We investigate both codirectional and contradirectional nonlinear couplers composed of two nonlinear waveguides operating by second- and third-order nonlinear optical processes. We take into account possible mismatches inside the waveguides and between them. Quantum statistical characteristics, such as photon number distribution, its factorial moments, quadrature and integrated intensity variances and quadrature uncertainty product demonstrate generation and transmission of nonclassical light in nonlinear couplers. Incident beams are assumed to be coherent, squeezed and mixed with external noise. Nonclassical behavior of beams generated by the nonlinear waveguides can be transferred to linear waveguides and controlled by linear signal and by linear and nonlinear mismatches. In the contradirectional regime of propagation asymptotic nonclassical states can be obtained.

A brief review of up to date progress of the research on photoinduced self-organized second-harmonic generation (SHG) in optical fibers and doped bulk glass is presented. The writing and reading of self-shaped (chi) ⁽²) grating at the interaction of short optical pulses including Kerr nonlinearities are described and the effective interaction length is calculated with data of published experiments. The effect of saturation of self-organized SHG proposed by the directional photoionization model and the cumulative local- response model is discussed. A new phenomenological model of the beginning of photoinduced self-organized SHG with complex third-order-rectification response function is proposed explaining the mutual shifting of the SH seeding and the SH radiation generated. The self-organized parametric down conversion (PDC) is proposed for a very effective preparation of optical fibers or bulk glass samples.

The numerical solutions of hybrid modes equations describing monochromatic electromagnetic fields propagating along the boundary between the nonlinear Kerr medium and linear dielectric are obtained. The dependence of the mode structure on the nonlinearity mechanism and the propagation constant is discussed. The analytical expressions approximating the fields of the lowest order mode are reported. These expressions are applied to the boundary problem at the interface between the Kerr medium and the linear cover. The approximate formula describing power flow along the boundary is derived. The accuracy of the applied approximation is analyzed.

Intensity-controlled nonreciprocal coupler is proposed and studied analytically and numerically. The structure consists two planar waveguides -- the dielectric waveguide and the asymmetric magneto-optic waveguide -- coupled through a nonlinear Kerr-type medium. The operation of the device is based on the nonreciprocal phase shift for TM modes in magneto-optic waveguide. The coupled mode equations are solved analytically in terms of Jacobian elliptic function. It is shown that the transmission of the device is affected by the intensity of light in different way for the backward and the forward propagation.

In experiments, pulses of two-mode squeezed light were generated by an optical parametric amplifier. For certain ranges of parameters the joint photon number distribution of two-mode squeezed coherent states exhibits nonclassical oscillations. The nonclassical features were explained using the interference-in-phase-space concept in four-dimensional phase space. We investigate joint phase distribution of two- mode squeezed coherent states for presence of peaks and attempt to relate the peaks to the manifest oscillations in the joint photon number distribution.

Methods of analysis of aberrated laser beam propagation were reviewed. Thermally induced wavefront aberrations occurring in end pumped lasers calculated in framework of ray equation were the subject of analysis. Influence of such aberrations on M² parameter, Strehl ratio and kurtosis of beams with Gaussian intensity distribution were determined. The propagation of such aberrated beams in Fresnel diffraction approximation was described, and examples of caustics of such beams were calculated and discussed.

A decentered Gaussian beam is a recently introduced generalization of an ordinary Gaussian beam, the propagation of both of which through an arbitrary centered paraxial optical elements can be described by ABCD matrices of paraxial optical rays. The paper shows that the M² beam quality factor of the decentered Gaussian beam is the same as that of the ordinary Gaussian beam -- equal to 1. We further find out general conditions (for elements with pure real ABCD matrices) which must be fulfilled in order to accomplish the transformation of the Gaussian beam into decentered one or vice versa. The particular cases under specific conditions are presented in the work as well.

The comprehensive, three-dimensional, thermal-electrical- optical self-consistent model of the gain-guided vertical- cavity surface-emitting laser (VCSEL) is applied to study behavior of its transverse modes. Many intensity maxima of higher-order modes were found to disappear because of a complex interplay between a real guiding effect and a gain antiguiding effect in VCSEL resonators. Therefore number of intensity maxima in experimental intensity profiles can not be used as an indicator of the mode order. Radiation losses of transverse modes were found to increase with an increase in their order.

We propose an efficient method of cooling atoms in a strong Gaussian standing wave. The steep gradients of the atomic potential energy give rise to large dipole forces, which can be much stronger than the maximum radiation pressure force and can therefore stop atoms in a much shorter distance. We have simulated the cooling process using a semi-classical Monte- Carlo method, which includes the radial motion, in addition to the motion along the beams. Both motions are calculated directly without separation the dynamics into force and diffusion terms. To cool a large range of atomic velocities the frame in which the standing wave is at rest was swept by changing the frequencies of the counter-propagating beams, in a similar way to the well-known chirp cooling technique using the radiation pressure force. If the curvature of Gaussian beams far from beam waist is employed the radial motion and velocities can be reduced even for the blue detuning comparing to the near waist case. The simulations show that it is possible to stop caesium atoms in a distance of several centimeters (the exact value depends on the laser power, beam waist radius and acceptable chirping force) starting from the most probable velocity at room temperature. Narrower radial and wider axial velocity distribution was obtained for red detuning comparing with the blue one.

Force exerted on a micro-object by the focused laser beam can be as high as the gravity force acting on the object or even significantly higher. This implies that the laser light can be used to manipulate small objects (range size approximately 0.1 - 100 micrometer) within suitable immersion medium. This possibility is of a great practical importance, for example, for microbiology and molecular biology (manipulation with single living cells, cell organelles, chromosomes, etc.) as well as for micromachinery and other technical branches. We use a ray-optics-based model to determine the magnitude of forces exerted by laser light as the functions of laser beam, object and surrounding medium parameters. We study the influence of these parameters on total force in order to find the optimal parameter combination for the most effective manipulation. We have employed these theoretical results in practice and succeeded in building up a 3-D laser trap which we use to manipulate divinylbenzen spherical particles (10 - 35 micrometer sized) and also irregularly shaped living protozoa cells in water medium.

At application of laser welding the determination of parameters of laser beam and its kinematics is desirable. For laser spot welding of thin metal materials a model of estimation of these parameters is presented. The task is solved on basis of one-dimensional model of melting of metal as a semi-infinite body with fixed thermally-physical properties. The model is applicated on a concrete example of laser welding of pacemaker housing being made from titanium sheet with thickness of 0.5 mm.

The iodine-stabilized He-Ne lasers are the wavelength standard for metrology of lengths in mechanical engineering and microelectronics today. The high accuracy of the frequency of this standard predetermines this laser to be the fundamental etalon for laser interferometry. In the contribution, a novel approach to design of a control He-Ne-I₂ electronics controlled by a PC computer is presented. During tuning the iodine spectrum can be monitored and frequency locking to the hyperfine lines is automatized. A general diagnostic via the computer is also available. The main aim of the design of a new electronic control unit was the attainment of a better noise suppression, higher reliability and better user comfort during operation. The design exploits the experience of using the first electronic system designed at the Institute of Scientific Instruments by B. Popela and his co-workers. The new stabilizing system is computer controlled, all functions are accessible only via the computer. The computer graphics of the PC gives an excellent opportunity of a highly comfortable operation. A simplified schematic is shown in figure 1. The control part consists of an interface, communication circuitry and data conversion, and switch controller. All the logic is of low consumption HC type and is galvanically isolated from the analog part. Data communication between the controller and digital-to-analog and analog-to-digital converters is executed through high-speed optocouplers.

The mutual interference of two beams in the spectral domain has been demonstrated experimentally at the output of a Michelson interferometer excited by two low-coherence sources which differ substantially from each other by the width of the spectrum, and whose coherence lengths are shorter than the optical path difference (OPD) between both beams. The spectral interference between two beams, which shows up for the first source the wavelength-independent and for the second source the wavelength-dependent periodic modulation of the source spectrum, serves as an illustration of the feasibility of an experimental method utilizing a high-resolution spectrometer in the evaluation of the group OPDs and displacements in a range dependent on the source spectral width. A cross- correlation procedure between the experimental and theoretical spectral modulations has been applied in the estimate of the group OPDs as well as in the evaluation of their wavelength dependence affected by dispersion of the beamsplitter. Moreover, good agreement between theoretical description of two-beam spectral inference experiment and the measured spectral modulation has been confirmed and the effect of both the spatial and the spectral integration has been resolved.

The mutual interference of two linearly polarized (LP) modes in the spectral domain has been demonstrated experimentally at the output of a two-mode optical fiber excited by two low- coherence sources which differ substantially from each other by the width of the spectrum, and whose coherence lengths are shorter than the optical path difference between both LP modes. The spectral interference between two LP modes, which shows up for the first source the wavelength-independent and for the second source the wavelength-dependent periodic modulation of the source spectrum, serves as an illustration of the feasibility of a novel experimental method utilizing a high-resolution spectrometer in the evaluation of the spectral dependence of the group optical path difference between both modes. Moreover, it has been shown that the spectral analysis performed across the output modal pattern of the two-mode optical fiber leads to spectral modulations in which the effects of both polarization properties and overlaps of both LP modes are inscribed.

Theoretical background of a heterodyne interferometer to measure linear displacements of a rough surface is presented. The surface of a sample is illuminated by two laser beams having mutually slightly shifted frequencies by using acousto- optic modulators. The essential parameters of the system measuring in-plane and out-of-plane displacement are discussed.

One of the oldest and simplest techniques for determination of thin transparent film thickness is based on evaluation of the interference colors produced by the film. Even if its accuracy is limited and technique itself has been overcome by many advanced techniques it still plays non-interchangeable role in observing the moving thin fluid lubricant films. a computer- aided system for reconstruction of thin fluid film shape from chromatic interference fringes is presented conceptually and the parts of system are demonstrated. Quasistatic fluid films were generated in an experimental equipment working as a two- layer Fizeau interferometer. Chromatic patterns produced by Tolansky method were photographed and digitized. The CIELAB color difference equation was used for comparing interferograms with the digital color chart to determine the fluid film thickness. Three-dimensional mesh surface plots of film shape with high film thickness resolution were generated using techniques of image processing and computer graphics. The limitations and accuracy of the proposed system are discussed and its validity was checked by observing lubricant capability to create coherent lubricant film under various conditions.

In the paper an analysis of a fringe pattern field with an observation of a chosen fringe course, for defining the profile of refractive index of planar waveguides are proposed. With an application of the measuring method described, refractive profiles of planar waveguides, produced in the soda-lime glass by means of an ion exchange Ag⁺ $ARLR Na⁺ were examined.

This paper contains selected experimental knowledge obtained by the quality control of composite materials and by the confronting their poverties with a theory of composites. This piece of knowledge can be used for the creation of design for new products' construction solution. At the same time it can be applied also to view the alternatives for the utilize of these materials according to really gained quality degree.

With respect to the future investigation of asymmetrical types of transparent objects such as plasmas, air and fluid flows, the autor aim was to develop and test an optical set-up which allows a tomographic study of stationary inhomogeneous phase objects on the basics of holographic interferometry along with two mathematics methods of transmission computed tomography (TCT) in order to obtain three dimensional distribution of the index of refraction and temperature. For this two TCT methods -- convolution backprojection method and orthogonal polynomial method -- were used in our experiment with a flame as a testing object. We modified the set-up based on a Mach-Zehnder interferometer, which enables us to use only one holographic plate and low power laser.

The paper presents preliminary results of applying two different interference techniques for evaluation of the breakup characteristics of the tear film. The Twyman-Green interferometer (TGI) and Lateral Shearing technique (LST) were applied in two separates set ups. To find irregularities in the tear film distribution, the sequence of interferograms of the cornea or contact lens were stored and processed in a computer by use of modular frame grabber. The interferograms of in vivo precorneal tear film breakup formation are presented for both techniques. The proposed methods have the advantage of being noncontact and applying the low energy laser beam.

We have applied imaging polarimetry to measure birefringence of the human cornea in vivo. A theoretical model of the corneal birefringence is considered. The polarized light transmission through the system is modelled theoretically by use of the Jones matrix formalism. The light passes some polarization components, the cornea, anterior chamber and is scattered at the iris. Using computerized polarimeter, two maps representing distribution of the azimuth angle and retardation are calculated and presented. Investigation of the corneal birefringence could be useful for examining the inner corneal structure, its lamellar arrangement and in medical diagnosing of keratoconic cornea.

Side-hole fibers are one of the most hopeful types of fibers applied in pressure measurements. They have high sensitivity to pressure due to the presence of two air channels placed symmetrically near the circular or cylindrical core. In this paper, results of research of side-hole fibers with elliptical core are presented. The beat lengths of these fibers as well as the pressure and temperature sensibility were measured. The pressure sensibility reached 150 rad/MPa(DOT)m for the most sensitive fiber; that is a value 15 times greater than the sensitivity of standard birefringent fibers. Relation between the pressure and temperature sensitivity seems to be hopeful also, because their quotient was about 100 K/MPa for most of examined fibers.

The influence of aberrations (spherical aberration and wavefront tilt) of the optical system of a Fourier transform infrared spectrometer (FTIR) spectrometer on the measurement precision is presented. The computer simulation of the Michelson interferometer operation has been performed. Two cases are considered. In the first case an aberrated wave was introduced in the movable arm only, while in the second one the aberrated waves were present in both arms. Successively the Fourier interferogram at the detector plane was obtained vs. displacement of the interferometer mirror, and the fast Fourier transform was applied to recover the original spectrum. The spectrum distorted by aberrations was compared with the results of the ideal spectrometer to determine errors introduced by imperfections of the optical system.

For many applications of the fiber couplers such as coherent detection in fiber telecommunications or fiber sensing, the main parameter, the energetic coupling ratio, is not enough to describe properly the propagation properties of the fiber coupler. We found the analysis of the laser beat signals as useful technique for diagnostics of the optical fibers and fiber couplers.

A diffractive element which generates annular light source is investigated from the point of view of its area optimization. In the paraxial approximation, the zones distribution of such an element can be described by a double parabola. As the zone areas of this element are not the same, the equalization of first two zone areas is proposed in order to improve the diffraction efficiency.

The design of a set of filters reshaping collimated Gaussian beam into that with uniform intensity profile is based on the energy conservation law and the geometrical optics. The diffraction effects neglected during design process are evaluated using the boundary diffraction wave. An amplitude distribution at the plane of the second filter and the correction of the second filter, which collimates the beam after energy redistribution, are calculated.

The properties of laser induced stationary phase gratings arising through the process of thermal energy deposition have been studied. We present our results dealing with the influence of various grating parameters on the energy of the first non-Bragg diffraction beam.

The possibilities of aberration correction in the case of a single lens are limited. It is well known that, if classic glasses are used, it is impossible to compensate spherical aberration. It can be, however, minimized by proper choice of the ratio between the first and second surface radii of curvature (referred here as (zetz) ). It is possible also, in cost of uncorrected spherical aberration, to compensate III order coma. Additional possibilities of aberration correction occur, however, if a thin diffractive structure is deposited on one of the lens surface. Such lens is usually referred as a hybrid (diffractive-refractive) lens. The diffractive structure typically corresponds to the holographic lens generated by the interference of two spherical waves. The ratio of these waves radii of curvature is treated as a parameter (called here (beta) ) describing fully aberration properties of this structure. A focusing power of the diffractive part typically is only a small fraction ((eta) ) of total focusing power of a hybrid lens, so the diffractive part acts mainly as aberration corrector. Aberration properties of hybrid lens are determined by two parameters: (zetz) and (beta) so it is possible to achieve simultaneous correction of aperture aberrations: spherical aberration and coma. In the paper formulas describing the III-order aberration coefficients were used for calculating the values of parameters (zetz) and (beta) assuring such correction for several values of parameter (eta) and different locations of object plane. The calculations were performed with help of the MATHCAD programme. Basing on the results a number of hybrid lenses (collimating and imaging) were designed. Their imaging quality was then evaluated by numerical calculation of aberration spots. Estimated values of such image characteristics as the aberration spot moment of inertia or third order moment of the spots distribution enable to compare the imaging quality.

Diffractive optics is more and more widely used nowadays. One of its most important applications is diffractive imaging element (DIE). The DIE can be a lens (Holo-lens, diffractive lens, hybrid lens) or a part of complex imaging system (e.g. an aberration corrector). Apart of such problems occurring when dealing with DIE as its design, manufacture or copying the problem of its control is important. By this we mean the measurement of wavefront generated by DIE, i.e. the evaluation of wavefront aberrations. To this aim we propose two different experimental methods: one of them employs diffraction interferometer, the other one holographic shearing interferometer.

The matter of the analysis are coated plane-parallel plates of BK7 glass and Nd:YAG microchip lasers illuminated with coherent beam. Short wave and long wave absorption bands and dispersion of refractive index of glass have been omitted to simplify the problem. There are analyzed multilayers designed for visible or IR range. Analyzed examples can be easily generalized to other substrates, layers' materials and wavelength.

Mn discontinuous films with different mass thicknesses d (4 nm - 32 nm) were evaporated onto quartz-glass substrates under vacuum condition (p equals 10^-6 Torr). The coefficients of reflection R (from the air-side) and transmission T at normal incidence were measured in the wavelength range from 200 to 3500 nm. Using Wolter's approximation, the imaginary part of the effective dielectric permittivity (epsilon) '₂ was determined in UV and visible. The microstructures of the films were examined with electron microscope. It has been found that optical properties of thicker, continuous films (19 nm less than or equal to d less than or equal to 32 nm) are typical as for the metallic phase, high reflection coefficient values in visible and infrared range, minimum of reflection at (lambda) equals 250 nm. In the case of thinner films (8 nm less than or equal to d less than or equal to 13 nm) maximum of reflection coefficient and imaginary part of dielectric permittivity occur in UV ((lambda) approximately equals 300 nm). These peaks may be attributed to resonance effects connected with island, discontinuous structure of the films. For the films with thicknesses d less than or equal to 6 nm maxima of R and (epsilon) '₂ vanish and optical properties became typical as for the dielectrics, the transmission coefficients reach high values in visible and infrared range. The results of structural examinations are also presented.

On the basis of the previous structural and electrical examinations it has been found that thin, especially discontinuous Mn films even under vacuum conditions are quickly oxidized. In order to protect from this process just after evaporation of Mn films, its were in vacuo covered with MgF₂ layers. The influence of MgF₂ dielectric layers with thickness d_d approximately equals 21 nm on the optical properties of Mn films was investigated. The thicknesses of Mn films varied from 4 to 32 nm. Optical properties of double films (Mn + MgF₂) differ distinctly from those of single Mn-films. Dielectric layers with thickness d_d approximately equals 21 nm protect from oxidation process and cause an increase of reflection coefficients and decrease of transmission coefficients in the visible and infrared range.

Optical properties of vanadium films have been investigated. Based on the measurements of reflection coefficient in 0.2 - 50 micrometer spectral range the optical constants of vanadium films were determined using Kramers-Kronig dispersion relations. Using the optical constants for a wide spectrum the electrical microcharacteristics of vanadium films were determined. Assuming the normal skin effect the electron collision rate and plasma frequency were calculated. The concentration of conduction electrons has been also determined. Making use of knowledge of resistivity in room temperature and in the temperature of liquid helium the electron-photon and electron-impurities collision rate contribution to the effective conduction electron collision rate has been estimated.

The magneto-optical effects in reflection are often used for the investigation of the in-plane magnetization behavior in thin ferromagnetic films. The methods of the magneto-optical hysteresis loop measurements are presented for both magnetization components parallel and perpendicular to the external magnetic field. The influence of the longitudinal and the transverse magnetization on the reflection coefficients including the second order magneto-optical effects is presented. The formulas for the reflection coefficients and the magneto-optical angles are brought for the interface between an isotropic medium and a cubic magnetic crystal with the in-plane magnetization. The Yeh's 4 by 4 matrix formalism, based on eigen modes propagation in the anisotropic magneto- optical medium, is used for the calculation. The theory is introduced for the epitaxial Fe film evaporated on MgO substrate for the field along a magnetically hard axis. The second order effect of the transverse magnetization component suprposes on the linear longitudinal Kerr effect. This undesirable second order effect can be attenuated by choosing the optimal magneto-optical quantity and the measurement geometry. On the other hand the normal incidence geometry is optimal for investigation of the second order magneto-optical effects, because the linear longitudinal and transverse Kerr effects disappear. The pure second order hysteresis loops are measured in this geometry. There is the reflection analogy of the Voigt or the Cotton-Mouton geometry.

A new procedure for depositing three-layer structures [doped metal oxide/metal/metal oxide (In₂O₃/Ag/TiO₂)] on a glass substrate by applying different methods of film deposition was developed. To obtain the first film -- In₂O₃:Sn, the spray hydrolysis method was employed and for the second, a thin Ag film, the vacuum evaporation technique was used. The third film -- TiO₂ was obtained by the organic oxide compound polymerization method. The electrical and optical properties of the films and the multilayer structure thus obtained were investigated. The studies showed that the three-layer structure could be used as a broad-band infrared filter.

Single frequency generation was investigated in two types of diode pumped lasers: microchips and lasers with metallic thin film selectors. Principles and properties of both types of single frequency generation are discussed. Energetic output characteristics, spectra of generation, tuning ranges were measured and compared for both lasers. In case of microchips only Nd:YAG crystal was applied, whereas in case of metallic thin-film selector single frequency output was achieved in Nd:YAG, Nd:YVO₄ and Nd:YLF crystals. Up to 50 mW of power at single frequency in Nd:YAG microchip and 600 mW in Nd:YVO₄ laser with selector were obtained. Physical and technical limitations caused by the wide gain bandwidth, thermal effects and mechanical vibrations were discussed.

A submicroscopic surface roughness as well as the atomic scale roughness are required for the observations of the strong SERS signal. The submicroscopic roughness is necessary to occur the electromagnetic enhancement of Raman scattered light, whereas the atomic scale roughness, i.e. the existence of the 'active sites' on the surface, plays the crucial role in the chemical enhancement. Accordingly to the prediction of electromagnetic model (EM), the SERS intensity depends on the size and shape of grains forming the rough surface. Additionally, as it predicts the chemical model, the SERS intensity depends on the concentration of 'active sites' on the surface. The performed investigations of the SERS intensity dependence on the variations of roughness, confirm the EM model. On the other hand, the observed correlation between the changes of SERS intensity and the changes of intensity of reflected light seems to prove that the SERS-active surface exhibits the absorption band associated with the charge-transfer transition within the complexes active site-adsorbed molecule.

We developed a novel finite-difference vector beam propagation method for three-dimensional waveguide structures. The method uses a vector electric field propagating in an inhomogeneous medium under slowly varying envelope approximation. The form birefringence and the coupling between transverse field components are taken into account. The scheme proposed for solving coupled paraxial vector wave equations is based on the operator splitting technique. The resulting algebraic equations are tridiagonal. The method is stable and very efficient.

In this paper the problem of athermalization is considered. We assume that the both mechanical and optical parts of the device has its actual structure divided into separate housings. Two variants of passive and active athermalization is taking into account. We present also our results with computer-aided athermalization program.