Частица со спином 1 в цилиндрическом базисе: метод проективных операторов

In this paper, the system of equations describing a spin 1 particle is studied in cylindric coordinates with the use of tetrad formalism and the matrix 10-dimension formalism of Duffin – Kemmer – Petieau. After separating the variables, we apply the method proposed by Fedorov – Gronskiy and based on the use of projective operators to resolve the system of 10 equations in the r variable. In the presence of an external uniform magnetic field, we construct in an explicit form three independent classes of wave functions with corresponding energy spectra. Separately the massless field with spin 1 is studied; there are found four linearly independent solutions, two of which are gauge ones, and other two do not contain gauge degrees of freedom. Meanwhile, the method of Fedorov – Gronskiy is also used.В настоящей работе система уравнений, описывающая частицу со спином 1, изучается в цилиндрических координатах с использованием тетрадного формализма и матричного 10-мерного формализма Даффина – Кеммера – Петье. После разделения переменных для решения системы 10 уравнений относительно переменной применяется метод, предложенный Федоровым – Гронским и основанный на применении проективных операторов. При наличии внешнего однородного магнитного поля построены в явном виде три независимых класса волновых функций с соответствующими энергетическими спектрами. Отдельно исследуется безмассовое поле со спином 1; найдено четыре линейно независимых решения, два из которых калибровочные, а остальные два не содержат калибровочных степеней свободы. При этом также используется метод Федорова – Гронского

Modeling and optimization of the YAG:Yb microchip laser passively Q-switched by YAG:Cr absorber

Based on analytical and numerical solutions of the rate equations system and the heat conductivity equation, the model of the quasi-three-level passively Q-switched YAG:Yb/YAG:Cr microchip laser is developed. The obtained results are used for its optimization, i.e., for the determination of the output mirror reflectivity, the pumping beam radius, the thickness of the absorber and the phototropic centers concentration maximizing the energy in the laser pulse. The influence of the thermal load on the spatial parameters of the laser beam is also determined

Optical in situ Study of Reduction/Oxidation Processes in Cr,Mg:YAG Epitaxial Film

The changes of the optical absorption spectra of Cr,Mg:YAG epitaxial film caused by high-temperature redox treatment are investigated by means of in situ spectroscopy. The spectra were registered in the visible and near-IR spectral regions at temperatures up to 1100 K. The kinetics of optical absorption changing were obtained in the temperature range from 936 K to 1091 K and were described by mathematical model connecting the chromium recharging process with oxygen vacancies diffusion. The parameters of the model were determined from the approximations of the experimental kinetics

Optimizing of the piezo-optic interaction geometry in SrB4O7 crystals

The optimal geometries of the piezo-optic interaction are determined for SrB4O7 crystals by the extreme surfaces method. The goal functions of optimization are the change of optical path length and optical path difference, normalized on mechanical stress and crystal thickness, and the parameters of optimization are the spherical angles determining the directions of the light beam propagation and the uniaxial pressure action. It is shown that the maximal changes of optical path length for the orthogonal polarized waves are equal to 2.09 or 1.65 B (1 B = 1 brewster = 10–12 m2/N) and the maximal change of optical path difference is equal to 2.22 B respectively in transversal geometry of the piezo-optic interaction (for λ =633nm and T =20ºC)

Global Maxima of the Acousto-Optic Effect in CaWO 4

The global maxima of the acousto-optic interaction are theoretically determined for CaWO₄ crystals by extreme surfaces method. As it is shown, the highest value of the acousto-optic figure of merit M₂ is equal to 14.0×10¹⁵ s³/kg and achieved in the case of the diffraction of ordinary or extraordinary light beam on the slow quasi-transversal acoustic wave. At that the incident light wave propagates close to c-axis of the crystal and the corresponding acoustic wave propagates in the direction close to the perpendicular one

Highly Nonlinear Multi-Material Chalcogenide Spiral Photonic Crystal Fiber for Supercontinuum Generation

In this paper, we have numerically simulated a highly nonlinear multi-material chalcogenide photonic crystal fiber in order to investigate both the linear and the nonlinear parameters for generating a supercontinuum. The photonic crystal fiber is designed with borosilicate and As₂S₃ glass, where borosilicate is doped in a spiral shape in the cladding region of the fiber. The designed fiber was carefully anlaysed for the parameters, effective refractive index, effective mode area, dispersion and nonlinearity coefficient. The estimated parameters are found satisfactory and suitable for further simulation and investigation of the design for broadband supercontinuum generation

Highly Nonlinear Multi-Material Chalcogenide Spiral Photonic Crystal Fiber for Supercontinuum Generation

In this paper, we have numerically simulated a highly nonlinear multi-material chalcogenide photonic crystal fiber in order to investigate both the linear and the nonlinear parameters for generating a supercontinuum. The photonic crystal fiber is designed with borosilicate and As₂S₃ glass, where borosilicate is doped in a spiral shape in the cladding region of the fiber. The designed fiber was carefully anlaysed for the parameters, effective refractive index, effective mode area, dispersion and nonlinearity coefficient. The estimated parameters are found satisfactory and suitable for further simulation and investigation of the design for broadband supercontinuum generation

Eight-Channel Optical Add Drop Multiplexer Based on Ring Resonator Using LNOI Channel Waveguides

In this paper we report on an eight-channel optical add drop multiplexer based on ring resonator using lithium niobate on insulator channel waveguides. It is suitable for a DWDM-GPON network with channel spacing of 100 GHz in C-band and data rate is 10 Gbps. The insertion loss at the drop port is maximum 1.2 dB and the Q-factor is 1636. It can be used as multiplexer as well as demultiplexer in 8-channel DWDM systems