The intensity of laser light is modulated when reflecting back from a fiber Bragg grating (FBG) which is glued onto a PZT vibrator and expands/contracts as the vibrator vibrates. The wavelength of the laser light is tuned to the slope of the FBG reflectance curve as a function of optical wavelength. Measuring the modulation component of the detected signal, we can directly observe mechanical vibration of the vibrator. The output of the sensor is stable and the involved harmonic component is below the system noise level. It is then believed that the sensor operation is linear. The sensitivity depends on the slope of the FBG reflection spectrum curve at the operating wavelength and is higher for the larger slope. The minimum amplitude of the vibrator measured in the experiment is 4.5 nm, which corresponds to the strain of 2.14 μstrain. Since not only an FBG has little influence on the object under measurement because of its small size and light weight but also its frequency characteristics are thought to be better than a PZT vibration sensor, i.e., the sensor can be used in a wide range of vibration frequency, an FBG is expected to provide us with an important tool of practicality for measuring mechanical vibration.

A fiber Bragg grating phase sensor demodulation scheme is demonstrated in this paper. An unbalanced Mach-Zehnder interferometer is used as the wavelength shift detector. The sensing fiber Bragg grating is attached on a piezoelectric transducer, through which a vibration signal is applied on the grating. To improve the fringe visibility of the output spectra of the Mach-Zehnder interferometer, we investigate the characteristics with detail. We find that there is an optimum optical path difference between the two arms of the interferometer. We successfully design and produce two Mach- Zehnder interferometer whose OPD are about 2.54 mm and 2.12 mm, and the relevant visibility are 9.7 dB, 18 dB, respectively. The experimental results have some potential applications in some regions, such as strain, temperature, and vibration detection.

A measuring system for long-term registration of fast processes in solid state objects under mechanical stresses based on using several single-fiber multimode interferometers (SFMMI) as sensors is proposed. Multi-channel adaptive correlation filter based on photorefractive crystal is used for simultaneous processing speckle signals from SFMMI. Mutual influence of the neighboring channels in crystal is analyzed, and it is shown that the simultaneous processing of several channels can be performed by using a single photorefractive crystal, even if optical fields from different sources are overlapped inside crystal. Such important property of proposed filter as its adaptability allows to separate fast processes of crack generating from slow processes of stress accumulating inside deformed object.

The method of enhancement of local amplitude sensitivity of optical fibers by means of creation of special fiber's <<stop marks>> is developed. The amplitude modulation of guided light at deformation of such <<stop marks>> is investigated. The <<stop marks>> optimal size and shape providing maximal efficiency and linearity of transformation of external actions into amplitude-modulated optical signal are defined. It is shown, that such elements are perspective for seismic sensors development, because they enhance sensor's sensitivity on 59 dB.

It is shown, that the singlefiber doublemode interferometer implanted into structure of a tested concrete unit allows to measure the unit structural deflection, absolute elongation and residual deformations in real time with accuracy not worse, than 0.05 μm. it is also shown, that the developed interferometric method allows to indicate a point of time of unit's crack initiation and to estimate the crack opening displacement.

A problem of tomography reconstruction of functions of spatial distribution of vector physical fields by using two- dimensional measuring network based upon fiber-optics measuring lines having integral sensitivity is discussed. The problem solution was found for cases (1) output signal from measuring lines is formed under action of vector projection, (2) output signal is formed under action of the derivative of vector projection along measuring lines axis. (3) output signal is formed under action of square of vector projection.

The hydrophobic gel freezing influence on the optical fiber cable properties discussed. Is shown, that the locally inhomogeneous gel filling material freezing can cause distributed defects in fiber communication systems.

An idea of nonlinear optical cryptography is suggested. The simulations of the authors demonstrate a possibility of use of a nonlinear ring interferometer with heredity as device of hidden information transmission.

The main advantages of neural networks are the flexibility of architecture and ability to training. These advantages allow using neural networks for solving many difficult problems. One of them is the processing of data collected by fiber-optical measuring systems. The principles of organization of optical neural-like system for analog data processing are represented. The practical realization of this system on a matrix of photoelectric cells allows to obtain a parallel processing of an optical information for physical field distribution reconstruction.

In this paper we demonstrate the design of the fiber-optical measuring network for monitoring of a physical field and the fiber-optical component intended for practical implementation of interconnection matrix of the neural-like processing network. This network will be intended for processing of a data obtained from fiber-optical measuring systems. The component consists on two optical fibers. An optical radiation enters into the first fiber and loses a part of power, which one passes into the second fiber. The value of an emission power distributing in the second fiber will be determined by some factor, which one is determined by a coupling efficiency of optical fibers. The value of coupling efficiency can be changed without interference in a design of the component.

In this paper, according to the coupled-mode theory and adopting the method of extended series, the correlative characteristic between temperature and strain of fiber Bragg grating sensors are theoretically studied and numerically analyzed. The correlative factor is also defined and used quantitatively to describe the correlative degree between temperature and strain. The research has certain significance for applying fiber Bragg grating sensors to practice.

3-D holographic images of extended diffusing objects are simultaneously recorded and reconstructed by optical cross- correlation in a second-order non-linear crystal. An interaction geometry in which the phase-matched object and reference fields propagate slightly non-colinearly is particularly convenient to obtain these Second Harmonic Generated (SHG) holograms.

In this work we experimentally investigated dynamics of nonlinear process of record and reading of the hologram in photopolymer to a Gaussian beams of light. The analytical model of dynamics of record is based on the equations Lorentz- Lorenz and relations of the theory photopolymerization. The record of the holograms was conducted under different corners between bundles of light. The data of experiment have allowed to receive basic physical parameters of analytical model of a record of the holograms in photopolymer: characteristic time of polymerization, time of discussion and coefficient of monomer diffusion. The researched photopolymer was made in Institute of Organic Chemistry of the Siberian Separation of a Russian Academy of Sciences (Novosibirsk).

The formation of photorefractive grating at the symmetric three-wave forward interaction in a cubic optically activity crystal with applied ac electric field is considered for small contrast of interference light pattern. The self-consistent equations describing spatial-temporal dependency of modulation index and amplitude of space charge field is obtained. For high frequency of external field it is shown the interaction reaches of steady state only at the linear polarization of pump light wave. The dependencies of modulation index on interaction length are analyzed for interaction in Bi₁₂TiO₂₀ and Bi₁₂SiO₂₀ crystals with diagonal electro-optic configuration.

Recent studies on silica glass as a photonic material will be described. With regard to the structural disorder, investigations have been made to improve transparency and to shift the optical absorption edge in the ultraviolet towards shorter wavelengths. Remarkable advances have been achieved in the understanding of both light scattering, which is a dominant factor in the optical losses in silica fibers, and the absorption edge. Freezing of the structural disorder was observed, and structural relaxations are found to be important for improving the transparency, whereas for the absorption edge thermal vibration effects seem to be more predominant than the structural disorder. From the results, the present authors have tried to control the structural relaxation for developing silica glass with an ultimate optical transparency, finding that a very tiny amount of the proper impurity species gives rise to structural subrelaxations, which are effective in reducing the Rayleigh scattering. The scattering was reduced by 13% by addition of only 10 wt.ppm Na₂O, for example.

The optical information processing based on time-to-space conversion has been intensely studied for about ten years by many researchers. Recently, the use of this technology in optical communication systems has become attractive because of the increase of modulation bit rate and the development of a high-performance arrayed-waveguide grating. In this report, the applications of this technology to the optical communication systems, including optical code division multiplexing and dispersion compensation of transmission optical fiber are discussed with our research results.

Phase state, chemical composition, and morphology of mechanically polished LiB₃O₅ surface are considered in comparison with as-grown (110) crystal face. Strong enriching of near surface layers with carbon is observed. A way to improve the polished LiB₃O₅ surface characteristics is demonstrated.

The aim of this work is to obtain electro-optical modulators (EOM) for magnitograph which differ from the known ones in the coating current-conducting film on the crystal surface. Such modulators are designed to be used in the observational astronomy.

The digital model of the multicomponent coherent optical system with arbitrary layout of optical elements (lasers, lenses, phototransparencies with recording of the function of transmission of a specimens or filters, photoregistrars), constructed with usage of fast algorithms is considered. The model is realized as the program for personal computers in operational systems Windows 95, 98 and Windows NT. At simulation, for example, coherent system consisting of twenty elementary optical cascades a relative error in the output image as a rule does not exceed 0.25% when N ≥ 256 (N x N - the number of discrete samples on the image), and time of calculation of the output image on a computer (Pentium-2, 300 MHz) for N = 512 does not exceed one minute. The program of simulation of coherent optical systems will be utilized in scientific researches and at tutoring the students of Far East State University.

Ever-increasing volumes of data recording and data processing require minimization of archive storage sizes, which can be efficiently achieved by increasing the density of optical recording. Therefore, in the framework of the present study, it is certainly of interest to explore the possibility of using specklograms recorded with a changed scale for implementing such a task in data array processing as image subtraction. Since specklograms are recorded without any specifically formed reference beam in multimode laser radiation, they display great potential for processing the optical data received from diffusely scattering objects in natural conditions.

Optical lensless methods of processing the periodic image based on the Talbot effect and Fraunhofer diffraction are considered. Regularities of making of image in nonzero orders of diffraction are shown and are explored their noise features. It is shown that without using lenses possible to produce a transformation of image of a periodic object in the Fourier-spectrum on end distances.

A capability of improvement of self-developing dichromated gelatin properties (SD DG) under IR laser radiation action is confirmed experimentally. The laser annealing application for reduction of SD DG layer synthesis time results in increase of diffraction efficiency value and properties uniformity improvement of on all media volume for layers of 1 - 5 mm by depth. The laser annealing represents itself as additional control parameter of such technological process and consists in an adjustable time-space localization of effect, capability by selective energy pumping of a macromolecular system.

Composing a slab-waveguide by spin-coating dye-doped organic monomer onto a glass substrate under UV irradiation to be polymer, frequency selective lasing is observed by the side pumping of an interference pattern of pump beam. The thin-film slab-waveguide consists of Rhodamine B (Rh-B)-doped thio ether methacrylate (TEMA) with the thickness of approximately 2 μm. Pumping the thin-film by the interference pattern of Nd:YAG (SHG) 530 nm laser with the gain period Λ of 15 μm, the lasing output is selectively observed near 610 nm, in contrast to no lasing under a uniform pumping. Both effects of the pump energy on the lasing output and of the gain period on the wavelength are also described.

A pattern transmitting laser is proposed to extract and transmit arbitrarily shaped beams by using coupling-hole mirrors having various shaped holes. This configuration is demonstrated in a slow axial-flow CO₂ laser. As simple examples the coupling mirrors with two holes and a donut (or ring)-shaped coupling-hole are fabricated by evaporating gold film on the ZnSe substrate onto which the circular masks or ring-shaped mask for two holes or a ring shaped hole are attached. The oscillation output from the two holes or ring- shaped hole is successfully obtained and the transmission characteristics are investigated. Image transmission is also demonstrated using a lens system composed of two Fourier transform lenses.

Noncontact reconstructing 3-D objects surface profile on base of projection-shadow method is investigated in this paper. It is shown that this method in contrast to known techniques allows reconstructing a shape of object with vertical sides. Optimal parameters for measuring are proposed. The dependence of relative error of reconstructing on angle of light beam propagating is obtained.

Using of bichromatic radiator (pulse laser source of two- frequency radiation) with minimal desynchronization of light pulses is required to solve a number of the problems of atmosphere remote sensing. In this work an effort is made to clear up the ex-tent to which the desynchronization of laser pulses depends on parameters of the bichromatic radiator and its fluctuations and also to direct the way leading to one of the solving of this problem. In the work we used a computer simulation.

In this paper fractal procedure of covering surface is represented. Subject of investigations is quasicrystal Penrose mosaic (MP) which has axis of symmetry of the fifth order. Elements of MP generation are pair of golden (g) rhombs divided on with conservation of g-relations. Following generations of MP are obtained by iterative procedure. Cayley trees are built for obtained fractal structures. The percolation problem of fractal dimensionality and entropic functionals is solved for obtained graphs.

TSL is a self-propelled underwater vehicle with data-command link to operator on supporting ship by fiber-optical cable. TSL is designed for sonar and video inspection of extended water-filled tunnels and for shallow-water applications. Current version of TSL communication and control system based on fiber-optical connection are described in the paper.

Inhomogeneous illumination of any photoconductive crystal results in the formation of the space-charge field, which is a replica of the intensity distribution. If the crystal also possesses the electro-optic effect, the polarization state of the intensity pattern becomes spatially modulated since the pattern propagates in the self-induced non-uniform electric field. The polarization self-modulation has essentially three- dimensional character. After propagation the crystal of proper thickness, the polarization state of the transmitted light wave can vary from linear through circular to linear orthogonal in spite of the initial polarization being strictly uniform. This modulation can be readily visualized by installation of a polarization analyzer after the crystal. The polarization self-modulation is very important for correct description of nonlinear interaction of light waves in photorefractive crystals. Moreover, it has an important practical application for design of adaptive sensors of speckle-pattern displacements and adaptive interferometers capable to measure transient displacement of rough surfaces with sensitivity approaching to the classical homodyne interferometer.