetic waves in 1D photonic crystals (PCs) is discussed. The periodicities of both dielectric and magnetic permittivity are taken into account. The dielectric and magnetic permittivities are considered as spatially changing arbitrary functions. We show that for a certain, sufficiently large, range of cases this problem can be reduced to a set of two linear differential equations instead of complicated matrix equations of transfermatrix method. The effects of the Photonic Band Gap (PBG) shift, width change, new transmission zone contacts, etc., in cases of different PC apodization and chirp are investigated. This method works fine for standard PCs, as well as for left media and metamaterials. An important consequence is the condition for PBG suppression for all wavelengths, associated with non-constancy of both dielectric and magnetic permittivities.

The signal analysis-synthesis problems at a few femtosecond time scale demand the generation and study of broadband similaritons. We generate similariton of ~100 nm bandwidth and characterize it experimentally to reveal its nature and distinctive properties, and to describe it mathematically. We carry out the complete characterization of the broadband similariton by means of its chirp measurement through the technique of spectral compression and frequency tuning in the sum-frequency generation process. Our studies are of interest in view of applications of similariton to the solution of signal analysis and synthesis problems in ultrafast optics, particularly for similariton-induced temporal lensing and similariton-based spectral interferometry. Our developed method of similariton chirp measurement can also serve for the fiber characterization.

We demonstrate pulse compression by generating nonlinear-dispersive similariton in fiber and its chirp cancellation in a dispersive delay line, consisting of a pair of fused-silica dispersive prisms. The initial pulse with 11 nm bandwidth and 146 fs autocorrelation duration was used to form the similaritons with different bandwidths. We have synthesized approximately transform-limited pulses of down to 25 fs autocorrelation duration, i.e. ≈ 17 fs duration, from a similariton of 77 nm bandwidth. All obtained results are in a good agreement with the numerical simulations.

Intense, well-controlled regular light pulse trains start to play a crucial role in many fields of physics. We theoretically demonstrate a very simple and robust technique for generating such periodic ultrashort pulses from a continuous probe wave which propagates in a dispersive thermal gas media.

A new microwave-exciting scheme useful for gas laser, especially for CO2 slab lasers is offered. A lumped circuit resonator like loop-gap resonator gives opportunity to get extremely homogeneous electromagnetic field and therefore a homogeneous discharge for gas laser application, narrow discharge gap and easy matching a microwave source and resonator. The some physical and the associated technical problems of the transverse microwave discharge for an excitation of diffusion cooled gas laser are discussed.

We present the results of numerical study of the generation process of difference frequency radiation (DFR) arising via interaction of mutually orthogonal linearly- polarized a few-cycle laser pulses propagating in a quasiphase- matching (QPM) GaAs crystal. Considered the interaction of pulses having the central wavelengths of 1.98 μm, duration of 30 fs with the electric field amplitude 200 MV/m, propagating along the normal to the <110> plane. The period © of QPM GaAs crystal in numerical simulations varied from 20.89 μm to 53.23 μm. It is shown that by changing the grating period of QPM GaAs crystal from 23.02 μm to 37.29 μm it's possible to improve efficiency of QPM generation of DFR in 5.48 μm ÷ 10.12 μm spectral range at least by 8 dB in comparison with the generation of DFR in bulk crystal GaAs in the same spectral range.

In this work we presented the results of numerical analysis of higher order nonlinear Schrodinger equation (NLSE) performed by the method of lines (MOL). In the higher order NLSE we take into account the imaginary Raman term. It is studied the impact of the dissipative Raman term on the femtosecond first order soliton stability. According to the results of numerical simulations, when real part of Raman term is equal to zero in the wavelength range, where second and third order dispersion negative, there exist analytic solitary-wave solutions. Our numerical simulations closely follow the published analytical data.

Interaction of alkali atoms with external magnetic field induced a splitting and a shift of their energy levels. We have studied this interaction for external field from 0 to 5000 Gauss when the alkali vapor is confined in submicron thin vapor cell with thickness L = λ /2. Rubidium and Sodium vapors have been studied. The Hamiltonian can be expressed as the sum of the unperturbated atomic Hamiltonian and the so-called Zeeman Hamiltonian. The probability of a transition, induced by the laser electric field is proportional to the square of the transfer coefficients modified by the presence of the magnetic field. We will show that the strong nonlinearity of the transition intensities versus the external magnetic field intensity is obvious for B > 100 G. Some possible applications for Laser Spectroscopy of the Rb and the Na atoms are presented.

We study the dynamics of cold molecule formation via photo- or magneto-association of quantum degenerate atomic gases for the case when the field configuration is defined by the quasi-linear level crossing Demkov-Kunike model, which is characterized by a bell-shaped pulse and finite variation of the frequency detuning. We generalize the approach developed for the Landau-Zener model and propose a cubic polynomial equation for the asymptotic transition probability at t → + ∞ applicable in the large detuning regime of the interaction process. The proposed approximation applies to all values of the Rabi frequency; hence, it presents a unified description of previously noticed weak, moderate, and strong interaction limits of the fast sweep regime. This cubic equation for the transition probability provides improvement of previous results by an order of the magnitude.

We report the preliminary results of experimental studies of a dense cesium vapor in all-sapphire sealed-off Cs cell (temperature up to 500 °C, atomic and molecular densities up to 10¹⁸ and 3.2x10¹⁶ cm^-3, respectively) in selective reflection (SR) configuration. Probing the vapor by a 780 nm laser radiation scanned in 20 GHz range, we have observed a spectral structure, which appears in the vapor temperature range of 250 - 400 °C. Though the cell is filled with pure cesium, starting from 300 °C we have revealed a noticeable SR contribution of rubidium atomic D2 line transitions that fall in the laser tuning range. The spectral features observed in present work can be attributed not only to cesium dimers (Cs₂) having absorption band in this spectral region, but also to RbCs molecules. Relevant spectroscopic properties of these molecules are also addressed. We believe this is the first observation of selective reflection from the interface of dielectric and molecular vapor. More experiments and theoretical treatment is required to clarify the mechanisms involved and identify the origin of each spectral component, the further work program is outlined.

The so-called "λ/2-Zeeman technique" (HLZT) for studies of individual optical transition between Zeeman sublevels of atomic hyperfine structure in an external magnetic field of B = 10 - 2500 G is presented. Particularly, implementation of HLZT allows one to realize a direct determination of frequency shift and a strong modification of an optical transition probability between Zeeman components in a B-field. The main advantages of the method compared to "λ-Zeeman technique" (LZT) is that it allows one to study weak transitions. Particularly, with the help of fluorescence on 87Rb, D2 line, F_g = 1 → Fe = 3 transitions, three "forbidden" transitions in magnetic field B are detected and studied. Also, on 87Rb D1 line, F_g = 1, mF = 0 → Fe = 1, mF = 0 "forbidden" transition is detected when B ~ 400 G. A strong modification of the probability for these "forbidden" transitions is revealed. The theoretical model well describes the observed results.

We consider an atomic dual Λ-system under two-laser-field excitation to investigate the possibility of indirect coherent transfer of population between atomic ground states through an excited state. The atomic system, namely atomic vapor in a buffered cell, is excited by a frequency modulated pump laser and probed by a low-power cw laser. The study can be helpful to understand the mechanisms of collisional coherent transfer of population and other related phenomena and applications.

The effect of self-induced transparency (SIT) for probe field in the N-type atoms is predicted. The two ground states of atoms are coupled via two photon Raman transitions by means of probe and driving fields, which are strongly detuned from one photon resonance, while the probe field is also resonantly connected to third optical transition from the second ground state. It is found that the probe absorption features the Doppler profile in dependence on Raman detuning δ with a narrow deep for small values of δ. However, in the vicinity of δ=0, an ultra-narrow EIT resonance with subnatural width is observed caused by the probe field itself. The effect is explored analytically and numerically. A scheme is elaborated to demonstrate the SIT experimentally in the alkali vapors at room temperatures.

Collisions of atoms with formation of Feshbach resonances in the presence of laser field are considered. The elastic and inelastic scattering cross sections are calculated. The laser field leads to second resonance in elastic scattering, broadening of resonances, and arising of interference between resonant and potential scattering. The effects associated with interference of the two channels of decay of bound system of two atoms (a molecule) in laser field are studied. It is shown that if the energy equals that of the lower stable Stark-shifted level plus the energy of two photons, the resonance is quenched. It is also shown that with the increase in two-photon effective interaction the pattern of resonance scattering changes essentially.

Possibility of coherent control of spontaneous emission from four- and five-level systems in the laser radiation field is studied. The four-level system consists of two levels resonantly driven by laser radiation where either of levels may decay to a separate level. For such a system we show that the presence of the second decay channel may deteriorate the destructive interference occurring because of Autler-Townes effect in case of one decay channel. The five-level system represents two two-level resonantly driven systems with the upper levels decaying to a common level. For this case, the interference between the two decay channels is partially or completely destructive or constructive depending on the initial conditions and on the mutual orientation of the transition dipole moments. It is shown that population transfer takes place by the same quantum vacuum via spontaneous emission. The populations are shown to have damping oscillatory nature.

The problem of Kapitza-Dirac diffraction is solved in the Raman-Nath approximation without limitations on resonance detuning. A formula for the scattering amplitude in a definite integral form is obtained. It shows that in the case of initial superposition state of discrete Gaussian form the scattering spectrum has a new regularity, more usable for atomic optics.

The aim of the illustrated work is the experimental investigation of displacement of wavelength of the coherent radiation passing through polarization interferometer. Accuracy of the measurement of displacement of wavelength reaches to 1·10-2 nm.

The influence of laser radiation is one of the means of changing the microstructure, physical properties of solids and stabilizing metastable states. In this work we investigate the influence of laser radiation on surface morphology, composition and electrical conduction of copper oxide ceramic samples. The samples were synthesized under different conditions; part of them was covered by copper film and subjected to additional thermal treatment. The laser processing of crystal surfaces was carried out by the radiation by the second and third harmonics of a YAG:Nd laser. We have studied the temperature dependence of resistivity and the volt-ampere characteristics of the samples within the 77-300 K temperature range. In some of the samples we have observed HTSC-like drop of resistivity at ≤ 250 K temperatures.

Electrical characteristics of DLC- (n, p)-Si heterojunctions fabricated by ion-assisted plasma-enhanced deposition and pulsed laser deposition methods were investigated. The mechanisms of carrier flow across the fabricated junctions were analyzed. Keywords: ion-assisted plasma-enhanced deposition, pulsed laser deposition, DLC- (n, p)-Si heterojunctions, currentvoltage & capacitance- voltage characteristics.

The key problems of optical transmission imaging of thick complex biological objects are strong diffusion (scattering) and non-uniform intensity distribution of transmitted signal across the scanned area. These constraints essentially reduce the spatial resolution and uniformity of the overall pattern. We report on implementation of a new approach of signal detection scheme, which relies on synchronization of lock-in amplifier with a temporal step of laser beam discrete scanning. This technique is favorable for preferential detection of abrupt spatial features, increase of contrast and substantial reduction of overall non-uniformity of image brightness. On the other hand, the lock-in detection scheme, being phase-sensitive, helps to some extent to enhance the contribution of least-deflected photons in the recorded signal thus suppressing the diffusion component. We present the results of measurements showing efficiency of the proposed scheme.

A new method of preparing a single photon in temporally delocalized entangled modes is proposed and analyzed. We show that in a medium of four-level atoms with tripod-level configuration a strong parametric interaction between two one-photon pulses emerges, if the medium was initially prepared in a coherent superposition of the two ground states, while a strong classical field drives the neighbor transition from the third ground state. The analytical solution of Maxwell equations reveals that under the electromagnetically induced transparency (EIT), the quantum fields propagate with significantly small absorption and with different group velocities that leads to their temporal split into well-separated pulses, the amplitudes of which are well controlled by the driving field. The proposed scheme can serve as a robust source of narrow-band one-photon qubits with an entanglement between two temporal modes, not sensitive to losses in atmosphere and in telecommunication waveguides. We show also that in our scheme a controllable degree of temporal entanglement can be achieved.

We investigate production of three-photon and four-photon states in cascaded parametric processes of photon splitting and summing in χ ⁽²⁾nonlinear media, under action of pump field. Generation of photon triplets using simultaneously phase matched three-photon processes: ω₀↔ω₁+ω₂ , ω₂↔ω₁+ω₁ , is considered in dual-grating layered structure that involves nonlinear and linear segments. The production of heralded two-photon entangled states from three-photon states is analyzed for this configuration by using the method of conditional detection of auxiliary photons. Cascaded four-photon downconversion based on simultaneously phase matched three-photon processes: ω₀↔ω₂ +ω₂ , ω₂↔ω₁+ω₁ is arranged for phase-reversed configuration. The effects of correlation between photons in both three-photon and four-photon states is analyzed in the regimes of amplification of corresponding modes at the frequency of three-photon downconversion ω₁ = ω₀/3 and the frequency of four-photon down-conversion ω₁ = ω₀/4respectively for both cascaded systems.

Recently, superconducting artificial atom has been justified experimentally as an ideal element for various applications including circuit quantum electrodynamics realizing strong-coupling limit. Some of the proposed systems in this area are usually described in terms of the quantum anharmonic oscillator and display quantum dynamics in macroscopic level, giant nonlinearity as well as very strong coupling with external field and strong coupling with an environment. In this report, we investigate the quantum properties of an artificial atom as a model of multilevel anharmonic oscillator in the framework of photon number distributions as well as the Wigner functions. We concentrate on the regimes of strong driving and giant nonlinearity that allow us to consider artificial atom on the level of few excitation numbers.

Deflection of an atomic beam passing through two crossed standing light waves is proposed for studies of transition through the Raman resonance in Λ -atomic systems. Considering different regimes of excitation of Λ -atoms by offresonant standing waves, we demonstrate that the deflection patterns, in the plane perpendicular to the direction of the center of atomic mass motion, are essentially different for the cases of one-photon and two-photon excitations. Visualization of the quantum superposition states of low atomic levels on the two-dimensional spatial patterns of atomic deflection is performed.

We investigate specific features of the dispersive vacuum polarization effects for the light propagation in magnetized vacuum which are induced due to spatial modulation of the magnetic field. The reciprocal lattice vectors associated with the periodic field are involved in the energy-momentum conservation for the photon interaction processes which allow elastic scattering of impinging photons by a strong magnetic field. The efficiency of the scattering is shown to be coherently enhanced due to interference of the scattered waves from the periodic structure.

We propose and analyze a scheme for creation of coherent superposition of meta-stable states in a multilevel atom. The scheme is based on interaction of a frequency modulated (chirped) laser pulse and a pulse of a constant carrier frequency with the atom having two meta-stable (ground) states and multiple excited states. The negligible excitation of the atoms is a priority in the proposed scheme to eliminate the de-coherence processes caused by the decay of the excited states. The scheme is applied to create coherent superposition of magnetic sublevels of ground states of the ⁸⁷Rb atom taking into account all allowed electric-dipole transitions between magnetic sublevels of the 5 ²S_1/2 - 5²P_3/2 transition (D₂ line). In addition to the theoretical analysis we consider possible experimental realizations of the proposed coherence creation scheme and discuss their feasibilities and constraints. We concentrate on a detection of the superposition state in the Faraday-rotation experiment. Such detection reduces technical laser noise background and offers high sensitivity of the coherence detection. Moreover, it allows extra control of the atomic sample and the interaction dynamics by external magnetic field.

By using the solid-phase pyrolysis of phthalocyanines the nickel-carbon nanocomposites have been synthesized. The composition, structure, and morphology of samples were investigated by scanning electron microscopy and Raman spectroscopy. The first-order Raman shifts of prepared materials were measured with laser excitation at 514.5 nm in the frequency range from 900 to 2000 cm^-1. It is shown that the degree of graphitization in nanocomposites essentially depends on the pyrolysis temperature. By analyzing the intensity ratio of Raman D- and G-bands the mean sizes of graphitic nanocrystallites in prepared samples were estimated.

In this paper two electronic states in spherical quantum nanolayer are discussed. The Coulomb interaction between the electrons is discussed as perturbation. For confinement potential of the nanolayer the three-dimensional radial analog of Smorodinsky-Winternitz potential is considered. The problem is discussed within the frameworks of Russell-Saunders coupling scheme, thus, the spin-orbit interaction is considered weak. Therefore the eigenfunctions of the system is represented as a multiplication of its coordinate wave function and spin wave function. For this system the analogue of helium atom theory is represented. The eigenfunctions and energy states are obtained for one and two electron cases in the spherical quantum nanolayer. For the spherical nanolayer the dependence of perturbation energy, unperturbed system energy and the total energy for the ground state upon the inner radius is represented when the outer radius is fixed.

The spatial and time dependencies of the dielectric function for the quasi-two dimensional (Q2D) electron gas (EG) in a finite confining potential quantum well (QW) are calculated by using a self-consistent approach (SQF). Taking into account the influences of mismatch of strong discontinuous dielectric constant and effective masse across the interfaces the dielectric response function analytic expressions are derived for a rectangular finite potential barrier QW for the first time. The deviations from the results when these mismatches are absent are established. By using exactly calculated dielectric function a comparison with the respective asymptotic expressions of finite and infinite confining models is presented both analytically and numerically on the base of realistic EuS/PbS/EuS QW. The transition interval between 2D and 3D cases has been demonstrated numerically.

Recently a new approximate analytical method based on simple physical reasoning for the calculation of surface plasmon frequencies in the complexes of metallic nanoparticles (MNP) (particularly spheres) has been proposed [1]. The method called Eliminated Quadrupole Moment Approximation (EQMA) allows adequate description of existing experimental data concerning surface plasmons in the system of two coupled spheres [4]. We present the results of numerical simulation based on Discrete Dipole Approximation (DDA) ([5]) performed in order to identify the limits of applicability of EQMA. It is shown that EQMA works very well for interparticle distances down to 0.1 of the diameter of the sphere. It is demonstrated also that obtaining of reliable numerical results with use of DDSCAT (simulation tool for DDA, [7]) requires presentation of the spheres as an ensemble of more than 500000 point dipoles, whereas in EQMA each of the spheres is substituted by only one dipole. The obvious advantage of EQMA is that it provides the resonance frequency for the given values of the parameters of the problem practically instantly while the DDSCAT requires several hours to obtain the same result.

Within the framework of adiabatic approximation the energy levels and direct interband light absorption in a strongly prolated ellipsoidal quantum dot are studied. For treatment of the "slow" subsystem modified Pöschl-Teller effective potential is used. It is shown that the low-energy levels of the spectrum are equidistant. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in strong quantization regime are obtained. Selection rules for quantum transitions, absorption edge and absorption coefficient are revealed. Size dispersion distribution of quantum dots by the minor semiaxe by two experimentally realizing distribution, Lifshits-Slezov and Gaussian functions, have been taken into account.

Using the effective mass approximation and a variational procedure, we have calculated the effects of confining potential and growth-direction applied magnetic field on the binding energy and photoionization cross section of a donor impurity in a cylindrical InAs Pöschl-Teller quantum layer. We report the binding energy dependencies on the height and the inner and outer radii of the cylindrical layer, the applied magnetic field, and the parameters of the Pöschl-Teller confining potential. The dependencies of the impurity-related photoionization cross section on the incident photon energy for the different values of the confining potential parameters and the geometrical parameters of the heterostructure have been also considered. The results show that the impurity related binding and energy photoionization cross section are non monotonic functions of the inputs here considered. Particularly, it is shown that the binding energy increases with the increase inner radius of the layer and decrease with the all another inputs considered in this work (height and outer radius of the layer, applied magnetic field, and asymmetry of the Pöschl-Teller potential). In the case of the photoionization cross section the results show that with changes in the dimensions of the heterostructure and in the symmetry of the potential both blue shift and/or red shift of the maximum of the lineshape can be induced.

We investigate the optical bistability (OB) behavior in a unidirectional ring cavity containing an asymmetric semiconductor double quantum dot (QD) system that forms a three-level V type system. We apply a probe and a coupling field to the system and it is shown that in the presence of inter-dot tunneling, the bistability of the system can be controlled by amplitude and relative phase of applied fields.

We study the transient properties of phase and amplitude-controlled transparency in a three-level pump-probe quantum dot molecule. We apply a probe and a coupling fields to an asymmetric double quantum dot and we find that under transparency condition, system can exhibit transient gain without inversion. It is shown that dynamical behavior of absorption and gain are dependent to the relative phase of applied field as well as the parameters of the system.

This study aims to designing quantum dot semiconductor optical amplifier (QD-SOA) by amplification without inversion technique in In_xGa_1-xN/GaN semiconductor quantum dot (nanostructure). To do this, eigen energies and their corresponding wave functions of a Y-type four-level atomic system were obtained by solving of Schrodinger- Poisson equations self-consistently (considering intersublevel transitions) in In_xGa_1-xN/GaN quantum dot. The principle of quantum optics to obtain dynamic property of quantum dot density matrix elements was employed and investigated the lasing without inversion (LWI) phenomenon in this quantum dot.

Pr³⁺-doped Lu₃Al₅O₁₂ (LuAG:Pr) bulk single crystals were grown along the <100> direction by the vertical Bridgman method. The concentration distribution of Pr3+ over the crystal length was calculated and used to plot the dependence of the absorption coefficient at 582.3 nm (3H4 → ¹D₂) on the Pr3+ concentration. A concentration series of polycrystalline LuAG:Pr in the form of reacted powders was prepared under reducing atmosphere. Lattice parameters were measured in variously doped single crystals and reacted powders and used for estimation of the extent of non-equivalent substitutions by Lu³⁺ for Al³⁺ in octahedral lattice sites.