Interference phenomena lead to a wealth of applications in many areas of physics. Entangled quantum states allow one to surpass the classical measurement sensitivity or resolution in polarimetry, interferometry, and imaging. In this paper we shall review, in some depth, polarization properties of quantized two-mode electromagnetic fields and show how interference and quantum entanglement lead to new phenomena. We shall also briefly discuss subwavelength quantum lithography.

Quantum properties of the two-mode Kerr states such as squeezing, sub-Poissonian photon statistics, Schoedinger cats, quantum correlations between the modes, polarization and quantum depolarization as well as quantum noise in the Stokes parameters are reviewed. The role of dissipation is also discussed.

Different quantum information schemes, such as eavesdropping in quantum cryptography, dictate the necessity of extracting information about pair conjugate observables from a single copy of a quantum system. Mathematically, quantum measurements are usually described by an uncertainty relation. The difference between the simultaneous measurement uncertainty relation form those known from the textbooks on quantum mechanics is the additional uncertainty associated with the measurement procedure itself in contrast to the state preparation uncertainties described by the Schroedinger-Robertson type uncertainty relations. We present here an overview of our approach based on the state estimation theory and maximum likelihood strategy. We make a theoretical analysis and an experimental verification of minimum-uncertainty product of the two-states quantum system simultaneous measurement based on partially entangled photon pairs.

Using the formalism of the Stokes operators, a Wigner-type polarization quasi probability function and related tomography techniques, we analyze polarization properties of the XY-type biphoton light produced by a cw optical parametric oscillator. An appropriate data processing allowed to reveal experimentally the properties of hidden polarization and polarization squeezing for the parametric radiation, as well as to manifest a similarity between the calculated polarization Wigner function and that obtained via polarization tomography of the light produced.

It is shown that quantum tomography can detect and correct unlimited number of errors during the evaluation of quantum algorithms on quantum computer.

Relevance of key quantum information measures for analysis of quantum systems is discussed. It is argued that possible ways of measuring quantum information are based on compatibility/incompatibility of the quantum states of a quantum system, resulting in the coherent information and introduced her the compatible information measures, respectively. A sketch of an information optimization of a quantum experimental setup is proposed.

We explore the role played by the quantum relative phase in the well-known Dicke model. We introduce an appropriate polar decomposition of the atom-field relative amplitudes that leads to a truly Hermitian relative-phase operator, whose eigenstates correctly describe the phase properties. We find the probability distribution for this relative phase and, by resorting to a numerical procedure, we study its time evolution.

Starting form the first principles of nonrelativistic QED we have derived the system of Maxwell-Schrodinger equations, which can be used for theoretical description of atom optical phenomena at high densities of atoms and high intensities of the laser radiation. The role of multiple atomic transitions between ground and excited states in atom optics has been investigated. Nonlinear optical properties of interacting Bose gas are studied and formula for the refractive index has been derived.

The quantum theory of nonlinear dynamics and self-switching effect for two coupled bosonic modes in nonlinear spatially inhomogeneous system shave been developed using Hartree approximation for the first time. The quantum limits of observation of self-switching effect for the polarization characteristics have been founded. We also predict the formation of nonclassical mesoscopic states in such a system as well. We also propose four-mode interaction in the systems under consideration for quantum XOR and SWAP logic operations.

We study the coupled translational and internal dynamics of a two-level atom in a spatially periodic optical potential created by a single-mode field in a high-finesse Fabry-Perot cavity. The strongly-coupled atom-cavity system with atomic center-of-mass motion included in modeled by semiclassical nonlinear Heisenberg equations of motion with two degrees of freedom. At exact resonance between the internal atomic transition and the cavity eigen frequency, the internal and translational degrees of freedom are separated from each other resulting in periodically modulated Rabi oscillations and regular translational motion. Near the atom-field resonance, the coupled dynamics is found to be irregular and even chaotic in the sense of external sensitivity to initial conditions. It is manifested as a chaotic motion of an atom in an absolutely regular spatially periodic potential in the absence of any random fluctuations. This effect may be explained as a result of the interaction of nonlinear resonances in the atom-field nonlinear pendulum whose low- frequency translational motion is modulated by the high- frequency Rabi oscillations. The irregular motion is studied in detail in numerical experiments using the arsenal of methods of the dynamical systems theory. The results obtained are compared with recent experiments with ultra cold single atoms interacting with single photons in the strong-coupling regime. We estimate the ranges of the system's control parameters, the detuning, the recoil frequency, and the mean number of intracavity photons, in which the interaction of nonlinear resonances may lead, under realistic conditions, to local instability of the center-of-mass motion and some manifestations of dynamical chaos, the effect which is of interest in studying the quantum-classical correspondence and quantum chaos in atomic optics.

Theoretical study and computer simulation results for stochastic dynamics of two atoms trapped in an optical dipole trap under action of a probe resonant radiation are presented. The radiation force correlations resulting form our model lead, in addition to cold collisions, to a tendency for atoms escape in pairs form the trap.

Kinetic equations describing atomic behavior in non-resonant classical and broadband squeezed fields are received. It is shown that the main parameters of squeezed field can be obtained from the decay of two-pulse photon echo.

We show for the first time an explicit expression of the linewidth of an EIT resonance in an inhomogeneously broadened three-level (Lambda) system, and the conditions for the dependence of the linewidth on a driving field strength. Both gaseous systems with the Doppler effect and solid media in which inhomogeneity of the crystalline field results in a broad distribution of atomic center frequencies are considered. We find two extreme cases: in one extreme the linewidth of EIT resonance is proportional to the intensity of a drive laser. And in the other it is proportional to the Rabi frequency of a drive laser, which recovers the result obtained by Feld and Javan. The dispersive properties of EIT, leading to slow group velocity of light, in an inhomogeneously broadened system are also considered.

We have experimentally investigated the potential of narrow coherent population trapping (CPT) resonances for precision applications like magnetometry or atomic frequency standards, using the D lines in thermal Cs or Rb vapor. The magnetometer operates by monitoring the position of the Zeeman-shifted outermost resonance component. The central Zeeman component is well suited for frequency standard applications because its position is shifted by magnetic fields only in second order. We derive the required pair of laser fields form a special diode laser by direct modulation of the injection current. Magneto metric sensitivity down to a picotesla and 10^-12 relative instability for a finger-sized clock have been achieved in this way. Use of a magnetic gradiometer allows to cancel fluctuations of ambient magnetic fields to a large degree, making possible sensitive measurements even outside magnetically shielded rooms.

An experimental scheme of femtosecond optical clock is described. The characteristics of the elements and blocks of the setup are given. Possible application areas of the optical clock described are discussed.

We present a highly sensitive method of pump-probe polarimetry for measurements of small pump-induced polarization rotation and ellipticity. The sensitivity of the method is analyzed for technical and shot-noise probe power fluctuations. The optimal polarimeter configuration is found. We show that it is possible to enhance the sensitivity to the pump-induced ellipticity by setting a small probe ellipticity inside the polarimeter with the help of a small shift wave plate. We applied the method in cw and ps measurements of photoinduced polarization parameters in a nanopolyacetylene film. The typical measured angles of polarization rotation were approximately 10^-5 and approximately 10^-8 rad in the cw and ps experiments, respectively.

Spectral modulated interference fringes are observed in the form of the periodical modulation of broadband spectrum at the output of interferometer provided with a subsequent spectrometer. Group optical path difference of interfering light waves corresponding to the distance from the surface to be measured is characterized by the phase function or fringe frequency of the spectral modulated interferogram. The phase locked loop (PLL) method was used to demodulate spectral fringes. It is supposed a priori unknown carrier fringe frequency, and PLL technique is realized in iterative mode to calculate full fringe phase. At the first iteration step the fringe phase equal to zero is supposed. The second iteration takes the demodulated phase found form the first iteration, etc. As a result, the phase function of the spectral fringes is found. Method was verified experimentally with application to the analysis of the spectral modulated interferograms inherent in Michelson interferometer excited by a low-coherent source.

The research results of autodyne signal formation in the interference systems based on the use of external optical feedback have been presented. The possibility of measurements of vibration characteristics with help of laser autodyne interferometry has been proved. The solution method of reverse problem in autodyne interferometry of nonharmonical vibrations has been described. Considered method allows to use for autodyne system the methods of the determination of amplitudes and forms of mechanical vibrations using for interference system separated from the light source.

The propagation parameters and their relation with the medium properties were investigated for surface polaritons excited in coated cylindrical waveguide. The possibility of excitation of symmetric and antisymmetric types of polariton's modes has been demonstrated for a cylindrical three-layer waveguide with a metal cladding. It has ben shown that the near field of cylindrical surface polariton can be theoretically localized to an arbitrarily small space. The conditions for total localization of the near field of the TM₀-mode were determined by numerical simulation for three-layer waveguide with a metal core. The result of this analysis can be used for development of more effective probes for IR near-field devices.

Second-harmonic near-field optical images of nonlinear nano- objects placed at the surface of a substrate are calculated for different polarization configurations by making use of a new approach to solution of macroscopic self-consistent field equation of Lippmann-Schwinger type. Numerical simulations are carried out for the case of illumination with a linearly polarized Gaussian beam. It is found that the appearance of second-harmonic images can be used to deduce the symmetry of the nonlinear susceptibility tensor of the object and that of the substrate.

It is shown that for integrating control of thickness of uniform metal films along surface samples, an amplitude measuring is more promising in comparison with phase one.

It is shown that modification of Kretchman's scheme by deposition of dielectric thin film on the metal layer allows the sensitivity of the device to adsorbed layers to be increased. An analytical solution of the inverse problem of adsorbed layer parameters determination is obtained.

The problem of the guided mode scattering in an integrated planar optical waveguide with 3D small statistic irregularities is described. The possibility to restore the autocorrelation function of the substrate surface roughness from the far zone 2D scattering diagram in the presence of the additive stochastic white band-limited noise is demonstrated.

A simple model of the Voigt spectral profile is employed to analyze the influence of the sizes of a vapor cell on the shape of the spectral contour of the linear susceptibility. The width of a resonant spectral line observed in transmission and absorption spectra measured with such a vapor cell is shown to tend to the natural width as one of the sizes of the vapor cell approaches the wavelength of the spectral line, thus opening the way to extend the Romer- Dicke pillbox-cavity approach to microwave spectroscopy to the optical range. The possibility of using (lambda) -thick vapor cells, as well as one- and two-dimensional photonic band-gap structures for high resolution measurements is discussed.

Principles of formation and controlled propagation of switching autowaves in optically bistable interference structures are considered. On this basis methods and devices are developed for read-in, storing, read-out, switching and transfer of information light signal sin the plane of 2D- arrays of nonlinear optical elements of micron size. A peculiarity of these methods is the possibility of shift data laterally in the array's plane in a direction that is perpendicular to the direction of incident light beams without its interim transformation into electrical signals. This distinctive feature enables developing new architecture concepts of optical information processing systems. Examples of numerical simulations and experimental realizations are presented of optical digital devices with a wide range of functional applications such as Boolean logic elements, shift registers, multiplexers/demultiplexers, basic planar ring processors, etc. The limiting operation parameters of the above devices are discussed.

Cavity solitons (CS) appear as self-confined light peaks embedded in the transverse profile of a homogeneous coherent field propagating in a nonlinear cavity. They have recently been predicted for GaAs semiconductor micro cavities for which we have developed a microscopic model that describes the field and the carrier dynamics inside the active region. Here we improve our previous model by adding the temperature dynamics. A detailed study of the instabilities affecting the homogeneous stationary state of the output field is performed. In this way we can address the numerical research of patterns and CS. We then show how it is possible to study intrinsic stability properties of CS by means of semi- analytical techniques that allow to describe the destabilizing mechanisms for solitons, mutual interaction properties and their response to perturbations; possible conceptual schemes for optical information treatment and logic gates are investigated.

Physical reasons for the development of false writing information in 3D-memory devices realizing on nonlinear absorption are analyzed. It is shown there are some physical mechanisms, which induce writing of information in additional domains. These domains can be stationary or can be moving periodically or not as in positive or in negative direction of longitudinal axis. The formation of additional domains with written information due to transformation of initial Gaussian beam to ring beam is described. The existence of moving domain under the action of collimate ring beam is discussed. This mechanisms of moving domain realization is different from well-known mechanism of domain formation under the action of focused Gaussian beam. In this paper the formation of additional domains of written information due to distinguish of beam radius on transverse coordinates are shown. Writing of false information occurs for focused laser beam if using VT-relaxation process in experimental setup. An influence of layer-like structure on appearance of false information domains is discussed as well.

A different model approaches to the solving of thermal problems in a vertical-cavity surface-emitting laser arrays have been development. The basic attention concentrates on the analytical analysis for the thermal field out of the laser area. Thermal reciprocal cross-talk in a VCSEL's operating are considered.

We report theoretical and experimental study of two-wave mixing dynamics in the film of azo-containing polymer with liquid crystal properties. The developed model of energy coupling in the polymer considers the effects of light absorption, nonlinear saturation and diffusion. Two geometries of exiting beams incidence were considered: (I) symmetrical incidence with respect to film normal and (II) incidence of differently tilted incoming beams. In the carried out experiments we have investigated the dynamics of two-beam coupling using the prototype of adaptive interferometer. The influence of operation conditions on the response characteristics was studied. The obtained theoretical results are in good agreement with the experimental data.

Image enhancement and evaluation play an important role in modern information and measurement technologies. An important image kind is obtained in coherent systems in holography and interferometry in the form of fringe patterns. Because of the physical and technical limitations fringe patterns are often distorted under the noise influence. It is proposed new noise-immune method for fringe pattern enhancement and evaluation. Unlike conventional filtering methods, in this method a filter impulse response is formed by the local empirical histogram modification with the spatial weighting function inside a dimensionally-varied area dependent on the local fringe intensity distribution. High efficiency of the method was verified experimentally when processing real noisy distorted fringe patterns.

Using single-defect single band mode, a large value of the exponential gain coefficient is obtained by degenerate two- picosecond light pulses in a photorefractive GaAs:EL2 crystal in the presence of an applied magneto-static field. The influences of a cd magnetic field on the temporal recording and erasure of the grating are analytically analyzed. A significant enhancement of the diffraction efficiency of the recorded hologram by a factor of 2 is obtained. The results are good qualitatively in agreement with the experimental observations.

We present a new experimental setup for optical storage of information via refreshing by inverse seeding (OSIRIS), which allows a sixfold increase of the storage time of holograms in a Ba_0.77Ca_0.23TiO₃ crystal. The setup consists of two four-wave mixing processes with common amplified signal waves and phase-conjugated waves. Temporal behaviors of the amplified and pc-signal waves for the OSIRIS experiment as well as for the common four-wave mixing experiment are compared and discussed. The solutions of coupled equations under the depleted-pump approximation are obtained in order to estimate the pc-reflectivities and coupling gains of gratings inside the crystal.

It has been shown that conditions and peculiarities of bistable regimes by acoustoelectrooptic interaction in cubic non-centrosymmetrical crystal are determined by presence of gyrotropy. It has been established that more essentially the latter is displaying in doubling of number of bistable regions and in appearance of dependence of conditions for realization of bistable regimes on polarization of incident light wave. It has been obtained the opportunity of change of switching character by reversion of external electric field.

The basic parameters of optical logic elements AND with three inputs are estimated. The logic elements are based on complex fiber Fabry-Perot resonators, formed by two Bragg reflectors and one end mirror. Such a logic element producing of half-adder in a one switching tact can be used for algorithmic acceleration of optical computing. Considered optical logic elements can be used for preliminary information processing in fiber interconnections between chips or blocks of computing systems.

The architecture of parallel optoelectronics adder, in which the spectral compression corresponding to inputs permits to accelerate algorithmically optical data arrays processing, has been developed. This approach excludes galvanic connections corresponding inputs/outputs and make it possible to perform parallel computation in a wide frequency range.

The maximum achievable characteristics of optical communication systems with different kinds of pulse position modulation have been investigated within the framework of the number-state model. It is shown that the ultimate efficiency in optical systems with ordinary pulse position modulation is determined by the ratio of the number of photons in the signal chip to the number of chips in the signal frame. Maximum achievable efficiencies of all considered methods is compared also. The companions shows that at great values of modulation format the ultimate efficiency of pulse position modulation is higher than that of the multipulse modulation. Overlapping pulse position modulation is shown to be the most favorable one for communication channels. The application of additional encoding to such systems allows to achieve the highest power efficiency of information transmission in optical communication channels.

The maximum cross-polarization gain in cubic photorefractive optically active piezo crystals is considered. It is shown that values of the maximum gain depend on the polarization angle and the presence of piezoelectric effect in the photorefractive piezo crystals. The cases of two values of thickness of the Bi₁₂SiO₂₀ crystal are investigated theoretically. The values of the polarization angle are calculated for which the cross-polarization gain has maximum magnitude.

Dynamics of switching waves in optically bistable all- epitaxial GaAs/GaAlAs Fabry-Perot interferometers is studied experimentally. Realization of planar optical shift register based on propagation of switching waves between neighbor pixels in the plane of bistable layer is proposed.

In the case of erbium doped fiber amplifier, noise and distortion characteristics degrade due to the characteristic of optical component. The resonant enhanced optical non- linearities and dispersion caused by erbium ions in a glass matrix influence the performance of Erbium. This paper reports on analysis, how the non linearities depends on fiber parameters thereby effecting the performance of erbium doped fiber amplifier. The analysis contains measurement of gain and noise figure of erbium doped fiber amplifier for different level of pump power and reflectivity, on a system for optimizing noise figure.

We report on collective effects for the limited train of periodical laser pulses when multiplying the number of pulses in the train occurs at some distance in dispersive medium. This phenomena can be treated as one of the cases of the temporal interference of coherent laser pules.

The propagation and the evolution of dissipative solitons in fibers with a gain and a saturable absorption are investigated. It is shown that the combined action of a nonlinear refractive index resulting in frequency chirp of pulses and of a frequency dispersion of gain induces the negative feedback. As a result, the sequence of dissipative solitons is stabilized: the weak pules are suppressed, the powerful pulses with different amplitudes are equalized.

Two variants of cascade acousto-optic diffraction for the shifting the frequency of an optical beam in considerable values are described and investigated. Methods are based on the peculiarities of the anisotropic diffraction in anisotropy media and allow the points of diffraction to separate. The methods are confirmed experimentally with using of TeO₂ and LiNbO₃ mono crystals. A number of applications for the optical processing and pulse processing are proposed. The wavelength-division-multiplexing and the optical image compressing on the basis of the proposed diffraction are discussed.

Quantum cooperative cluster is an optical microcavity + dot computer generated hologram with N-wave coherent pump. The coherent superposition of the pump waves coincides in phase with the cavity mode, has the supercritical coupling with an atomic ensemble in a cavity, and appears to be a source of the parametric excitation of the superradiance in a microcavity.

In the present paper we investigate two different holographic record modes realized in dye-polymer media. Both methods - dynamic and stationary - are applicable to the same sample and are reversible. Dynamic recording is caused by triplet photochromism of dyes and it may be used to receive versatile information about photophysical properties of substances. Stationary relief-phase holograms are recorded through heat generation under laser radiation is absorbing and are noted for high diffraction efficiencies. Scanning probe microscope was used to instigate the relief- phase holographic grating.

The problem of optimization of the adaptive optical system using local curvature sensor is discussed. Computer simulations of the sensor including closed-loop operation are based on ray-tracing technique and numerical solution of Poisson equation by FEM method. Wavefront restoration for both axial symmetric and non-axial symmetric phase distortions is examined. It is shown, that choosing appropriate geometry of the actuator external electrodes one can improve wavefront restoration for the case of non- circularly symmetric Zernike aberrations.

A Nd:YAG laser with intracavity polarization decoupling of channels to be used in devices for the recording and development of holograms on photo thermoplastic materials. The device ensures obtaining of nanosecond radiation pulses of the second harmonic for exposure of photo thermoplastic media and millisecond IR radiation pulses at the fundamental frequency for proximate development of relief-phase holograms on photo thermoplastic materials. The method of the intracavity polarization and spatial uncoupling of Nd:YAG laser and its double-frequency irradiation is proposed.