1. The xecl laser with the adjustable shape and duration of generation pulse
S.S. Anufrik, A.P. Volodenkov, K.F. Znosko
LC- contour, XeCl laser, excitation system, generation energy, pulse duration.
Vestnik KhNU ¹983 Pages. 3-10
The generation parameters of LC-contour excitation system are studied for electro-discharge excimer XeCl laser using a Ne–Xe–HCl mixture. A computation model is developed for finding the generation parameters. It has allowed us to calculate current, voltage and generation power oscillograms for all parameters of the electrical excitation system. The program of XeCl-laser modeling enables to calculate an electrons, atom and molecule concentrations, specific energy deposition in active medium also. By means of program Bolsig + calculation of rate coefficients of reactions with participation of electrons is executed. It is shown that generation of short radiation pulses (20 ns) and relatively long pulses (60 ns) is possible due to changing of LC- contour parameters. Energy of generation reaches a maximum at use of small values of peaking capacity, which are significantly smaller then value of storage capacity.
laser radiation, acoustic emission, plasma, crater, a zone of non-elastic destruction, laser-plasma evolution.
Vestnik KhNU ¹983 Pages. 11-17
Acoustic emission of a zone of the destruction formed during influence of pulse laser radiation on a surface of metal is considered. Dependence of the time form of acoustic fluctuations on parameters of an irradiated material and the law of increase in depth of a crater was estimated. It is revealed, that at action on a surface of the copper sample of a laser impulse duration 20 ms time of growth of a zone of destruction makes approximately 40 ?ñ, that will well be coordinated with time of existence of plasma formation at a surface of the target exposed to laser-plasma processing (50 ms).
waveguide resonator, misalignment of the mirrors, terahertz range, energy losses, mode composition, polarization
Vestnik KhNU ¹983 Pages. 18-22
The influence of the curvature of the spherical mirror for metallic waveguide resonator of submillimeter laser (lambda = 0.4326 mm) on energy losses and the mode composition of radiation is investigated. It is shown that the presence of quadratic phase aberrations in the mirrors of the waveguide cavity with an increase of its Fresnel number at monotonically decreasing of the energy losses for fundamental asymmetric mode TE11q due to a decrease of waveguide losses also leads to their substantial non-periodic oscillation.
nonlinear dielectric, polariton spectrum.
Vestnik KhNU ¹983 Pages. 23-28
The properties of polaritons in nonlinear dielectric medium are considered. The spectrum of polaritons is got, the dependence on intensity of electromagnetic field of number of branches and width of gaps in the spectrum is investigated. New branches arising up in the gap of polariton spectrum are found. The ratio of electromagnetic and mechanical energy of a polariton wave propagating in nonlinear dielectric is considered. It is shown, that if the frequency of polaritons go up towards the lower limit of spectral gap, the fraction of electromagnetic field energy at polariton wave goes down and tends to zero, but for the polaritons with frequency higher than upper limit of gap, the fraction of the electromagnetic field energy tends to 100 % with increasing of frequency.
5. Impact of random variations of air hole diameters and random variations of the centers position of air holes on operation parameters of a solid core microstructured optical fiber
A.I. Filipenko, A.N. Donskov
finite-element method, Gaussian distribution, inclusions diameter, total mode field power, angular positioning, microstructured optical fiber.
Vestnik KhNU ¹983 Pages. 29-32
We investigated the impact of random variations of air hole diameter and random variations of the centers position of air holes on operation parameters in the case of solid core microstructured optical fiber with a ring of air holes. The found results show that at any of considered defect types mode field will have two pronounced maximums. At practical use an investigated type of the MOF special angular positioning end faces of fibers is necessary. We also have shown that random variations of inclusions diameter can increase total mode field power. In our research we used finite-element method.
thermal nonlinearity, optical beam, total reflection, induced inhomogeneity, self-defocusing.
Vestnik KhNU ¹983 Pages. 33-37
The interaction of optical beams in media characterized by a refractive index depending on temperature is examined. The optical pump beam is partially absorbed by the medium induces a region with an inhomogeneous refractive index. As a result complete reflection, refraction or diffraction of the signal beam on the induced optical inhomogeneity may be observed. Experimental results on the research of this phenomenon are presented. Waveguide propagation of light in the region formed by two narrow pump beams is realized.
method of enveloping surfaces in medium, synchrotron-Cherenkov radiation, radiation spectrum, hopping variations.
Vestnik KhNU ¹983 Pages. 38-47
The method of enveloping surfaces is generalized for the case of the system of electrons moving along an arbitrary defined trajectory in transparent isotropic medium. The basic relationships for the classical radiation theory of the system of electrons moving in transparent isotropic medium along an arbitrary defined trajectory are obtained using this method. The hopping variations in spectral distributions of the radiation power of one, two, three, and four electrons moving along a spiral in transparent isotropic medium are studies.
8. Light propagation characteristics of optical metal dielectric coaxial nano-waveguides with complex shapes
O.N. Kozina, I.S. Nefedov, L.A. Melnikov
plasmonic waveguides, coaxial, noble metals, numerical simulations, nano-size.
Vestnik KhNU ¹983 Pages. 48-53
The properties of new optical waveguides with nanosize cross-section made of noble metals and glasses are described. This waveguide supports propagation of modes with unusual propagation properties. For estimation of the field localization, losses, propagation length, velocity and others characteristics the numerical simulations by FEM method has been used. Coaxial waveguide with the annular and the elliptic central rods are considered. The comparatively low value of losses has explained.
resonant photodiode, quantum efficiency, modulation characteristic, transfer matrix method.
Vestnik KhNU ¹983 Pages. 54-66
In this paper, we have described methods of modeling of resonant cavity photodiods based on semiconductor quantum dimensional structures for ultrashort connections. The problem of misalignment of operating wavelength of emmiter and receiver has been shown and quantum efficiency maxima spectral shift temperature dependence was analysed. Technological control of layer thickness using laser interferometer with 1 atomic layer quality control was shown. Comparative analysis made in this paper of modulation characteristic of regular and resonant cavity detectors shows more than 5 times increasing quantum efficiency and modulation band product in resonant detector case.
optical element of the cylindrical form, light scattering, Monte-Carlo method, indicatrix of scattering, index of refraction
Vestnik KhNU ¹983 Pages. 67-71
Modeling of characteristics of optical spectral-selective elements of the cylindrical form with the increased value of the refraction index, using effect of light scattering is organized. The parameters of the optical element materials, forming its spectral-selective characteristic are determined. As have shown results of researches, application of cylindrical optical element for spectral angular selection is possible in limited range of values of the index of refraction. At increase in value of refraction index before determined level the optical element starts to function in a mode of quasi uniform light scattering.
grid, bolometer, intensity distribution, polarization, energy center, beam diameter, generalized cross-sectional square of the beam.
Vestnik KhNU ¹983 Pages. 72-76
In this paper the grid receiver for measuring laser radiation characteristics has been considered. The receiver contains four grids located perpendicular to the direction of propagation. Wire elements are located at angles 0 , 45?, 90? and 135? to the vertical. One grid contains 8 nickel bolometers with diameter 40 microns, bolometers are located on 7.2 mm from each other. The diameter of the window – 60 mm. Intensity distribution in the space has been measured, therefore, the position of the energy center, the diameter, the generalized cross-sectional square of the radiation beam have been determined. The Radon transformation has been used as the mathematical basis of signal processing algorithms. Also the polarization direction and intensity distribution of polarized radiation have been measured by a numerical experiment.
wave equation, exact solutions, localized waves, Bateman solution, general astigmatism.
Vestnik KhNU ¹983 Pages. 77-83
A new class of exact non-harmonic in time solutions of 3D wave equation is established. This class is a generalization of the known complexified relatively undistorted Bateman-type solution, involving an arbitrary function, waveform. Argument of this function is much similar to that which appears in general astigmatic paraxial Gaussian beam. Special choices of the waveform allow general astigmatic beam-like and packetlike waves with Gaussian-type localization in space and time.
plasma, surface plasmons (plasmon resonances), scattering cross section, eigenvalues.
Vestnik KhNU ¹983 Pages. 84-90
Plasmon resonances of an isolated plasma cylinder and if a pair of coupled plasma cylinders are theoretically investigated. Mechanism of the plasmonic modes coupling that can be considered as symmetric and antisymmetric combinations of isolated cylinders plasmons is investigated. Accurate analysis of the spectrum of different Plasmon resonances is presented. Significant enhancement of the field in the case of distant cylinders in comparison to isolated one is revealed (separation distance is near 10-20 radii). The calculation accuracy is estimated. Figures show the scattering cross section of plane wave on the isolated plasma cylinder and on the pair of coupled cylinders and the real part of the eigenfrequency of the plasmon modes. Near field spatial characteristics of plasmons are presented.
holography, physiological optics, retina, uniaxial crystal, form-birefringence, Fresnel's formulas.
Vestnik KhNU ¹983 Pages. 91-101
Theoretical analysis of the laser radiation transmission at interface between the quasi-crystalline layers of the retina (a layer of nerve fibers and photoreceptor disks) is analyzed in a frame of holographic model of physiological optics. To solve the problem, we have obtained analogues of Fresnel's formulas for the interface between two uniaxial crystals. The results may be applied for diagnosis and treatment of ophthalmologic diseases by laser techniques.
abnormally low reflection, metamaterials, antireflection channels.
Vestnik KhNU ¹983 Pages. 102-106
The physical features analysis to describe formation the regions with extremely low reflection of electromagnetic radiation in the terahertz and far infrared ranges are presented and these regions should be observed in many experimental studies. It is shown that in case of sufficiently small damping of polar phonon the spectral bands with almost complete reflection disappearance (R <0.01%) are formed and we name these bands as antireflection channels (ARC). ARC located outside the region of negative dielectric permittivity, and the minimum reflection is shifted above the frequency of longitudinal oscillations by the value depends on the basic parameters of the polar vibrations.
gravimeter, superconducting suspension, optical registration, thin films, superconducting ring.
Vestnik KhNU ¹983 Pages. 107-113
This paper considers the problem of designing and developing optical-cryogenic devices using new physical principles, mathematical methods, and new superconducting materials. The sensor element is based on new ñontrolled magnetic levitation phenomenon, high-precision optical registration of mechanical coordinates of levitating body, and the robust signal processing tools. A controlled self-bearing probe dynamics is also analyzed. We have shown how to produce reliable YBCO thin films with controllable surfaces and physical properties and how to integrate them in a ring form into the optical-cryogenic gravimeter so as to reduce its size and render it convenient for future space applications.
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