Coherent interaction of an electromagnetic field with a medium of two-level particles and with a superconducting current in a Josephson structure

The propagation of electromagnetic pulses in Josephson structures is investigated theoretically. An analogy with interaction of light pulses with a twolevel medium is traced. Under certain conditions the propagation of electromagnetic radiation in a two-level medium and in a Josephson structure is described by the same wave equation.Lebedev Physics Institute, Academy of Sciences of the USSR, Moscwow. Translated from Preprint No. 233 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1938.     

Squeezed states of electromagnetic field

Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow. Translated from Preprint No. 232 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

Analysis of low-frequency fluctuation of the radiation power of injection lasers

Quantum Radiophysics Division, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint No. 106 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1989.     

Amplification in a semibounded free-electron laser

A self-consistent analytic expression for the complex gain of a free-electron laser is obtained on the basis of the single-particle equations with realistic boundary conditions. The results are presented in the form of amplitude-frequency and phase-frequency characteristics of a free-electron laser.New-Accelerator Problems Laboratory, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint No. 240 of the Lebedev Physics Institute, Academy of Sciences of the USSR, 1988.     

Analysis of laser-structure anisotropic semiconductors by the Bloch-function method

The method of Bloch functions is used to obtain the radiation makeup of a semiconductor laser structure consisting of periodically alternating waveguide and antiguide regions, and the differntial gains for the different modes are determined. Pumping of antiguide regions with different structure parameters makes it possible to obtain the maximum gains of a Bloch mode made up of outflowing waveguide modes at the center of the brillouin lobe. The directivity pattern contains in this case sideband satellites in addition to the central lobe. When the structure is optimized, the intensity of the central lobe amounts to 70% of the total emission intensity.Optoelectronics Laboratory, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint. No. 105 of the Lebedev Physics Institute, Academy of Sciences of the USSR, 1989.     

Coherent effects in two-level amplifying and SRS-active media

Some results are reported on coherent propagation of optical pulses. In particular, a solution is presented of the Maxwell-Bloch equations for the case of amplification of high-power pulses with varying carrier frequency but with constant number of photons in the pulse.Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow. Translated from Preprint No. 211 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

USE of negative feedback to suppress injection-laser power fluctuation

P. N. Lebedev Physics Institute. Translated from Preprint No. 215 of the Lebedev Institute of Physics, Academy of Sciences of the USSR, Moscow, 1989.     

Theoretical and numerical analysis of stresses in a laser hardening model

Kuibyshev Branch of the Lebedev Physics Institute. Translated from Preprint No. 167 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Coupling an injection laser to a single-mode optical fiberguide with the aid of a microlens in a matching-module system

Optoelectronics Laboratory, Lebedev Physics Institute. Translated from Preprint No. 192 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1989.     

Impurity micropotentials in commercial silicon crystals

The use of very cold neutrons, of laser mass spectrometry, and of secondary-ion mass spectrometry has revealed the presence of microprecipitates in commercial Si crystals grown by the Czochralski method and by float zoning.Neutron-Physics Laboratory, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint No. 149 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

Review of methods of calculating the field in optical cavities and choice of calculation method for free-flow chemical lasers

Optics Division, Lebedev Physics Institute. Translated from Preprint No. 127 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Selective laser spectroscopy of molecules in matrices. Experiments with porphyrins

A review is presented of experiments on selective laser excitation of luminescence and hole burning in the absorption spectra of porphyrins in amorphous matrices at liquid helium temperatures.Division of Quantum Radiophysics, Lebedev Physics Institute, Academy ofSciences of the USSR, Moscow. Translated from Preprint No. 165 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

Theory of spatiotemporal characteristics of laser emission. IV. Methods of controlling the spatial structures of laser beams in linear and nonlinear media

Part IV of the study continues the treatment of the theory of formation of laser beams with smooth spatial distribution, and of their conservation as they are transported in linear and nonlinear media. An exact solution is obtained for the problem of development of a small perturbation with an arbitrary amplitudephase distribution against the background of a plane wave with cubic nonlinearity. Self-consistent (waveguide) solutions of the nonlinear parabolic equation are obtained. The solutions demonstrate the effectiveness of suppression of small-scale self-focusing of diverging beams. The project of a high-aperture single-lens objective with aberration correction is developed and the relevant calculations are made.Quantum Radiophysics Division, Lebedev Physics Institute. Translated from Preprint No. 94 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Generalized coherent states of multimode light,and biphotons

Generalized coherent states of a multimode field are analyzed within the framework of the dynamic-symmetry approach and with allowance for polarization. A new class of unpolarized two-photon states is defined. The uncertainty relations and statistical and other properties of optical fields in these states are calculated and analyzed. The relations between the considered states and squeezed states of light are discussed.Optics Laboratory, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint No. 254 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow. 1988.     

Noninertial nonlinear elements and their use to control the lasing regime

Various noninertial nonlinear optical effects of electronic character that can be used as the basis of noninertial nonlinear elements capable of laser control, e.g., mode locking, separation of a single pulse, shaping a flat-top pulse, chopping a pulse, or stabilizing the emission, are condidered. The transmission of all such nonlinear filters is described in like fashion on the basis of a piecewise-linear approximation. The results are compared in a table. Various laser regimes with a similar noninertial elements inside a ring cavity are investigated theoretically.Optics Division, Lebedev Physics Institute. Translated from Preprint No. 206, Lebedev Institute of the Academy of Sciences of the USSR, Moscow, 1989.     

Fine structure of emission spectrum of a single-frequency injection laser

A theoretical analysis of single-frequency lasing is carried out in the framework of the quasimonochromatic field method with variable field amplitude and phase. The spectral optical-line profile, the spectral distribution of the laser output-power fluctuations, and the spectral distribution of the active-region density fluctuations (of the p-n voltage fluctuations) are obtained. In contrast to the known work in this field, the analysis in the present paper is carried out consistently starting with the wave equation and with account taken of the wavelike character of the radiation propagation in the active region. This has made it possible to express the final distributions in terms of quantities that are most readily measurable. Allowance for thermodynamic fluctuations has revealed an additional lasing-line broadening independent of the laser power. The analysis is not confined to lasing in the diode's own cavity, but takes into account also the possibility of using an external cavity, and corresponding varying the optical line spectral distributions, the output-power fluctuations, and p-n junction voltage fluctuations.Optoelectronics Laboratory, Lebedev Physics Institute Academy of Sciences of the USSR. Translated from Preprint No. 256 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

System for nanosecond and picosecond laser synchronization using high-voltage semiconductor switches

Results are presented on the development and investigation of a system for the synchronization of the emission of a nanosecond laser, used for plasma heating, with the emission of a diagnostic picosecond laser. The system is based on the use of the fast-semiconductor-switch technology, and ensures a temporal synchronization instability not higher than 100 psec.Laser-Plansma Laboratory and Special Design Office. Lebedev Physics Institutes, Academy of Sciences of the USSR. Translated from Preprint No. 85 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

High-power neodymium-glass waveguide laser

Results are presented of an investigation of the lasing characteristics of a high-power neodymium silicate glass spoke-waveguide laser. The influence of short-lived color centers on the lasing properties is investigated. It is shown that short-lived color centers lead to generation of regular giant pulses with repetition frequency up to 30 kHz, to a substantial lengthening of the decay time of the neodymium-ion metastable level (via a decrease of the superluminescence background) and by the same token to an increase of the lasing efficiency. A high-power technological waveguide laser with spokelike active elements, emitting a train of regular giant pulses with total emission energy up to 20 J and high homogeneity of the emission-field distribution is developed on the basis of the reported investigations.Quantum Radiophysics Division, Lebedev Physics Institute. Translated from Preprint No. 154 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Similarity of light fluxes diffracted in the far field by apertures of complicated shape

Translation of Preprint No. 189, Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Methods of estimating the angular and energy characteristics of generated laser emission

The physical models used to estimate the angular and energy characteristics of laser emission generated in the kinetic and coherent regime of emission interaction with an active medium are critically analyzed and systematized.Quantum Radiophysics and Optics Division, Lebedev Physics Institute. Translated from Preprint No. 176 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1989.