Paper investigates various optical link simulation programs that can be used in different teaching courses. Web-based educational materials became popular because these resources can be accessed by anyone who has access to the World Wide Web. In this paper, we will review software that deals with the simulation of optical communication systems. The main advantages of embedding this kind of software into teaching courses consist of opportunity to experiment and to research by using simulation. Students can experiment with different facts and test the system which may otherwise require a large and an expensive setup of laboratory equipment and at the same time making the theoretical courses more interesting to learn.

The approach to creation of the device ensuring function of switching, independent of the protocol, is considered. The device is of interest with construction completely of optical networks. The task of a presence of an interference picture in the complex profile resonator of a Fabry-Perot type is decided. The decision is carried out by numerical integration of the wave equation of the second order, and also developed simplified methods. The simplification allows to integrate the equation of the first order. The result for resonators of length up to 200 microns is received.

There are two main approaches for the enhancement of data transfer rates in fiber-optical communication systems: by increasing the number of WDM-channels or simply by increasing the bit rate of each channel. At present, a key factor which restricts the date rate of WDM-channels is polarization mode dispersion (PMD). PMD has a significant influence on the signal quality at bit rates of more than 10 Gbps per channel. An adaptive optical compensator based on controlled birefringent elements for mitigation of higher order PMD is posed a challenging method. Using the EMTY model in combination with nonlinear optimization to adjust the compensator parameters leads to good results (in given test - average PMD value is reduced about 2,5 times) and can be used as basis of an algorithm for a reconfigurable optical compensator.

Simulation results of a few-mode signal propagation over multimode fiber link, been excited by laser source, are represented. The link includes conventional multimode fiber with graded-index profile, and differential mode delay (DMD) compensating multimode fiber, been installed at the receiver end. A real refractive index profile samples of different fiber generations, been measured by analyzer EXFO NR-9200HR, are considered as prototype of link fiber. Recently proposed so-called reverse DMD fibers (RDMDF) are applied to compensate mode delay. Here DMD compensation is based on following effect: the initial array of excited mode group velocity diagram is reversed in reference to the fastest mode. This effect is obtained by synthesis of special graded profile, based on optimization with objective function, been represented as a sum of squares of deviations between points, corresponding to radial mode orders, of ideal desired reverse group velocity diagram and diagram of current iteration. Time-domain model of piece-wise regular multimode fiber link is applied to simulate laser excited a few-mode pulse propagation. The model takes into account DMD and higher-order mode chromatic dispersion. Results of pulse dynamics calculation during propagation over described multimode fiber link under DMD compensation effect are represented.

In this paper influence of DDMS dispersion segment deviations from nominal values on system performance was investigated. The model of dispersion managed soliton propagation based on variatonal approach was used. The results of statistical simulation of soliton-like pulse propagation in optical communication lines with different dispersion maps and taking into account deviation of dispersion map parameters are represented.

Chromatic dispersion characteristics of dispersion compensating fibers with arbitrary shapes and index profiles are calculated by using a finite element method. A vector finite element method with mixed interpolation type triangular elements implemented. The approach uses optimized way of global sparse system assembling which is considerably reduces calculation time. Different types of mesh formation examined for better resolve of the dielectric interface boundaries. Features of the algorithm are demonstrated by examples of calculation for microstructured fibers. The correctness of assessments confirmed by comparison with those of known solutions and experimental data.

Pre-design researches on creation of the built in parachute parameters monitoring system which can be used both at a stage of its tests, and at stage of its control for the purpose of its characteristics management are resulted. Fiber optic sensor on the basis of two twisted fibers with the locked ends offered by us for this purpose does not demand lamination, indifferent to a thermal (temperature) field, provides a wide dynamic range of measurement as pressure and tension of parachute elements.

For carrying out of measurement of refractive index of new materials and research of nonlinear effects use of the Mach-Zehnder interferometer is offered. In action principles of all interferometers are identical, they differ only in the way of coherent waves reception. Mach-Zehnder interferometer is one of Zhamen interferometer versions. Advantage given interferometer is that the distance between ways of distribution of coherent waves can be made as much as big. In given article results on stand working out on base of Mach-Zehnder interferometer for exact definition of refractive index of optical materials are presented.

Errors of optical fiber chromatic dispersion calculation caused by line approximation of silica glass refraction index as a function of dopant concentration are investigated. Calculation of chromatic dispersion for fibers with refractive index profiles, for which experimental data of chromatic dispersion are known, is performed by an investigated method. Errors of chromatic dispersion calculation are estimated by deviation evaluated results from data of measuring for samples of optical fiber. On the basis of the comparative analysis the estimation of adequacy of the cosidered method is given.

We discuss the propagation of monochromatic light vortex beams in a medium with minor nonuniformities of the refractive index. The propagation of the light beams is modeled by two methods - using a paraxial integral operator and through the decomposition in the parabolic medium modes.

Comparative results of guided mode bandwidth parameter estimation are presented. We considered profiles of conventional silica GeO2-doped multimode fibers 50/125 both with quasi-optimal smoothed form and with different deviations from the optimal α-profile, including central defect and local refractive index fluctuations, occurring in real fibers. Defects of profile were reconstructed from the samples, been measured by fiber analyzer EXFO NR-9200HR. Fundamental and higher-order guided mode bandwidth parameters were calculated by modified Gaussian approximation. Some fiber samples were analyzed both by proposed approximate method and rigorous vector finite element method, adapted for multimode graded-index fiber, to estimate the error of modified Gaussian approximation. Results of data comparison, been obtained both for optimal α-profile and under particular defect type, are represented.

A device for conversion of single frequency signal into two-frequency signal, based on lithium niobate dual-drive Mach-Zehnder modulator was proposed. The output spectrum was obtained analytically the proved numerically. The conditions for two-frequency signal generation were described.

A design of controlled diffractive optical elements based on electro-optic effect was suggested. An influence of the electro- optical crystal orientation, the direction of light wave propagation and the electric field distribution on the characteristics of controlled diffractive optical elements was considered. The efficiency indicators of controlled diffraction elements structure and material were proposed and their values for the basic elements were calculated.

In article the algorithm of numerical modelling of the nonlinear equation of Korteweg-de Vrieze which generates nonlinear algorithm of digital processing of signals is considered. For realisation of the specified algorithm it is offered to use a inverse scattering method (ISM). Algorithms of direct and return spectral problems, and also problems of evolution of the spectral data are in detail considered. Results of modelling are resulted.

Maximum permissible opportunities of laser photo-electronic aerosol spectrometers using modulating measuring techniques are analyzed. The ways of accuracy and measuring transformation range improvement accounting achievements of non-modulating and interferometer techniques are discussed. Two intra cavity modulating techniques based on scanning of the cavity flat mirror and on synchronization of the laser transverse modes are submitted.

We propose and analyze a new optical system to transform the (most characteristic) linearly polarized laser modes into axially symmetric (radial or azimuthal) modes, which show more promise in various applications, as well as generating various inhomogeneously polarized configurations. The system is based on the coherent composition of the modal beams with use of phase diffraction gratings, which allow the inter-mode phase shift to be varied without resort to auxiliary components. What makes the system simple and universal is the use of diffraction gratings to generate required mode patterns with specific space orientation alongside the simultaneous generation of different beams with different transverse mode content, which can subsequently be combined.

The article presents the results of investigation regarding the optical fibre fastness to bending with permissible tensile load and bending stiffness at the closure output depending upon the port sealing method of the fibre optic closure.

Most common types of fiber optical sensors (FOS) and their applications in monitoring of civil building are analyzed in this paper. The new sensor based on twisted optical fiber with closed ends and varied twisting step is designed. The mathematical modeling of the sensor and a number of experiments to investigate its characteristics, including the sensitivity, were realized. The method of frequency incoherent reflectometry was proposed to use in order to collect information from FOS. Data acquisition software was designed.

In this paper method and equipment for estimation of polarization mode dispersion distribution along optical communication lines are represented. The polarization optical time domain reflectometer with linear extension of pulse width is described. The measurement algorithm and data processing algorithm are shown. The prototype model of PODTR was developed.