Showing papers in "Soviet Journal of Quantum Electronics in 1980"
TL;DR: In this article, a method for calibrating photodetectors based on some characteristics of the statistics of the field of spontaneous parametric light scattering is described, and a phenomenological theory of parametric scattering is used to demonstrate that photons are only emitted in pairs.
Abstract: A description is given of a method for calibrating photodetectors based on some characteristics of the statistics of the field of spontaneous parametric light scattering. A phenomenological theory of parametric scattering is used to demonstrate that photons are only emitted in pairs. It is shown that, in principle, a priori information on the two-photon character and directionality of parametrically scattered light can be used for absolute calibration of photodetectors operated both in the analog linear regime and in the discrete photoelectron pulse counting regime.
218 citations
TL;DR: In this article, photo-induced light scattering was observed in cerium-doped (SrxBa1-x)1-1-y(Nb2O6)y crystals having the composition x = 0.61, y = 0.4993, and an analysis is made of static and dynamic characteristics of self-amplification of scattered light in the crystals.
Abstract: Photoinduced light scattering was observed in cerium-doped (SrxBa1–x)1–y(Nb2O6)y crystals having the composition x = 0.61, y = 0.4993. It was found that this effect is due to holographic amplification of light scattered by crystal defects. An analysis is made of static and dynamic characteristics of self-amplification of scattered light in the crystals. A theoretical model of the process is constructed assuming that the hologram recording process is of the diffusion type. Theoretical results are compared with the experiment.
101 citations
TL;DR: The suitability of nitrate crystals for Raman stimulated emission was demonstrated in this article, where the Stokes components of stimulated Raman scattering were compared with those of calcite.
Abstract: An investigation was made of the efficiency of stimulated Raman scattering in sodium, barium, and lead nitrates, compared with that in calcite. Measurements were made of the energies of two Stokes components of stimulated Raman scattering. The suitability of nitrate crystals for Raman stimulated emission was demonstrated.
67 citations
TL;DR: In this article, the first ever investigations of an injection laser having an unstable resonator were given, and it was found that in such a laser the transverse field distribution is stabilized and only one longitudinal mode is excited.
Abstract: A report is given of the first ever investigations of an injection laser having an unstable resonator. It was found that in such a laser the transverse field distribution is stabilized and only one longitudinal mode is excited.
53 citations
TL;DR: In this article, the optimal repetition frequency was determined not by the relaxation rate of the metastable level but by the plasma recombination rate, and it was shown that the addition of hydrogen to the Cu-Ne mixture led to an increase in the efficiency of the three-body volume recombination mechanism.
Abstract: Measurements are reported of the populations of the copper atom 2D5/2 levels and of the frequency characteristics of a copper laser utilizing self-terminating transitions, in tubes of diameter 20, 27, and 40 mm. It was shown that the optimal repetition frequency was determined not by the relaxation rate of the metastable level but by the plasma recombination rate. In a pure Cu–Ne mixture the recombination took place as a result of ambipolar diffusion, so that a lowering of the optimal repetition frequency from 1316 to 4–5 kHz was observed on increasing the diameter of the coaxial tubes from 2 to 4 cm. The addition of hydrogen to the Cu–Ne mixture led to an increase in the efficiency of the three-body volume recombination mechanism and to a substantial raising of the optimal repetition frequency.
47 citations
TL;DR: In this article, the spectral and temporal properties of the NH/sub 3/Laser were investigated and discrete tuning of the frequency was obtained over a range of 770-890 cm/sup -1/1/
Abstract: A report is given of the generation of high-power laser pulses, having an energy of 1.5 J and an efficiency of 20%, by exciting ammonia with CO/sub 2/ laser radiation. The spectral and temporal characteristics of the NH/sub 3/ laser were investigated. Discrete tuning of the frequency was obtained over a range 770--890 cm/sup -1/. A study was made of the mechanism by which the ammonia absorbed the pump radiation and a procedure was found for increasng the NH/sub 3/ laser efficiency.
46 citations
TL;DR: In this article, the populations of the first excited states of neon-like ions were calculated using a radiative collisional model which allows for all the levels of the 1s22s22p53s, 2p53p, and 2p 53d configurations.
Abstract: A radiative collisional model which allows for all the levels of the 1s22s22p53s, 2p53p, and 2p53d configurations is used to calculate the populations of the first excited states of neon-like ions. An earlier conclusion that an inversion exists between levels of the lp 2p53p and 2p53s configurations in a stationary plasma is confirmed. It is shown that an inversion with a fairly high gain is due to not one but several types of transitions covering a wide wavelengths range.
37 citations
TL;DR: In this article, a review of experimental data on exciplex lasers is given, including optical characteristics of lasing transitions, experimental conditions for achieving laser action, mechanisms of formation of active level populations, character of nonequilibrium of the active medium, and proposed new active media.
Abstract: A review is given of experimental data on exciplex lasers. An analysis is made of the optical characteristics of lasing transitions, experimental conditions for achieving laser action, mechanisms of formation of the active level populations, character of nonequilibrium of the active medium, and proposed new active media. Detailed tables are presented with data on optical transitions, exciplex quenching rates, and characteristic parameters of the media and pump sources of existing lasers.
36 citations
TL;DR: In this article, the dispersion of the refractive index n (λ) of glassy GeO2 in the spectral range 0.5-2.5 μ was investigated and it was found that this dispersion vanished near λ 0 = 1.74 μ.
Abstract: An investigation was made of the dispersion of the refractive index n (λ) of glassy GeO2 in the spectral range 0.5–2.5 μ. It was found that this dispersion of GeO2 vanished near λ0 = 1.74 μ. The Brillouin scattering method was used to determine the elastic and photoelastic constants of GeO2 and to find the Rayleigh scattering coefficient, which indicated that the upper limit for the Rayleigh scattering losses was 0.30 dBAm at the wavelength of μ = 1.74 μ. The possibility of using GeO2 fibers is considered and their advantages over SiO2 fibers in the wavelength range 1.7–1.8 μ are stressed.
35 citations
TL;DR: In this paper, an investigation was made of the lasing properties of Q-switched YAG:Er/sup 3 +/ crystals (/sup 4/I/sub 11/2/--/sup 4 /I//sub 13 /2/), and an energy of 100 mJ was obtained in the TEM/sub 00/ mode and the pulse duration was 65 nsec.
Abstract: An investigation was made of the lasing properties of Q-switched YAG:Er/sup 3 +/ crystals (/sup 4/I/sub 11/2/--/sup 4/I/sub 13/2/). An energy of 100 mJ was obtained in the TEM/sub 00/ mode and the pulse duration was 65 nsec. Under free-lasing conditions, the efficiency was 1.25% and the output radiation energy 5 J. The radiation parameters were strongly influenced by the Stark splitting of the /sup 4/I/sub 11/2/ and /sup 4/I/sub 13/2/ active levels.
33 citations
TL;DR: In this article, it was shown that the losses per pass through an active element placed between two crossed polarizers can be halved by the use of elements cut along the fourfold axis of a YAG : Nd3+ crystal.
Abstract: A calculation is reported of the depolarization of linearly polarized light by a YAG : Nd3+ cylindrical active element kept under uniform heat evolution and heat removal conditions. It is shown that the losses per pass through an active element placed between two crossed polarizers can be approximately halved by the use of elements cut along the fourfold axis of a YAG : Nd3+ crystal.
TL;DR: In this paper, the structure of the oscillation modes and normal frequencies of a resonator with a wavefront-reversing mirror was studied and it was shown that when this resonator is filled with a linear and reciprocal medium, the fundamental oscillation mode has lower losses than the fundamental modes of any filled resonators formed by conventional mirrors of the same size.
Abstract: The paraxial approximation is used to study the structure of the oscillation modes and normal frequencies of a resonator with a wavefront-reversing mirror. It is shown that when this resonator is filled with a linear and reciprocal medium, the fundamental oscillation mode has lower losses than the fundamental oscillation modes of any filled resonators formed by conventional mirrors of the same size. The absence of discrete normal frequencies in the resonator is noted.
TL;DR: In this article, the authors investigated the mechanism of spontaneous antiphase fluctuations of the intensity of the opposite waves in a solid-state ring laser and found that backscattering-induced coupling of the waves is only responsible for fluctuations at a frequency higher than that of the relaxation oscillations.
Abstract: An investigation is made of the mechanism of spontaneous antiphase fluctuations of the intensity of the opposite waves in a solid-state ring laser. It is found that backscattering-induced coupling of the waves is only responsible for fluctuations at a frequency higher than that of the relaxation oscillations. A hypothesis is put forward that the lower-frequency fluctuations may be due to instability of the laser parameters. Computer calculations using a laser model with low-frequency antiphase modulation of the opposite wave losses confirm that this interpretation is feasible.
TL;DR: In this paper, the spectral composition of the spontaneous radiation, superradiance, and laser radiation emitted by a pulsed copper vapor laser was investigated, and it was found that the observed spectral structure of the laser radiation and super-radiance was governed by the hyperfine and isotopic splitting of the active levels of the copper atom.
Abstract: An investigation was made of the spectral composition of the spontaneous radiation, superradiance, and laser radiation emitted by a pulsed copper vapor laser. The time resolution was about 3 nsec. It was found that the observed spectral structure of the laser radiation and superradiance was governed by the hyperfine and isotopic splitting of the active levels of the copper atom. In the absence of saturation of the active medium a narrowing of the spectral line profiles was observed during a superradiance pulse. When saturation was achieved for superradiance and lasing, the line profiles broadened to the width of the spontaneous emission line during a radiation pulse. It was found that the temperature of the gas in the copper vapor laser did not exceed 2500°K.
TL;DR: In this article, a matrix method is developed for the calculation of the evolution of small-scale self-focusing as applied to laser amplifier systems, i.e., active elements with a nonlinear refractive index, separated by air gaps or lens systems.
Abstract: A matrix method is developed for the calculation of the evolution of small-scale self-focusing as applied to laser amplifier systems, i.e., active elements with a nonlinear refractive index, separated by air gaps or lens systems. Calculations made for collimated and diverging laser beams indicate that in amplifier systems it is preferable to use spatial filters with beam expansion. These calculations can be used to optimize their parameters.
TL;DR: In this article, a phase shifting mask is used to increase the discrimination between the modes compared with the familiar absorbing mask method or to reduce the losses of the selected mode with the same degree of discrimination.
Abstract: A description is given of a method of selecting pure transverse laser modes by a phase-shifting mask positioned along nodal lines of the selected mode on one of the optical resonator mirrors. This makes it possible to increase the discrimination between the modes compared with the familiar "absorbing" mask method or to reduce the losses of the selected mode with the same degree of discrimination. Results of numerical calculations and an experiment at λ = 0.63μ are reported and these confirm the above conclusion.
TL;DR: In this paper, a study of the kinetics of the emission spectra of wide-band dye lasers in the presence of weak frequency-dependent resonator losses was made, and it was found that the position of the center of the spectrum fluctuated because of instability of the pump power.
Abstract: A study was made of the kinetics of the emission spectra of cw wide-band dye lasers in the presence of weak frequency-dependent resonator losses. It was found that the position of the center of the emission spectrum fluctuated because of instability of the pump power. Optimization of the pump parameters ensured stable emission of a given frequency for periods up to 10 msec, which corresponded to a sensitivity of 10−9 cm−1 in intracavity laser spectroscopy.
TL;DR: In this paper, an investigation was made into second harmonic generation, in an ADP crystal, of pulsed copper vapor laser radiation and the dependence of the conversion efficiency on the average excitation radiation power was found.
Abstract: An investigation was made into second harmonic generation, in an ADP crystal, of pulsed copper vapor laser radiation. The dependence was found of the conversion efficiency on the average excitation radiation power. The maximum conversion efficiency was 8.5%. Thermal self-interaction effects were found to be the principal factor limiting the attainment of high average powers at the second harmonic frequency.
TL;DR: In this paper, the authors studied the spectra of stimulated emission from Y3AI5O12:Er3+ crystals (4I11/2-4I13/2) containing 20 wt.% activator ions.
Abstract: Studies of the spectra of stimulated emission from Y3AI5O12:Er3+ crystals (4I11/2–4I13/2) containing 20 wt.% activator ions, showed that, as the temperature decreased from 300 to 77°K, a change was observed in the emission wavelength (at T = 300°K it was found that λ1 = 2.9364 μλ2 = 2.8310μ and at T = 77°K it was found that λ1 = 2.6930 μ, λ2 = 2.8970 μ). This could not be attributed to a thermal redistribution of the populations of the Stark components of the 4I11/2 and 4I13/2 upper and lower active levels. An analysis of the results showed that the temperature shift of the stimulated emission spectrum was due to changes in the processes of relaxation of excitation from the upper levels of the Er3+ ion which caused substantial changes in the populations of the 4I11/2 and 4I13/2 multiplets.
TL;DR: In this article, a homogeneous single crystal of mercury thiogallate HgGa2S4 was grown and its diameter and length were 12 mm and 40 mm, respectively; the absorption coefficient was of the order of 0.1 cm−1.
Abstract: Homogeneous single crystals of mercury thiogallate HgGa2S4 were grown. Their diameter and length were 12 mm and 40 mm, respectively; the absorption coefficient was of the order of 0.1 cm−1. The nonlinear susceptibility coefficients d36(HgGa2S4) = 1.8d36(AgGaS2) and d31(HgGa2S4) = 0.6d36(AgGaS2) were determined.
TL;DR: In this paper, the growth conditions for the AgGa1-xInxS2 system and single crystals with the compositions x = 0.08, 0.2 and 0.6 were grown.
Abstract: A study was made of the growth conditions for the AgGa1–xInxS2 system and single crystals with the compositions x = 0.08, 0.2 and 0.6 were grown. The absorption coefficients and the refractive indices were measured in the range 0.55–11.5 μ. The wavelength dependences of the refractive indices were approximated by the Sellmeier polynomials. The phase matching diagrams were plotted for the oo-e frequency mixing process. A study was made of the influence of the percentage amounts of gallium and indium in these single crystals on the phase-matching conditions.
TL;DR: In this article, an investigation was made of optical systems performing wavefront reversal of the radiation in a stimulated Brillouin scattering (STBS) mirror and used to generate short (~10−9 sec) high-power pulses in neodymium-glass amplifiers.
Abstract: An investigation was made of optical systems performing wavefront reversal of the radiation in a stimulated Brillouin scattering (STBS) mirror and used to generate short (~10−9 sec) high-power pulses in neodymium-glass amplifiers. For a single-channel system the most suitable arrangement in practice was one in which reflection with wavefront reversal by an STBS mirror took place under steady-state STBS conditions, while a short pulse of the required duration was chopped out of the reflected radiation by a special switch. A method was found for eliminating depolarization of the radiation and inhomogeneities in the transverse distribution of the gain in the neodymium rods and this made it possible to achieve wavefront reversal of the radiation in a high-power laser system with a diffraction-limited accuracy (E≈50J, τ≈2 nsec, θ≈2×10−5 rad).
TL;DR: In this article, a rigorous asymptotic and numerical analysis is made of the spatial coherence function of the field of a laser beam propagating in a turbulent atmosphere, and the maximum excess of the coherence radius of a spatially bounded beam over the values of this radius for plane and spherical waves is determined under conditions of strong intensity fluctuations.
Abstract: A rigorous asymptotic and numerical analysis is made of the spatial coherence function of the field of a laser beam propagating in a turbulent atmosphere. The form of the spatial coherence function is established and the maximum excess of the coherence radius of the field of a spatially bounded beam over the values of this radius for plane and spherical waves is determined under conditions of strong intensity fluctuations. The accuracy of approximations obtained earlier for the coherence radius of the field of a laser beam is estimated.
TL;DR: In this article, a theoretical analysis of the polarization properties of wavefront reversal under four-wave interaction conditions is made and a system for complete spatial polarization wave front reversal is proposed and implemented experimentally.
Abstract: A theoretical analysis is made of the polarization properties of wavefront reversal under four-wave interaction conditions. A system for complete spatial-polarization wavefront reversal is proposed and implemented experimentally. This utilized propagation of the signal being reversed in the direction of the polarization unit vector of the reference waves.
TL;DR: In this article, a comparative study of the characteristics of copper and copper halide vapor laser, excited by regular pulses, was carried out and an average output power of 13 W was obtained and an efficiency of 1% were obtained for all these lasers.
Abstract: The results are given of a comparative study of the characteristics of copper and copper halide vapor lasers, excited by regular pulses. It was found that the lasing characteristics of copper chloride and copper bromide vapor lasers were practically identical, both under excitation conditions which correspond to the optimal efficiency and under other excitation conditions, and that they differed from those of a copper vapor laser. An average output power of ~13 W was obtained and an efficiency of 1% were obtained for all these lasers. The indications are that the advantage of employing a particular type of laser will be mainly determined in practice by the convenience of using the given design to solve a specific problem.
TL;DR: In this article, a theoretical analysis of small-scale distortions of the scattered wave formed during wavefront reversal in stimulated Brillouin backscattering of a pump beam consisting of a strong plane wave and interfering components with an extended angular spectrum is made.
Abstract: A theoretical analysis is made of small-scale distortions of the scattered wave formed during wavefront reversal in stimulated Brillouin backscattering of a pump beam consisting of a strong plane wave and interfering components with an extended angular spectrum. The relative value of the distortions is mainly determined by the small parameter g/kθ2 (g is the gain in reciprocal centimeters, k is the wave number, and θ is the angular divergence). An investigation is made of the conditions when the addition of a plane wave to the wave with an extended angular spectrum improves and causes a deterioration in the quality of the small-scale wavefront reversal.
TL;DR: In this article, an experimental investigation was made of the dynamics of plasma formation close to the surface of a graphite target in air and inert gases in the range of pressures 0.1-760 Torr and of laser radiation flux densities (0.1−1.4)×108 W/cm2.
Abstract: An experimental investigation was made of the dynamics of plasma formation close to the surface of a graphite target in air and inert gases in the range of pressures 0.1–760 Torr and of laser radiation flux densities (0.1–1.4)×108 W/cm2. It was found that a plasma appeared 40–130 nsec after the start of the laser pulse due to evaporation of the target and subsequent ionization of its vapor by the laser radiation.
TL;DR: In this article, a solution to the problem of finding the fields in a resonator formed by two wavefront-reversing mirrors was given, and it was shown that the resonator fields take the form of a Gaussian-Hermitian beam whose axis is generally inclined to the resonance axis.
Abstract: A solution is given to the problem of finding the fields in a resonator formed by two wavefront-reversing mirrors. It is shown that the resonator fields take the form of a Gaussian-Hermitian beam whose axis is generally inclined to the resonator axis.
TL;DR: A review of theoretical and experimental investigations of the optical rectification effect (ORE) in nonlinear crystals is given in this article, focusing on aspects of using this effect for measurements of the nonlinear susceptibilities of crystals, measurement of the power, polarization, and profile of laser pulses, excitation of electromagnetic waves in waveguides and resonators, generation of infrared radiation, and nonlinear spectroscopy.
Abstract: A review is given of theoretical and experimental investigations of the optical rectification effect (ORE) in nonlinear crystals. Attention is focused on aspects of using this effect for measurements of the nonlinear susceptibilities of crystals, measurements of the power, polarization, and profile of laser pulses, excitation of electromagnetic waves in waveguides and resonators, generation of infrared radiation, and nonlinear spectroscopy. Further potential uses of the ORE are discussed.
TL;DR: In this paper, the photogalvanic effect in electrooptic crystals (also known as the bulk photovoltaic effect) provides an efficient mechanism for holographic recording and interaction of light waves which results in unidirectional energy exchange.
Abstract: It is shown theoretically that the photogalvanic effect in electrooptic crystals (also known as the bulk photovoltaic effect) provides an efficient mechanism for holographic recording and interaction of light waves which results in unidirectional energy exchange. This mechanism has different properties to the previously known drift and diffusion mechanisms, and may be used directly for optical measurements of the components of the photogalvanic tensor.