In this paper, recent experiments performed in our laboratory are reviewed, which deal with the investigation of quantum phenomena in the radiation interaction of single atoms. The first part describes experiments in single mode cavities, using the one-atom maser or micro maser, and in the second part experiments with ion traps are summarized. The latter experiments concentrate on the investigation of resonance fluorescence. In addition, new experimental proposals using ultracold atoms in cavities and traps are discussed. In those future experiments the interplay between atomic waves and light waves is important, leading to new phenomena in radiation-atom interaction, such as the modification of the Rabi vacuum splitting.

Radiation properties of an atom, moving in a magneto-optical trap are subject to change along its trajectory, due to variations of intensity and polarization. The emphasis of this report is to explicit simple models for the influence of diffusive atomic motion on its radiative properties. Various extensions for improved models are discussed.

We have studied suboptical wavelength atomic gratings, generated by the interference of atomic de Broglie waves in a time-domain interferometer. Three short optical standing- wave pulses, detuned from resonance with a cloud of approximately 100 (mu) K⁸⁵ Rb atoms, act as phase gratings for atomic matter waves. The first two standing- wave pulses, separated by time T, produce a sequence of atomic density gratings of periods $lamda/4 at time 1.5T after the first pulse. The dependence of our signals on the time separation of the pulses is in good agreement with our theoretical predictions. As far as we know, this is the first time when the formation of a high order matter-wave diffraction grating was observed in real time. This demonstrated ability to produce sub-wavelength structures makes our techniques applicable to atomic beam lithography.

Experimental results on phase-space imaging of a laser- cooled atomic cloud are presented. Both position and velocity information are encoded in the frequency of the signal coherently radiated from the cloud. This encoding is achieved by application of a position-dependent magnetic field. Fourier transformation of the signal yields a projection of the phase-space density of the atoms. Since the projection direction is determined by the imposed field gradient, we can reconstruct the phase-space structure of the cloud and trace its time evolution.

We study nonlinear dynamics in the fundamental cavity QED system, consisting of a point-like collection of two-level atoms moving through a single-mode cavity, with a spatially inhomogenous field. In the semiclassical, strong-coupling and rotating-wave approximations, the model is shown to be integrable with atoms moving at exact resonance through a cavity with an arbitrary spatial profile of the mode along the propagation axis. The general exact semiclassical solution is derived in an explicit form, in terms of Jacobian elliptic functions. Numerical simulation confirms that perturbations, which are produced by a modulation of the coupling between moving atoms and a cavity mode, provide, our of resonance, a mechanism responsible for Hamiltonian chaos. Taking into account the interatomic quantum correlations, we go beyond the semiclassical model and derive a dynamical system, which is able to describe vacuum Rabi oscillation with moving atoms. At resonance, this system is again shown to be integrable with a general semiquantum solution found. Out of resonance, it can demonstrate chaotic vacuum Rabi oscillations, which may be considered as a new kind of reversible spontaneous emission.

We propose a coherent beam splitter for atomic beam, based on reflection and diffraction of the atom by a modulated evanescent wave, created on a quartz plate with the periodic surface microstructure.

Simplectic tomography of the one-mode problem of an ion in a Paul trap, and of the two-mode problem of an ion in a Penning trap is discussed. The marginal distribution of quadrature for nonlinear coherent states of a trapped ion is studied. The N-mode tomography for nonlinear coherent states and Schrodinger cat states is considered.

The motion of atoms in a dark magneto-optical lattice is considered. This lattice is formed by a nonuniformly polarized laser field in the presence of a static magnetic field. Cold atoms are localized in the vicinity of points where dark states are not destroyed by a magnetic field. As a result, the optical interaction tends to zero (dark or gray lattices). Depending on the field configuration, such a lattice can exhibit one, two, or three-dimensional periodicity. It is shown that in 1D and 2D, mark magneto- optical lattices the effects connected with the Bose- statistics of particles can be observed under the temperature 10^-5 - 10^-6K and densities 10¹¹ - 10¹²cm^-3, those are usual for current experiments on laser cooling.

The dark magneto-optical lattice for atoms with J yields J -1 transition is considered. The periodic potential is formed using a (sigma) ⁺ - (sigma) ^- laser field and a uniform magnetic field orthogonal to the light waves propagation. The dynamics of slowly moving atoms is investigated for J equals 1 in the quasiclassical approximation. The cases of a weak and strong dark states destruction by the magnetic field are analyzed. The sub- Doppler cooling for a blue detuning from resonance is demonstrated for a low laser field power. The dark atomic lattice creation in the case of the light-induced shift is much less than the Zeeman splitting is predicted.

We have developed the quantum theory of the interaction of ultracold atomic ensemble with the electromagnetic field of vacuum and laser photons. The main attention is paid to the consistent consideration of dynamical dipole-dipole interactions in the case of the second quantized matter. We show that the retardation effects significantly influence the behavior of atomic ensemble in the radiation field. We have derived the general system of equations, which can be used for the investigation of various linear and nonlinear phenomena in atom optics. As an example, we have considered the diffraction of ultracold atomic beam by the standard laser wave. We show that with the increase of the initial density of the intensities of diffractions modes decrease. We also show that the angles of diffraction for different modes depend on the density.

This paper discusses theoretical research of Bose-Einstein condensation phenomenon, for the system of nonacting atoms in the one-dimensional quasistanding resonant field. For the case of shallow potential gaps, one has concluded the main equation, what sets a relation between main parameters of our system, i.e., between chemical potential, temperature, concentration. On the base of this equation, the numerical calculations have been performed for finding out the peculiarities of behavior of atoms at low temperatures (10^-6 K) for fixed values of concentration and the depths of the gap. Then the dependence of the number of trapped atoms on the depth of the gap is considered. One has revealed that for increasing depths, since new zones are not including the gap, the number of trapped atoms considerably increases, due to alteration of the distribution of the state density.

The possibility to copy the unknown polarization of a photon to another photon is considered. The initial idea of quantum teleportation by measuring the Bell operator, describing the polarization, correlations of two photons, seems to be practically unrealizable and the corresponding experiments have been interpreted incorrectly. An alternative method using the optical gate is proposed.

We investigate amplification of optical images by means of a traveling-wave optical parametric amplifier. As shown recently by Kolobov and Lugiato [Phys. Rev. A 52, 4930 (1995)] for a cavity-based geometry, such a scheme can amplify images, without deteriorating their sign-to-noise ratio, thus working as a noiseless amplifier. Here we consider a configuration without cavity, which is more realistic for a possible experimental realization. We investigate in detail the quantum fluctuations of the amplifier and formulate criteria for its noiseless performance. The spatial resolution power, which guarantees noiseless amplification is estimated. We demonstrate how the optimum phase matching of a phase-sensitive wavefront of the image can improve the noise performance of the amplifier and bring it to the ultimate value achievable under given physical conditions. We discuss the effect of improvement of the signal-to-noise ratio in the case of observation of both the input and the amplified image, with an ideal photodetector of small area (i.e., much less than the coherence area of the amplifier). This improvement is due to the fact that the signal-to-noise ratio in the input is deteriorated by the observation with the photodetector of small area.

A process of squeezed light generation by electron beam in a field of two strong external electromagnetic waves propagating in the counter directions is considered. In such a field the electron bunches are formed. Each bunch can be considered as a simple electron mirror placed in a minimum of an effective potential. The input fluctuations change the position of the minimum, providing a parametric interaction inside the system. The squeezing of the output waves is considered. To obtain a large squeezing coefficient one has to mix with proper phases the electromagnetic waves leaving the system from two opposite directions.

Currently, it is obvious [1] that nonstationary tasks of quantum mechanics in more degree differ from those of classical physics than stationary ones. Accordingly, time- domain quantum optics experiments are very important for deepening our knowledge of quantum dynamics. It appears that a single-photon wave (SPW-) packets [2] are the best objects of quantum optics for investigation of the quantum dynamics at macroscopic level. One of the fundamental problems herein is the comprehension of interactions of quantum fields (SPW4MIN and TPW-packets) with macroscopic media. In particular, this is immediately associated with development of our knowledge about the fundamental properties of the irreversibility and of detecting quantum fields. At present, our notion about interaction of quantum fields with a detector, is mainly based on the phenomenological approaches to the properties of the detector [3]. That is why more exact quantum models of macroscopic detectors must be investigated. One of the macroscopic objects, which can be interesting for these purposes is the resonant quantum (Two-,Three-level) medium with phase memory intensively studied in coherent optics. Unusual properties of quantum time-domain interference effects and of photon echoes initiated in resonant media by interactions with an SPW-packet, have been predicted in our works 4LB4-6]. In the present paper study of the quantum dynamics at interaction of the field with the medium we will carry out by investigation of the two photon echo properties. At that, we consider interaction of a three- level (TL-) medium with polarized two-photon wave packets for the purpose of eliciting new nonclassical polarization properties in quantum dynamics of the echo signals.

We present new results on the properties of Celsium and Rubidium atoms trapped in crystalline helium matrices. We have extended the measurements of optical excitation spectra and excited state lifetimes, previously performed in superfluid helium, to solid helium. Cs atoms in the hcp phase of ⁴He exhibit several distinctive features, such as dipole-forbidden transitions and zero-field magnetic resonance lines. We interpret these features as being due to static quadrupolar deformations of the local trapping sites (atomic bubbles). The degree of deformation of the bubbles can be obtained by comparing hyperfine coupling constants in the cubic and hexagonal phases. We have investigated in detail optical pumping of Cs in solid helium, and have gained new insights into the pumping mechanism. We have also succeeded, for the first time, in detecting Rb and Rb in solid helium, by applying an absorption technique, based on driven spin precession.

Silica microspheres behave as efficient optical microresonators when small-volume whispering-gallery modes (WGMs) are used. We have realized a cryogenic set-up to work with microspheres immersed in a superfluid helium bath. Quality factors up to 10⁹ have been obtained at 2 K. In this environment, we have been able to observe a dispersive bistable behavior of the WGM resonances, due to the weak intrinsic Kerr optical nonlinearity of silica, with a threshold power of 10 (mu) W only. This result opens the way to the realization of thresholdless microlaser, based on a rare-earth doped silica microsphere and to other Cavity-QED projects with microspheres at low temperatures.

An alternative approach to the theory of photocounts is discussed. Mechanisms of sharpening of electronic distribution at the expansion of many-electron packets is investigated. Arising of such inhomogeneities initiates a disintegration of many-electron system on smeared on- electron formation. It is shown that interelectronic Coulomb interaction results in the sharpening and localization of such one-electron formations. The motion of an electronic wave packet in the uniform field in the interelectrode space of the vacuum photodetector is investigated. It is shown that the dimensions of such a packet must be of an order or more than one micron. It is shown that such localized charges can give rise to abrupt pulses of the current in the external circuit of the photodetector. The determination of parameters of such a packet by powerful laser pulse scattered is discussed. The motion of one-electron wave packet in the nonuniform field of a negative charged spherical electrode is numerically investigated. It is shown that there is the possibility to unsqueeze electron packets in the transverse direction to macroscopic size by scattering on such electrodes. An experiment of observation of such macroscopic packet on the luminophore screen is discussed.

We show that the technique of Ramsey interferometry may be used to completely determine the quantum state of an electromagnetic field in a cavity. Our method, which allows the direct measurement of the Wigner function of the field, is a useful tool for probing the quantum-classical transition and, in particular, the decoherence between coherent superpositions of distinguishable coherent states of the electromagnetic field in the cavity. We also show that the realization of a controlled-not gate within framework of cavity QED is a special case of our proposal, and leads to the measurement of a negative value for the Wigner function of an electromagnetic field.

The theory of superradiance by an ensemble of two-level atoms embedded in a dielectric host is developed. It is shown that the near dipole-dipole interaction of a dense collection of two-level atoms is enhanced by the presence of the host material, decreasing the pulse temporal width and increasing the peak pulse intensity of superradiative emission. The influence of the inversion-dependent detuning effect on the parameters of the emitted pulses is investigated.

Although the frequency position of the non-coupled state in coherent population trapping does not depend on light intensities, this is not true for the experimentally observed dark resonance minimum. For precision applications, this shift constitutes a major systematic effect. We have measured the light shift in an atomic celsium vapor, as a function of buffer gas pressures. The experimental data for the unbuffered vapor can be reproduced quantitatively with a simple model, taking into account the atomic velocity distribution and the excited state hyperfine structure. The buffered vapor requires a more complicated model.

A new type of accessible source of ultrashort optical pulses, based on the phenomenon of collective coherent recomination (superfluorescence) of electrons and holes in semiconductor heterostructures is proposed. The novel regime of an ultrafast operation of quantum-well semiconductor lasers with a low-Q cavity of length approximately 30 $min 100(mu) is analyzed, in which a quasiperiodic sequence of superradiant pulses of duration up to 30 fs and peak intensity exceeding 100 MW/cm² is emitted under continuous pumping, with typical current density of order 10⁴ A/cm². It is shown that the same process of femtosecond superradiant recombination can be used for the room-temperature generation of optical coherent emission in multiple quantum-well or quantum dot GeSi/Ge structures, employing direct radiative transitions from the T-valley.

We show that three-level atoms can be trapped in the excited energy state, as a result of drastic modification of spontaneous relaxation under the action of strong coherent driving field, when one of two dynamic Stark levels crosses a nearby atomic state.

The formation and propagation of nonlinear solitary waves under Bragg condition in multidimensional resonant photonic crystals is described by analytical and numerical solutions of two-wave diffraction Maxwell-Bloch equations. The existence of nonlinear solitary waves both in the Bragg and in the Laue geometry of diffraction has been shown.

Appearance of coherence effects in resonant Raman and double-A schemes appropriate to the cw experiments on Doppler-broadened transitions of Na₂ and I₂ molecules is discussed. Possibilities for manipulating the resonance shape in optically thick Doppler-broadened media with effects of quantum interference, as well as elimination of Doppler broadening in strong driving fields are outlined.

The coherent population trapping (CPT) under resonance interaction of elliptically polarized light, with atoms having degenerated energy levels, is analytically treated in an invariant way, without using a specific coordinate frame. Tensors describing dark states are found in an explicit and invariant form for all atomic transitions, where CPT takes place. The correspondence between elliptical polarization vectors and pairs of unit spinors is established. It is shown that all dark states in the problem under consideration, can be constructed from these spinors, by taking multiple tensor products. In the case of an integer angular momentum, this general construction is reduced to a multiple tensor product of vectors. A general significance and some applications of these results are indicted.

A probe field propagation in a medium of two-level J_g equals .5 yields J_e equals .5 atoms, has been theoretically investigated. The atoms are pumped by a circular polarized optical field. An applied static magnetic field is orthogonal to the direction of the pump field propagation. The case of the pump is a coherent field and Gaussian- Markovian random process with a finite bandwidth of the noise have been analyzed. We have obtained that one of the normal waves can amplify in the absence of population inversion both for coherent and partially coherent pump. For the pump with a finite-bandwidth amplification occurs when the Larmor frequency and the Raby frequency of the pump are of the order of the pump linewidth, which was taken much broader than the natural width of the excited state.

Our investigation is focused on obtaining analytical results describing the resonance fluorescence and weak probe absorption spectra of a driver Lambda-system under the Raman resonance condition. For the saturation field limit and within the rotating wave approximation (RWA) the resonance fluorescence and weak probe absorption spectra are calculated for the case of unequal driving fields strengths and non-zero one-photon detunings, generalizing the previously known results. A novel contribution derived is the nonpositive nonlorentzian part of the spectrum, originating from the specific quantum properties of the atomic correlation functions. This contribution is asymptotically small under given conditions and, therefore, determines behavior of the resonance fluorescence spectrum wings and the absorption spectrum in the vicinities of the driving field frequencies. Beyond the RWA, the spectral structures due to the off-resonant four-photon atomic excitations are calculated. They consist of a coherent and two broadened spectral lines centered at the four-photon frequencies 2(omega) _L-(omega) ¹_L and 2(omega) +1)_/ - (omega) _{L4/ respectively, where (omega l} and (omega) (superscript 1$_L are the driving laser frequencies.

The modification of the relaxation rates due to the strong driving provides a novel mechanism of inversionless amplification, which is especially effective in schemes with bichromatic probe field.

We present a new exact solution of Maxwell-Schrodinger set of equations. This solution describes propagation of a laser pulse through a (Lambda) -type medium, where the initial atomic state is prepared in the form of spatially-varying coherent superposition of low-energetic states. The solution describes a new type of transparency, which is characterized by a transformation of frequency of the incident pulse. Specifically, this type of transparency can be used for creation of an 'optical key' and a frequency converter.

We theoretically study cw two-photon resonant four-wave mixing process (formula available in paper) when fundamental radiation with frequencies (formula available in paper) are strong enough and lead to coherent population trapping (CPT). It is shown that under conditions of CPT, the linear and nonlinear polarization can be the same order. Efficient nonlinear frequency conversion in atomic Ba vapor in cw regime is demonstrated.

The possibility of elimination of Doppler broadening and simultaneous coherent coupling of atoms from wide velocity intervals in three-photon schemes is shown. A simple physical analysis in terms of modification of frequency- correlation properties of multiphoton processes in strong fields is given. Numerical illustrations are presented.

The features of spatial propagation of two partially overlapping short resonant pulses (counterintuitive pulse sequencing) in an absorbing medium of three-level atoms under conditions of adiabatic population transfer are investigated. We find that pulses can propagate with practically constant amplitudes in a medium with length much higher than the absorption length. It is shown that adiabatic population transfer creates full population inversion on a dipole-forbidden (Raman) transition over the way of pulses' propagation. We suggest use of this technique for conversion of picosecond laser pulses into tunable coherent anti-Stokes radiation.

The possibility of the high-selective photoexcitation of molecules of a gas medium is shown on the basis of the coherent population trapping of sublevels of the ground term at the optical pumping by the two-frequency laser radiation. Such photoexcitation may be used in the technology of the isotope (isomer) separation, photochemistry and molecular biology, even in cases of comparatively dense media, when the selectivity has few of the usual methods of the laser action.

Coherent population trapping effect is widely studied for simple three-level systems of different types ((Xi) 2, (Lambda) , V)^1,2. For real atoms the situation is more complicated. Atomic levels are degenerated one and in the presence of external fields coupling of magnetic sublevels appears due to radiation, so magnetic fields leading to the systems of levels of the higher order. Our theory and method of calculation for interaction of multilevel atoms, with intense radiation fields in the presence of external magnetic fields have been applied for considering coherent population trapping effect for such systems. In the absence of magnetic field for considering sets of parameters, we can see the behavior of populations in function of time, detunings for both systems of coupled sublevels inherent to the coherent population trapping effect. In the presence of magnetic field, we can see novel features in the populations for the systems of coupled magnetic sublevels.

Frequency standard at 732 nm for absolute measurements of the muonium 1S-2S transition frequency has been developed. A suitable reference line for that standard was found in the absorption spectra of the iodine vapor heated up to 600 degree(s)C. In order to measure the absolute frequency of the developed standard, an optical synthesis chain was built up. The frequencies to be measured were synthesized from two secondary standard frequencies: a frequency of the diode laser stabilized to rubidium absorption line and a frequency of the CO₂ laser, locked to CO₂ absorption line. An accuracy of the measurements is order 10^$min9.

The new Faraday mirror for compensation of parasitic optical anisotropy in two pass single mode fiber optic systems, is proposed and experimentally tested. Proposed Faraday mirror is based on ring polarization Sagnac interferometer with Faraday cell placed on the way of counterrunning waves. Unlike conventional Faraday mirrors, where precise compensation is achieved only when Faraday rotation angle is exactly equal to 45 degrees, proposed ring interferometer based Faraday mirror is not sensitive to deviations of Faraday rotation angle from 45 degrees. In the experiment, where the quality of polarization restoration by both conventional and new Faraday mirrors have been compared good compensation by new Faraday mirror has been observed in wide range of Faraday rotation angles. As the experiment shows new Faraday mirror has the better performance then conventional one even at the angles of Faraday rotation close to 45 degrees. New FM may be applied in the fiber optic interferometric sensors, where high polarization stability is needed.

The recent interest in the development of high-sensitive, low frequency microphasemetry methods have been inspired as for tasks of fundamental physics, in particular, by the programs for gravitational waves measurement, as for applied physics, such as creation of high sensitive interferometric sensors for a number of physical values-acoustic, magnetic, and for displacements in atomic force microscopes. The present work provides a comparative analysis of the influence of quantum (shot) noise on the limit sensitivity (signal-to-noise ratio) in microphasemetry in the common regime of operation, in the steep region, and at the minimum of an interferogram with modulation of phase difference for a number of interferometric schemes. In this work, we consider the standard Michelson interferometer, Fabry-Perot cavity, and a more complex system, in which Febry-Perot cavities appear as Michelson arms. To show the results in more convenient form, we put it into the table.

The algorithms developed can be used for any application, which requires tridimensional visualization and additional processing of experimentally acquired images. This paper especially refers to image processing and visualization in laser beam analysis. The information, acquired by a CCD camera and stored as a matrix of gray levels, is processed and the result is a 3-D representation of the beam intensity profile. An interpolation-and-averaging method (independent of the matrix dimensions) was developed, aiming at reducing the time required for data representation in on-line applications and also to diminish the camera noise and sampling errors. The experimental works were performed using a COHU 4913 camera, connected to an LBA-100 laser beam analyzer, which were coupled to a PC compatible computer. Several lasers, such as He-Nw, He-Se, pulsed and cw Nd:YAG lasers, laser diodes, and laser diode arrays, operating at different wavelengths, were studied. The developed algorithm was implanted on the computer, so that the overall system performances were improved, obtaining a user-friendly interface for data visualization and further processing.

The design and the principle of action of a laser multibeam interferometer are presented. The device is intended for the registration of the small spatial changes of refractivity. Compared to known prototypes, it has higher stability to the influence of different vibrations and high jamproofing. Under ordinary laboratory conditions, it allows measurement of the values of the refractivity changes of about 10^-10.

The application of optical superresolution technique to measuring small particles, said to be secondary light sources with various scales of sizes - from micrometers to nanometers, is discussed. The concept of a separate nanosized object and theoretical approach to recognition of its size through the mathematical continuation of the visible angular spectrum of vector plane waves suggested.

Opportunities offered by the immersion surface-plasmon (SP) microscopy for acceleration detection, have been investigated. A scheme of an immersion SP-accelerometer, enabling one to detect linear acceleration and find its direction, as well as to evaluate the module of a uniform acceleration with the accuracy of 10⁶ m/s^s, is considered.

It is shown, that the Doppler line from a single large particle moving with a constant velocity through a finite- width laser beam, undergoes a doublet-type splitting under specific observation conditions. A general requirement is that particle size 2a is not negligibly small, compared with beam diameter 2w_$0. Three optical mechanisms of line splitting are considered. The first one is based on nonsymmetric diffraction of a bounded laser beam by a moving particle. The second arises from the transient geometry of diffraction. The third mechanism, of photometric nature, originates from specific time variation of total illuminance of moving particles when 2a>Lambda, the interference fringe spacing in the measuring volume. The diffraction splitting is observed when a detector is placed near one of diffraction minima corresponding to either of probing beams, and 2a equals (n0.5)Lambda for n equals 1,2. The photometric splitting is observed with an image-forming optics, when 2a equals n(Lambda) . That gives the possibility of distant particles sizing based on the Doppler line splitting phenomenon. A general theory of line splitting is developed, and used to explain the experimental observations quantitatively. The influence of the scattering angels and observation angle on the line splitting characteristics is studied analytically and numerically.

The possibility of sensitivity improvement for parametric transducers with two component pump by new algorithm of data processing is discussed.

The procedure of factoring the square of space-time interval is proposed and briefly discussed in connection with the problems of precise field measurements in fundamental physics. The approach under proposal leads to the appearance of both partial amplitude and partial phase characteristics, describing the space-time intervals. Starting from experimentally established invariant parameters, the analysis of properties inherent in the space-time intervals allows one to reveal the interference of partial amplitude, as well as the origin of nodal filaments, conditioned by the nonintegrability of partial phases.

The model computer solution of the direct and inverse problems was obtained on the basis of the developed theory of the image formation in a waveguide optical microscope. The inverse problem was made with the use of the Tikhonov's regularization and analytical extension of power spectral density. The possibility to achieve a superresolution was demonstrated.

We describe an ongoing experiment to measure parity violation in atomic caesium, based on detection by stimulated emission. Our goal is to measure to 1 percent a left-right asymmetry of 10^-6 to test electroweak theory and look for new physics beyond the standard model. The Cs highly forbidden transition, 6S_.5 - 7S_.5, is excited by a pump laser pulse in a longitudinal electric field E. the PV asymmetry resulting from the weak interaction during optical excitation is converted into an anisotropy in the gain of a probe laser pulse, which stimulates the allowed transition 7S_.5 - 6P_3/2, and manifests itself as a tiny E-odd rotation of the probe linear polarization. Differential polarimetry allows dark- field detection of the rotation angle and discrimination of the PV effect is based on several concepts of symmetry. Original amplification of polarization asymmetry by stimulated emission is presented with perspectives for signal-to-noise improvements.

Precision comparison of refractive action of condensed medium (glass) on light waves propagating in different direction was carried out. Measurements showed that its reaction index is independent of the spatial orientation of the medium to an accuracy of 5 (DOT) 10^-8. It is known that the index equals the ratio between phase velocities of light in air and glass. Hence, it follows from the above-mentioned results, either both of these velocities are isotropic, with greatly high precision or they are equally anisotropic. A special experiment was made of the selection from these variants. The idea of this experiment was to follow dependence of the light passage time along asymmetric loop upon this loop orientation. The asymmetry (provided by placing a glass rod into a part of the loop), should have resulted in dependence of indicated time on light velocity anistropy. It has been established that phase velocity of light in the laboratory can be treated independent on direction with relative accuracy not worse than 5 (DOT) 10^-8 or, perhaps, within two orders better.

Method for phase nonreciprocity measurement in optical ring resonators using low coherent light sources is proposed. Two pass low coherent ring resonant interferometer is considered, in which broadband light is intended to pass through the ring resonator, first in clockwise direction, and then, after the reflection from retromirror, in counterclockwise direction. It is shown that output light power in this interferometer depends on a frequency shift between clockwise and counterclockwise resonances, due to phase nonreciprocity in the ring, as well as light frequency shift by reflection from retro-mirror. Observation of Sagnac effect in low coherent two pass ring resonant interferometer is reported.

The state of the art of the problem for the laser- interferometer transducer resolution increase is discussed. It is noted that the element basis of transducer electronic systems, allows achievement of resolution approximately (lambda) /1024 (or 0.6nm). The problems of accuracy providing the interferometric displacement transformation are analyzed by the example of the control system creation for the precision air bearing table of the laser pattern generator with submicron resolution. The peculiarities of this task solution caused the presence of inner heat and turbulence sources are considered. Examples of the known technical methods for solution of this problem are shown.

Light-induced charge gratings on photorefractive materials are investigated using electrostatic force detection with an atomic force microscope. The high sensitivity of the detection method permits - for the first time - the study of charge gratings on very thin photorefractive polymer films (50nm and 80 nm), which cannot be investigated by optical means. Profiles of charge gratings on Bi₁₂SiO₂₀ crystals and on polymer films are observed. In addition, the time development of such profiles during the writing process and the decay is investigated. The excellent lateral resolution of the force measurements leads to the detection of a nanostructure in the charge distribution, which is attributed to surface imperfections and changes in the chemical composition of the materials.

The criteria, distinguishing reciprocal media from nonreciprocal media are well known. However, with the development of fiber ring interferometry, effects of phase nonreciprocity caused by polarization effects, have been found in media, which are reciprocal in the traditional meaning. The polarization effects occur when waves, which have been equally polarized at the input, become differently polarized after passing through a fiber ring interferometer in counter directions. There are some papers, which provide calculations and results of experiments on the effects of polarization nonreciprocity for concrete schemes. The aim of the present work is to summarize the known results, and to analyze the effects of polarization nonreciprocity based on the general Jones matrix of FRI, which satisfies the well- known criterion of reciprocity.

The express method of determination of microstep parameters (height and width), based on the comparison of the complex simulated responses with the experimental one has been elaborated. A superresolution in determination of object lateral parameters is obtained using a priori information.

The LIGO (laser interferometer gravitational-wave observatory) detector is a complex Fabry-Perot/Michelson interferometer, designed to detect gravitational waves (GW) from astrophysical sources. When a GW strikes the detector, the underlying space will be extended in one direction and contracted in the orthogonal direction. The LIGO detector is designed to detect this space-strain, as a relative change in the lengths of the mutually orthogonal arms. Because this strain is much smaller than the arm length (typically 1 part in 10²¹), each arm is in the form of an optical resonator, effectively increasing the arm length and, hence, its change for a given strain. The arm-length change is measured as the relative phase shift at the beam splitter. To cope with the tiny phase shift, LIGO detects it as a beat signal between a carrier frequency and a side band frequency at the signal port (also called the dark port) of the Michelson interferometer. The side band is generated by phase-modulating the carrier frequency; the modulation frequency is chosen, so that the side band is far off resonance with the resonators in the arms, while the carrier frequency is on resonance. In this way, the phase shift associated with a relative arm-length change can be detected as amplitude modulation at the modulation frequency.