The theoretical and experimental studies of statistical properties of the input signals of optical electronic systems were carried out. The statistical models of interaction of an optical signal in optoelectronic systems based on the the distribution laws, characterized by a finite and infinite dispersion, were developed. The study of the asymptotic behavior of tailings of the output signals distribution densities for optoelectronic systems proved the possibility of using stable distribution laws describing the source signals of optoelectronic systems. The boundaries of statistical models applicability were outlined based on the central and generalized boundary theorems. Theoretical and experimental researches with the provision of high accuracy of determination of signals spatial-temporal characteristics with increased probabilistic detection characteristics were presented.
The paper presents the analysis of the influence of elongation of stainless steel and aluminium samples on the response of uniform fiber Bragg gratings used as measuring transducers. Research indicates the possibility of material type and material thicknessing on the basis of transmission spectra obtained with the use of a periodic structure. During the research, deformations of transmission spectra were noticed. These defects may be the result of the glue connection used for assemble the periodic structure to the sample. The results of the research were presented in the form of charts obtained on the basis of transmission spectra.
The article presents the possibilities of detecting defects in steel material using the fiber Bragg gratings (FBG). Measurement of sensitivity to force change is ensured by shifting the FBG. Steel samples were used for the tests: one standard sample and the others were incised. The incisions were at right angles and sharp to the axis of the fiber. The FBG was glued to the sample along its entire length and then lengthened by force. The transmission spectrum was being obtained on the Optical Spectrum Analyzer (OSA). It was used to determine the processing characteristics: the main minimum on the transmission characteristics and the full width at half maximum (FWHM) depending on the force transferred. On the first characteristic, the quantity of incisions can be detected (for a larger amount of incisions the main minimum changes significantly), and on the second characteristic, both the quantity of incisions (the greater the number of incisions the FWHM change is greater) and the approximate angle of incision relative to the fiber axis, FWHM decreased during increasing forces in the case of a right angle, while it increased in the case of an acute angle.
The paper clarifies neurocomputer and neurocomputer architecture term definitions. The choice of spiking neural network as neurocomputer operating unit is substantiated. The spiking neurocomputer organization principles are formulated by analyzing and generalization of the current level of knowledge on neurocomputer architecture (based on analogy with the well-known von Neumann digital computer organization principles). Analytical overview of current projects on spiking neural networks hardware implementation is conducted. Their major disadvantages are highlighted. Optoelectronic hardware implementation of spiking neural network is proposed as such that is free of mentioned disadvantages due to usage of optical signals for communication between neurons, as well as organization of learning through hardware. The main technical parameters of the proposed spiking neural network are estimated.
The principles of construction of various types of spectrometers used for x-ray fluorescence are considered, their advantages and disadvantages are analyzed. An approach to the implementation of the wavelength dispersive spectrometer is proposed, which allows to reduce the time of spectral analysis in the entire range of the x-ray fluorescence.
This paper presents the results of experiment determining the dependence of shift in spectral characteristics of Bragg gratings as a function of energy supplied to the optical fibre in the process of producing optical fibre periodic structures. The experiment was performed in an excimer laser system for two optical fibres with different photosensitivity.
The paper specifies the achievable Bragg wave shift generated by pre-stressing the optical fibre in the phase mask writing process. The maximum possible shift results from the mechanical strength of the optical fibre to axial stress. Two methods are also proposed for the production of Bragg gratings with a controlled Bragg wavelength. The experiment was performed for the SMF28 fibre subjected to the hydrogenation process. The FBG fabrication was carried out in the excimer laser system using the phase mask method.
A new analytic parameter-the degree of local depolarization (LPD) of the laser field-is theoretically justified. The technique of experimental measurement of LPD maps is presented. Sets of diagnostic parameters-statistical moments of the first-fourth order, the correlation area and the variance of the logarithmic distribution of the LPD power spectra are obtained. Differential diagnostics of rat skin carcinoma was realized.
The article deals with the development of a multifrequency phase method for measuring the range and radial velocity of targets. It is shown that to measure the distances of targets it is necessary to measure the amplitude and phase characteristics by envelope of the spectrum of the probing signal, and to measure the radial velocity - the measurement of the Doppler shift of the spectral components at the intermediate frequency.
This paper presents the spectral properties of chirped tilted Bragg gratings (CTFBG) written on photosensitive optical
fiber by using phase mask technique and excimer laser. The dependencies of manufactured structures spectra on three
various values of chirp: 0,1 nm/cm, 1 nm/cm, 10nm/cm and gratings tilt angle in 0° to 2,5° range with 0,5° change have
been shown in all combinations. Influence of temperature changes in -40°C to 180°C range on measured spectra have
been investigated. We showed the dependencies of CTFBG spectral parameters in various cases of periodic refractive
index variations angle and different chirp values given in manufacturing process.