This report shortly describes calculation method related to guiding properties of the microstructure fibres. For the
modelling of wave propagation in such fibres in linear and nonlinear regimes the finite-difference vectorial-beam-propagation
method (FD-VBMP) has been chosen. This method offers high accuracy and allows investigating
longitudinally varying structures or propagation of optical waves with amplitudes varying under the effect of nonlinearity
and loss. In order to take into account the effects related to the finite fibre dimensions the transparent boundary
conditions (TBC) was used. The Split-Step Local Error method is implemented for correct estimation of the influence of
nonlinearity on the wave propagation in microstructure fibres. On the basis of this method the complete algorithm for the
numerical simulation of the wave propagation in microstructure fibres under the effect of nonlinearity has been
developed. The method allows optimising the structure of photonic crystal fibres (PCF) for maximising or minimising
nonlinear effects. Investigation of the properties of a wavelength converter based on a microstructure fibre was carried
out using simulation results in the nonlinear case. Modification of the method for optimisation of connection between
microstructure fibres and conventional fibres is also considered.
We propose the method of all-optical performing the operation of matrix multiplication on the base of the matrix of waveguide ring microresonators. Information is processed immediately when it passes through the optical system, which performs the computation procedures, and with supply of the input data in parallel. The speed of such optical matrix processor is mx1010 vector multiplication per second, where m is the quantity of the used wavelengths that defines the number of rows of the multiplied matrix.
We propose the method of calculation of the dispersion characteristics and field distribution of the modes in straight and bent multi-core microstructured fibers. The method is implemented for the analysis of the birefringence in dual-core microstructured fibers in dependence on the fiber parameters (air hole diameter, hole separation, distance between guiding cores) and bend radius. The term "birefringence" we understand here in the wide sense including both the difference of the parameters of orthogonally polarized modes (polarization birefringence) and the difference of the parameters of two supermodes with identical field distribution propagating in dual-core microstructured fibers (supermode birefringence). The optimization of the parameters of such fibers using as vector bend sensors is considered.
The results of physical process investigation of three classes of nanoelectronic devices, such as 1) single-electron tunneling (SET) devices, 2) resonant-tunneling structures (RTS's), 3) quantum wire (QW) devices are described in the paper. The single-electron 1D and 2D arrays, resonant-tunneling diodes (RTD's), interference T-transistors and quantum wires were simulated. Analysis was carried out for different material parameters and structure design. The main
regularities of physical processes depending on mentioned parameters, applied voltage, temperature for devices from different materials are described. To simulate new models of SET devices of semiclassical approach which takes into account the influence of spatial quantization due to transversal dimensions and co-tunneling effect were used. In the framework of semiclassical approach and wave function formalism we considered scattering by different mechanisms in model to simulate various RTD's. Different scattering mechanisms can be taken into account for simulation of QW devices with the use of the Wigner-function formalism models. All new models have been included in simulation system of nanoelectronic devices NANODEV [1]. In the paper the results confirming the adequacy of the developed numerical models including a comparison with experimental data are presented. All investigations were carried out by PC on the base of Pentium-III processor.
The results of physical process simulations for different structures of resonant-tunneling diode (RTD) are described in the paper. One-band [1,2] and two-band combined numerical models of RTD are involved in investigation. Two coupled Schodinger equations are solved in two-band combined model. It allows to consider Γ-X intervalley scattering influence on electron transport in RTD. The developed one- and two-band models permits to take into account of charge influence in different regions of device, including surface charge, classical and quantum-mechanical regions interaction, shape of energy-band offset on heterojunctions, other scattering mechanisms, resistances of near-contact regions. The models allow to simulate RTD with arbitrary number of barriers and calculate have functions, charge and potential distributions, transmission and IV- characteristics depending on different material parameters and structure design. The proposed models have been included in numerical simulation subsystem NS-RTS-NANODEV, which is a part of nanoelectronic device system NANODEV. In the paper the comparison of simulation results carried out with the use of proposed one- and two-band combined models of RTD are presented. It allows to verify significance of Γ-X intervalley scattering for some material systems in a number of cases.
The structure of an electro-optical modulator is proposed which permits to overcome the limitations imposed by the parameters of control channel. The basic components of the modulator are electrically controlled fiber Bragg gratings. The proposed structure makes possible to obtain the modulation of optical radiation with double frequency compared to other modulators with the same electronic control circuits. In the paper we calculate the modulation characteristics of such modulator, consider the different conditions of it operating and estimate the possibility of farther increasing the speed of modulation by optimization of the parameters of fiber Bragg gratings. The proposed device is compact and well interfaced with optical fiber links.
The effect of influence of different material parameters and structure design on IV-characteristic of RTD is considered in the paper. Special attention was paid to analysis of the interaction between classical and quantum-mechanical RTD regions. The combined numerical model of a resonant-tunneling diode, based on self-consistent solution of the Schroedinger and Poisson equations is presented. The interface charge was added to the Poisson equation and its approximation is also given. The simulation of IV-characteristics of RTD on In0.53Ga0.47As/AlAs and GaAs/AlAs was carried out by using the combined model and model modifications. As a confirmation of accuracy and adequacy of the proposed model there was achieved a good agreement between theoretical and experimental results. The effect of interface charge and sizes of the active regions on IV-characteristics of RTDs was also studied.
The basic parameters of optical logic elements AND with three inputs are estimated. The logic elements are based on complex fiber Fabry-Perot resonators, formed by two Bragg reflectors and one end mirror. Such a logic element producing of half-adder in a one switching tact can be used for algorithmic acceleration of optical computing. Considered optical logic elements can be used for preliminary information processing in fiber interconnections between chips or blocks of computing systems.
The architecture of parallel optoelectronics adder, in which the spectral compression corresponding to inputs permits to accelerate algorithmically optical data arrays processing, has been developed. This approach excludes galvanic connections corresponding inputs/outputs and make it possible to perform parallel computation in a wide frequency range.
The structure of controlled optical fiber processor for operation of matrix/vector multiplication is proposed. Such processor could be used for calculation of large data stream in optical image and information processing. The processor consists of an array of elementary processors. Each elementary processor is a combination of an optical amplifier and coupler. The algorithm of processor operation is discussed.
The method of enhancing the information capacity and reliable storage of information in circulator fiber-optic memory is presented. The method is based on creation of an additional built-in channel with contrary-directed circulation of signals. This channel can be used for transmission of both information and auxiliary signals: address words, clock signals, correcting sequences, etc. The possibility of compensating the information signal losses by means of stimulated Raman scattering is considered.
The method of enhancing the information capacity and reliable storage of the information in circulator fiber-optic memory systems is presented. For this purpose the additional channel with contrary directed circulation of the signals is provided. The additional channel is simultaneously used for circulation of the clock signals and for compensation of the information signal losses in optical fiber due to stimulated Raman scattering.
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