Представлены результаты разработки радиометрического комплекса для астрономических и атмосферных исследований в 3-миллиметровом диапазоне длин волн. Радиометр собран по модуляционной схеме с механическим обтюратором, реализованным на сверхразмерных квазиоптических волноводах. В качестве антенной системы использована антенна Кассегрена с диаграммой направленности 1° по уровню –3 дБ. Калибровка осуществляется по встроенному генератору шума. Для наблюдений в выделенной области небесной сферы приемная часть комплекса вместе с антенной размещена на двухкоординатном опорно-поворотном устройстве. Управление, сбор и обработка экспериментальных данных осуществляются в удаленном режиме с помощью разработанного авторами программного обеспечения.

In open publications the results of research on the third harmonic generation in the air by femtosecond laser radiation are presented. Most of the studies have been carried out using a titanium-sapphire laser with a central emission wavelength of 800 nm. This work presents for the first time the results of studies of the third harmonic generation in the air from laser radiation with a wavelength of 1032 nm. The source of the laser radiation was an ytterbium femtosecond laser which generated pulses with duration of ~ 250 fs and a repetition rate of 1 kHz. The average output power of the laser reached 1750 mW. Maximum peak intensity of excitation laser radiation was up to 10 TW/cm2. When focusing the laser radiation its filamentation took place and was accompanied by generation of the third harmonic radiation at wavelength of 344 nm. Spectral, energy and spatial characteristics of the generated third harmonic radiation were investigated. Energy measurements were carried out up to the threshold power of pump radiation at which the competing nonlinear processes in the circuit optical elements of the experimental setup began to occur. The maximum average third harmonic emission power was 1.52 mW with a third harmonic conversion efficiency of about 0.085 %. The far-field beam pattern had a symmetric Gaussian profile with a radiation divergence of 0.11 mrad which corresponds to the diffraction quality of the beam (M2 ≈ 1)

Spectra of multiparticle parametric stimulated Raman scattering in a calcite single crystal are investigated. The single crystal is excited by ultrashort pulses of the Nd3+:YAG laser with the lasing wavelengths of 532 and 1064 nm. A comb of Stokes and anti-Stokes components is observed in the visible and near infrared regions. Energy dependences are constructed for several Stokes and anti-Stokes satellites. A possibility of collinear propagation of Stokes and anti-Stokes components in forward scattering is found.

July 5 - 8, 2021, Bauman Moscow State Technical University hosted the XXII International Conference on Modern Problems of the Theory of Relativity, Cosmology, and Astrophysics “Physical Interpretations of the Relativity Theory PIRT-2021”. List of International Advisory Council, Conference Committee, Local Committee, Invited Speakers, Support to the conference are available in this pdf.

Parametric interaction of electromagnetic and gravitational waves with the radiation generation at the third harmonic wavelength is one of the ways to detect gravitational interaction in a material medium. To implement the effect in question, superstrong fields must be used, but in this case competing nonlinear processes arise, leading to the generation of the third harmonic as a result of laser radiation filamentation. This paper investigates the characteristics of the radiation recorded for femtosecond (250 fs) laser pulses with a wavelength of λ = 1032 nm focused in air. The threshold pump power made it possible to observe the formation of a filament with concomitant generation of narrow-band radiation at the focus of the lens at the third harmonic wavelength λ = 344 nm. The research presents spectral and spatial dependences of ultraviolet radiation (λ = 344 nm) at pumping power of infrared radiation (λ = 1032 nm) of 500 mW. Energy dependences of the third harmonic generation efficiency in the power range from 150 to 1750 mW are obtained.

Abstract The paper considers the problem of optical radiation propagation in a passive laser reflector satellite orbiting the Earth, along with reflected signal formation at the earth surface. In these conditions, the optical system will be significantly affected by moving media optics, which may interfere with the possibility of receiving the signal reflected by the satellite. The paper aims to develop a mathematical simulation taking into account the effects of moving media optics and track the spatiotemporal structure of the signal as a function of the optical system velocity.

We consider the possibility of generating and subsequently detecting artificial gravitational waves in a laboratory based on different approaches. As one of the methods for creating gravitational waves, we investigate oscillations of the ions of the crystal lattice of a dielectric under the influence of high-power laser radiation. The characteristics of gravitational waves obtained by this method are compared with the results of using the other approaches as well.

Abstract The mathematical model of a solid-state multi-stage laser is described. The model can be used to analyze the radiation generating process in the laser in the presence of interstage couplings, complex optimization and determining the require-ments for interstage cross-coupling nodes.

Various types of gravity wave sources were considered in this paper. It is proposed to use the effect of mutual conversion of electromagnetic and gravitational waves in a nonlinear optical dielectric medium irradiated by an intensive light source as a perspective method of generating gravitational-wave radiation.

The paper considers the problem of the laser radiation propagation from the Earth surface to a Luneburg lens moving at a speed V along a geosynchronous orbit, and the registration by a ground-based observer of radiation reflected by a lens. Preliminary calculations show that the beams reflected by the moving lens deviate at different angles, which leads to the mixing of the beams on the Earth’s surface in the region of the radiation recorded. That, in turn, affects the appearance of the interference pattern and the process of recording the radiation reflected by the lens. Therefore, the purpose of this work is to calculate the formed optical response in the reception area of the radiation, taking into account the optical effects of the moving media: the Fizeau effect, the Doppler effect, violation of the Snell’s law, the kinematic effect of the beam points displacement on the optical surface caused by the final velocity of radiation in the lens.

Abstract The paper adduces theoretical data and results of experimental studies confirming the existence of gravitational radiation predicted by the general theory of relativity. It also shows that studying of gravitational waves detection is based on equations of general relativity and equations of electrodynamics, and for modeling of gravitational waves space by sources, equations of hydrodynamics are used.

The paper proposes a mathematical model of a multistage laser based on three- and four-level active media in the plane-wave approximation. The model can be used to analyze the generation of radiation in a laser source in the presence of interstage couplings taking into account the actual quality of the optical path elements. The calculation of the pulse parameters for YAG:Nd and YSGG:Cr:Nd laser oscillators depending on the pump power is presented. The obtained results can be used to solve the problems of complex laser optimization and determine the requirements for interstage decoupling nodes.

УПРАВЛЕНИЕ ВОЛНОВЫМ ФРОНТОМ КОГЕРЕНТНОГО ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ В

The ways of generating and detecting of high frequency gravitational wave in free space and in nonlinear dielectric media under intensive electromagnetic emission excitation have been analyzed. It was shown that there is the opportunity to realize the parametric process of gravitational wave generation with high frequency ωg = 2ω0 due to combining of two electromagnetic waves with frequency ω0. In the dielectric medium synchronism conditions may be reached if the frequency ω0 of exciting light corresponds to so call unitary polaritons, characterized by unity refraction index. The detection of gravitational waves with frequency ωg = 2ω0 may be examined by means of the third harmonic generation registration in corresponding dielectric media.

In this paper we give a brief review of application of Noether symmetry and form-invariant symmetry in the analysis of the earlier stage of the universe evolution. The description of gravitational waves on the basis of the second Noether theorem is also considered.

The possibility of generating and detecting high-frequency gravitational waves based on nonlinear-optical processes in dielectric media at their excitation by intense laser radiation of visible or ultraviolet ranges is analyzed. The theory predicts the feasibility of the Hertz gravitational laboratory experiment in which the parametric conversion of intense laser radiation with frequency ω0 = 2πf0 (f0 = 1014 − 1015 Hz) to a gravitational wave with frequency ω g = 2ω0 and the reverse process of gravitational radiation reconversion to optical radiation are implemented in the condensed dielectric medium.

The study introduces a system of equations describing the propagation of light rays in laser location of a moving heterogeneous medium. A recurrent system of equations is obtained for the algorithm of modeling ray trajectories in a moving space microsatellite in the form of a two-dimensional Luneberg lens. A numerical calculation and analysis of the interference optical response of the moving Luneberg lens on the examples of BLITS and BLITS-M satellites is carried out. The results obtained indicate a complex influence of the effects of the moving media optics (Doppler and Fizeau effects, Snell's law violation, dispersion phenomenon, etc.) on the spatial and temporal characteristics of the reflected interference signal on the Earth's surface, namely on the signal-to-noise ratio in the reception area.

By analyzing the progress in the development of ideas and techniques for recording gravitational waves, the paper introduces a vector characteristic for assessing the future development of scientific knowledge (R) over right arrow (i)(t) taking into account new dynamic scientometric indicators. This characteristic is a function of time and depends on the priority assessment of the scientific problem (P) over right arrow (i)(t) of the divergence of the flow of new knowledge (Z) over right arrow (i) (t) stimulated by the solution obtained to this problem, or a new result in this area, as well as the time-varying scientometric vector potential (N) over right arrow (i)(t).

This paper presents the study of fluorescent trace in a rotating ruby crystal occurring upon irradiation of coherent emission with a wavelength lambda = 532 nm. As a sample we used an oriented cylinder-shaped ruby single crystal of 5 mm in length and 10 mm in diameter.