Showing papers in "Soviet Journal of Quantum Electronics in 1983"
TL;DR: In this article, the future trends in the development and design of high-power pulsed solid-state laser systems are considered in relation to the laser fusion problem, and the possibility of using other media, particularly ion-doped crystals, is also discussed.
Abstract: The future trends in the development and design of high-power pulsed solid-state laser systems are considered in relation to the laser fusion problem. Attention is concentrated on neodymium-doped glass lasers, but the possibility of using other media, particularly ion-doped crystals, is also discussed. New methods for pumping such systems (both existing and future) are reviewed. Ways and means of tuning the emission wavelengths, methods for increasing the average power, and characteristic features of the design of systems as a whole are also discussed.
65 citations
TL;DR: In this paper, the authors demonstrated that steady-state emission was possible from an YAG:Er3+ laser utilizing the self-terminating 4I11/2-4I13/2 transition with a cross-relaxing lower level.
Abstract: Experimental and theoretical studies demonstrated that steady-state emission was possible from an YAG:Er3+ laser utilizing the self-terminating 4I11/2–4I13/2 transition with a cross-relaxing lower level (4I13/2)
62 citations
TL;DR: In this paper, an analysis was made of a new configuration of a laser utilizing the 4I11/2/2-4I 11/2 transition in the Er3+ ions in YAG with a high activator concentration (~5×1021cm−3).
Abstract: An analysis was made of a new configuration of a laser utilizing the 4I11/2–4I11/2 transition in the Er3+ ions in YAG with a high activator concentration (~5×1021cm−3). It is shown that at a certain excitation rate the cross-relaxation processes increase considerably the lasing efficiency and make it possible to achieve cw emission as a result of transitions from a long-lived lower level.
52 citations
TL;DR: In this article, the spectral, luminescence, and lasing properties of gadolinium scandium gallium garnet (GSGG) crystals activated with neodymium and chromium ions were investigated.
Abstract: An investigation was made of the spectral, luminescence, and lasing properties of gadolinium scandium gallium garnet (GSGG) crystals activated with neodymium and chromium ions in which the efficiency of transfer of excitation from chromium to neodymium ions is considerably higher than in YAG:Nd3+:Cr3+. It was found that the parameter characterizing the probability of an elementary Cr3+–Nd3+ interaction event for GSGG was twenty times higher than that for YAG and twice that for gadolinium gallium garnet. Investigations were made of the free lasing parameters of GSGG:Nd3+:Cr3+ and it was found that the maximum differential lasing efficiency was twice that of GSGG:Nd3+. It is concluded that efficient Cr3+→Nd3+ energy transfer can improve severalfold the energy characteristics of cw and pulsed neodymium lasers.
47 citations
TL;DR: In this article, a wide-band electronic circuit for automatic phase control (based on an external high-Q interferometer) on the emission spectrum of an injection laser was proposed.
Abstract: Theoretical estimates of narrowing of the emission line of an injection laser with an external resonator are obtained for different mechanisms that determine the line width. If the width of a line emitted by a laser diode without an external feedback ("initial" width) is governed by phase fluctuations because of the spontaneous noise, then the width of a line emitted by an injection laser with an external resonator is a quadratic function of the line width of the resonator itself. However, if the initial width is determined by fluctuations of the refractive index of the active medium, then the same dependence is linear. It is shown that external resonator configurations used so far have not been optimal. Ways are suggested for introducing high-Q interferometers into the external part of a composite resonator of an injection laser, which should make it possible to reduce the width of the emission line of a laser with an external resonator to ~1–103 Hz without altering the dimensions. An analysis is made of the influence of a wide-band electronic circuit for automatic phase control (based on an external high-Q interferometer) on the emission spectrum of an injection laser. It is shown that the "natural" width of an emission line may be reduced by between four and six orders of magnitude if the proposed method is used.
37 citations
TL;DR: In this article, a new lasing transition in the Tm3+ ion, 3H4→3F4 (corresponding to emission at the wavelength of 1482 μ in BaYb2F8:Tm3 + and at 14625 μ in LiYbF4:T m3+), which was pumped in several stages by neodymium laser radiation was investigated.
Abstract: An investigation was made of a new lasing transition in the Tm3+ ion, 3H4→3F4 (corresponding to emission at the wavelength of 1482 μ in BaYb2F8:Tm3+ and at 14625 μ in LiYbF4:Tm3+), which was pumped in several stages by neodymium laser radiation
34 citations
TL;DR: In this article, the feasibility of effective time compression of light pulses as a result of stimulated Brillouin scattering of a light beam in gases was investigated and an optimal focusing geometry and a specific excess above the scattering threshold made it possible to achieve time compression by a factor of 20-30 and the duration of the Stokes pulse was then an order of magnitude less than the decay time of hypersound.
Abstract: Theoretical and experimental investigations were made of the feasibility of effective time compression of light pulses as a result of stimulated Brillouin scattering of a light beam in gases. An optimal focusing geometry and a specific excess above the scattering threshold made it possible to achieve time compression by a factor of 20–30 and the duration of the Stokes pulse was then an order of magnitude less than the decay time of hypersound. Stimulated Brillouin scattering in argon at various pressures, corresponding to relaxation times in the range from 1 to 8 nsec, was used to convert pump pulses of 20 nsec duration into Stokes pulses of 1 nsec duration. The energy efficiency of the process was in excess of 80% and the angular divergence was not affected.
33 citations
TL;DR: Theoretical and experimental investigations of the interaction of spectral modes in an injection laser, including the case of an external dispersive resonator, have been carried out in this article, where a theory is proposed of a nonlinear interaction between modes which does not disappear on reduction in the intraband relaxation time and it is shown that this interaction suppresses amplification at relatively small separations from the frequency of a strong mode.
Abstract: Theoretical and experimental investigations are reported of the interaction of spectral modes in an injection laser, including the case of an external dispersive resonator. A theory is proposed of a nonlinear interaction between modes which does not disappear on reduction in the intraband relaxation time and it is shown that this interaction suppresses amplification at relatively small separations (~1/τ, where τ is the carrier lifetime) from the frequency of a strong mode. Experimental observations are reported of selective self-stabilization of single-frequency emission within a band of width 1/τ. This stabilization effect facilitates generation of highly coherent radiation in injection lasers.
30 citations
TL;DR: In this paper, the efficiency of hydrodynamic energy transfer in the corona of a laser plasma allowing for energy transfer by fast electrons was investigated and an analytic solution of the rate equation for fast electrons is used to determine the nature of energy release from fast electrons.
Abstract: An investigation is made of the efficiency of hydrodynamic energy transfer in the corona of a laser plasma allowing for energy transfer by fast electrons. An analytic solution of the rate equation for fast electrons is used to determine the nature of energy release from fast electrons. The corona parameters for spherical laser targets and the coefficient of hydrodynamic energy transfer are determined by an analytic solution of steadystate hydrodynamic equations. It is found that energy transfer by fast electrons increases the hydrodynamic efficiency of long-wavelength CO2 lasers.
26 citations
TL;DR: In this paper, it was demonstrated experimentally and theoretically that a cw dye laser with a ring cavity resonator and a passive mode locking can emit pulses of variable duration ranging from 1 psec down to 55 fsec and wavelengths from 615 to 624 nm.
Abstract: It is demonstrated experimentally and theoretically that a cw dye laser with a ring cavity resonator and a passive mode locking can emit pulses of variable duration ranging from 1 psec down to 55 fsec and wavelengths from 615 to 624 nm. The tuning of the pulse duration is achieved by varying the optical path in an intracavity glass prism. Phase modulation because of saturation of a nonlinear absorber compresses the pulses in the dispersive material of the prism. A theoretical model of mode self-locking between colliding pulses is proposed.
25 citations
TL;DR: In this article, a comprehensive study of the processes of laser damage to a wide class of transparent polymers, which have made it possible to determine the laser damage mechanism, is reported, which is dominated by the molecular characteristics of modifying additives present in polymers.
Abstract: An analysis is made of the possibility of using transparent polymer materials to fabricate various optical components of lasers, including active elements containing lasing dyes, bleachable filters for Q-switching, etc. A comprehensive study is reported of the processes of laser damage to a wide class of transparent polymers, which have made it possible to determine the laser damage mechanism. The mechanism of nucleation of microdamage initiated by absorbing defects is dominated by the molecular characteristics of modifying additives present in polymers. The growth of microdamage to macroscopic dimensions is influenced greatly by the viscoelastic properties of the polymer matrix. These ideas about the mechanism of laser damage of transparent polymer materials are used in suggesting ways of increasing their optical (laser) strength, which—when implemented—can ensure that the optical strength of polymers becomes comparable with that of crystals or glasses.
TL;DR: In this article, the possibility of using a laser plasma as an active medium in vacuum ultraviolet lasers was investigated, and the optimal conditions for lasing in a medium consisting of Ne-like ions were found.
Abstract: An investigation is made of the possibility of using a laser plasma as an active medium in vacuum ultraviolet lasers. A theoretical model allows for the absorption of external radiation, heat transfer, cylindrical expansion of matter, electron–ion relaxation, and for detailed kinetics of the excitation, ionization, and recombination of ions. The optimal conditions for lasing in a medium consisting of Ne-like ions are found.
TL;DR: In this paper, physicochemical, spectroscopic, and lasing properties of lanthanum neodymium magnesium hexaaluminate single crystals were investigated, and it was found that concentration quenching of the luminescence was fairly weak in these crystals.
Abstract: An investigation was made of the physicochemical, spectroscopic, and lasing properties of lanthanum neodymium magnesium hexaaluminate single crystals It was found that concentration quenching of the neodymium luminescence was fairly weak in these crystals Lasing in these crystals was studied in the 106 μ range at 300 K Prospects for using hexaaluminate in laser technology are discussed
TL;DR: In this article, a numerical investigation of the simultaneous influence of the Kerr nonlinearity and the third-order dispersion on the envelope of picosecond pulses propagating in a single-mode optical fiber is presented.
Abstract: A numerical investigation is reported of the simultaneous influence of the Kerr nonlinearity and of the thirdorder dispersion on the envelope of picosecond pulses propagating in a single-mode optical fiber. It is shown that in the region of zero second-order dispersion (k''ω2=0, λ≈1.3 μ) the nonlinearity results in splitting of an input pulse into subpulses, causes its overall broadening, and induces an additional delay of the energy center of a wave packet compared with the linear case.
TL;DR: In this paper, a laser continuously tunable in the range 766-820 nm was constructed, which utilizes an electronic-vibrational transition in chromium in a gadolinium scandium gallium garnet crystal.
Abstract: A laser continuously tunable in the range 766–820 nm was constructed. It utilizes an electronic–vibrational transition in chromium in a gadolinium scandium gallium garnet crystal kept at room temperature and subjected to nonselective flashlamp pumping.
TL;DR: In this article, a theoretical analysis of the tuning charactenstics and spectrum of an optical parametric oscillator with a quadratically nonlinear medium is presented, and the observed anomalies can be used to generate wideband picosecond radiation (continuum) in the infrared range.
Abstract: A theoretical investigation is made of the tuning charactenstics and of the spectrum of an optical parametric oscillator with a quadratically nonlinear medium. Anomalous behavior of these characteristics is reported for a number of nonlinear crystals and it is attributed to the dispersion properties of these crystals. The observed anomalies can be used to generate wide-band picosecond radiation (continuum) in the infrared range, and also to form light pulses of duration amounting to a few femtoseconds.
TL;DR: In this article, a review of the development and applications of spatial light modulators (controlled transparencies) in the form of photosensitive multilayer structures containing a liquid crystal is given.
Abstract: A review is given of recent progress in the development and applications of spatial light modulators (controlled transparencies) in the form of photosensitive multilayer structures containing a liquid crystal. A considerable improvement is reported in the most important parameters of the process of modulation of light such as the sensitivity (now 10−11 J/cm2), resolution (now 300 mm−1), and speed of response (hundreds and thousands of frames per second). There has been an expansion in the functional capabilities: the modulators can now handle infrared radiation, identify boundaries of objects and regions with time-dependent illumination in converted images, modulate light at one or several stable transmission levels, etc. Some new applications are described, particularly those in processing of television images and in real-time interferometry.
TL;DR: The scalar form of the Green function is used in a theoretical estimate of the change in the polarization of light arriving from objects located at large distances from the Earth and atmosphere, when strong fluctuations of the phase occur as discussed by the authors.
Abstract: The scalar form of the Green function is used in a theoretical estimate of the change in the polarization of light arriving from objects located at large distances from the Earth and atmosphere, when strong fluctuations of the phase occur. Computer calculations indicate that under these conditions the polarization of light is one of the most stable characteristics that are not distorted in the atmosphere.
TL;DR: In this article, a method for the analysis of the transverse mode composition of multimode coherent optical fields, proposed earlier by some of the present authors, was used to study a synthesized standard multimode beam.
Abstract: A method for the analysis of the transverse mode composition of multimode coherent optical fields, proposed earlier by some of the present authors, was used to study a synthesized standard multimode beam. Synthesized filters made it possible to reduce the error of such analysis to less than 1%.
TL;DR: In this paper, an investigation was made of the time structure of giant laser pulses emitted by a neodymium glass-fiber laser and partial mode locking occurred within some mode groups.
Abstract: An investigation was made of the time structure of giant laser pulses emitted by a neodymium glass-fiber laser. Partial mode locking occurred within some mode groups. An explanation of this effect is provided.
TL;DR: In this article, an experimental investigation was made of a detector of submillimeter radiation utilizing a difference frequency generated as a result of stimulated scattering by polaritons in a crystal of lithium niobate.
Abstract: An experimental investigation was made of a detector of submillimeter radiation utilizing a difference frequency generated as a result of stimulated scattering by polaritons in a crystal of lithium niobate. When the pump pulse duration was 2τp = 18 nsec and the cross-sectional area of the pump beam was Qp = 0.17 cm2, about 4×105 photons with frequencies in the range 25–35cm−1 were detected in a solid angle Ω = 10 msr for the signal/noise ratio of 5. The experimental results were in qualitative agreement with theoretical estimates obtained allowing for the finite apertures of the interacting waves.
TL;DR: In this article, a new proposal is made and discussed that it should be possible to operate a chemical oxygen-iodine laser not with the aid of a cooled trap for freezing out water vapor and hydrogen peroxide, but by deep cooling of a chemical generator.
Abstract: A new proposal is made and discussed that it should be possible to operate a chemical oxygen–iodine laser not with the aid of a cooled trap for freezing out water vapor and hydrogen peroxide, but by deep cooling of a chemical generator. This may improve considerably the operating characteristics of such a laser.
TL;DR: In this article, a theoretical analysis is made of some features of stimulated light scattering which may occur as a result of the dependence of the rate of heat release on the radiation intensity in the active medium of a CO2 laser.
Abstract: A theoretical analysis is made of some features of stimulated light scattering which may occur as a result of the dependence of the rate of heat release on the radiation intensity in the active medium of a CO2 laser. The main energy and spectral characteristics of this process are found. It is shown that the parameters of the scattered radiation depend strongly on the time lag of the heat release which is governed by the relationship between the modulation period of the radiation intensity and the characteristic time of the radiation-induced heating of the medium.
TL;DR: In this paper, a singlet oxygen generator was proposed, in which an alkali solution of hydrogen peroxide is atomized in a stream of gaseous chlorine, and a model was developed and used to study the influence of the parameters of a gas-liquid mixture on the characteristics of the generator.
Abstract: A proposal is made for a singlet oxygen generator in which an alkali solution of hydrogen peroxide is atomized in a stream of gaseous chlorine. A model is developed and used to study the influence of the parameters of a gas-liquid mixture on the characteristics of the generator. It is shown that the oxygen pressure at the exit from the generator can be up to 6 kPa and the relative concentration of O2(1Δ) may exceed 50%. The possibility of technical implementation of the proposed generator is discussed.
TL;DR: Theoretical and experimental studies were made of the characteristics of formation of the spatial structure of a high-power light beam emitted by a neodymium glass laser system as discussed by the authors.
Abstract: Theoretical and experimental studies were made of the characteristics of formation of the spatial structure of a high-power light beam emitted by a neodymium glass laser system.
TL;DR: In this article, a theoretical analysis of the amplification of picosecond infrared radiation pulses in a CO2 amplifier where the gas pressure varies from 1 to 10 atm was performed. And the authors showed that strong broadening of a pulse accompanies amplification during the inital stage of the process.
Abstract: A theoretical investigation is reported of the amplification of picosecond infrared radiation pulses in a CO2 amplifier where the gas pressure varies from 1 to 10 atm. The discrete structure of the vibrational–rotational spectrum of the CO2 molecule gives rise to a number of special physical features of the amplification process. In the linear amplification regime a fairly short input pulse creates a train of pulses which follow one another and the period is governed by the discrete nature of the spectrum of the amplifying medium. In the nonlinear regime only the first pulse of a train is amplified effectively. A train of this kind does not appear when the duration of an input pulse is greater than the reciprocal of the frequency width of the spectrum of the medium. Instead, strong broadening of a pulse accompanies amplification during the inital stage of the process and this may be used to generate synchronized picosecond and nanosecond pulses.
TL;DR: In this article, the process of excitation of HgCl, HgBr, and HgI/sub 2/ molecules by electron impact was investigated, and the role of such dissociative excitation in lasing was analyzed.
Abstract: An investigation was made of the process of excitation of HgCl/sub 2/, HgBr/sub 2/, and HgI/sub 2/ molecules by electron impact producing B/sup 2/..sigma../sup +//sub 1/2/ states of HgCl*, HgBr*, and HgI*. The maximum values of the cross sections for dissociative excitation were found at low electron energies; the values of these cross sections were sigma = (6 +- 3) x 10/sup -18/, (7.5 +- 3) x 10/sup -17/, and (1.2 +- 0.6) x 10/sup -17/ cm/sup 2/ for HgCl*, HgBr*, and HgI*, respectively. The role of such dissociative excitation in lasing was analyzed.
TL;DR: In this paper, the spectroscopic and lasing properties of lanthanum neodymium magnesium hexa-aluminate crystals were investigated and continuous lasing was obtained for the first time in these crystals in the 106 μ range at room temperature.
Abstract: Investigations were made of the spectroscopic and lasing properties of lanthanum neodymium magnesium hexa-aluminate crystals Continuous lasing was obtained for the first time in these crystals in the 106 μ range at room temperature
TL;DR: In this paper, it was shown that interference between the incident radiation and the resultant surface electromagnetic waves may give rise to spatially inhomogeneous heating of the surface of a medium.
Abstract: It is shown that interference between the incident radiation and the resultant surface electromagnetic waves may give rise to spatially inhomogeneous heating of the surface of a medium. The subsequent spatially inhomogeneous evaporation of matter from the surface increases exponentially (on the time scale) the amplitudes of surface gratings. The periods and growth increments of such gratings are calculated as a function of the frequency, polarization, angle of incidence, and intensity of the radiation incident on a surface.
TL;DR: In this article, the authors made an analysis of the laws governing the cumulative effect of laser damage to optical materials in the multiple-exposure regime and proposed a method for studying this effect based on a statistical approach.
Abstract: An analysis is made of the laws governing the cumulative effect in laser damage to optical materials. A method for studying this effect, based on a statistical approach, is proposed and the main characteristics are introduced to describe laser damage to materials in the multiple-exposure regime. The possible mechanisms of the cumulative effect are discussed. Experimental data are given on laser damage to optical polymer materials and these data demonstrate some of the fundamental laws governing this effect. Using the example of transparent polymers, methods for suppressing the cumulative effect are proposed and put into practice.