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The gain dynamics in the active medium of an overtone CO laser operating on the transitions between high vibrational levels is studied experimentally and theoretically. The gain dynamics is measured on the vibration — rotation transitions of the CO molecule [the P(12) spectral line in the vibrational bands from 20 → 18 to 36 → 34] in CO — He and CO — N2 laser mixtures. The maximum small-signal gain was 0.43 m-1. The theoretical model of the CO laser was significantly improved. It was shown that multiquantum and asymmetric VV-exchange processes should be included in the analysis of the population dynamics of high vibrational levels of the CO molecule.

Characteristics of a pulsed, multifrequency electroionisation CO laser operating on the first vibrational overtone of the CO molecule are studied experimentally and theoretically. It is shown experimentally that a pulsed, multifrequency overtone CO laser is an efficient source of coherent radiation in the 2.5–4.1-μm region whose specific output reaches 50 J l-1 amagat-1 and the electro-optical efficiency amounts to 11 %. A theoretical analysis based on experimental data shows the feasibility of obtaining overtone emission with efficiency as high as ~20 %. The alternation of the intensity of vibrational bands in the overtone CO laser is discussed. This effect is caused by the cascade mechanism of formation of the emission spectrum. The comparison of experimental data with calculations showed that they agree well with respect to spectral and energy characteristics of the overtone CO laser. Moreover, it revealed the necessity of refinement of the kinetic model of the active medium of the CO laser for obtaining an adequate description of time parameters of a laser pulse.

Output characteristics of a single-pulse e-beam controlled discharge laser operating on the first-overtone (FO) transitions (/spl Delta//spl nu/=2) of CO molecules have been studied both experimentally and theoretically. Various sets of dielectric mirrors with high reflectivity in the range of the overtone spectrum have been used for the laser resonator. Multiwavelength lasing has been obtained in the wide spectral range of 2.5-4.1 /spl mu/m on vibrational transitions from 6/spl rarr/4 up to 37/spl rarr/35. A maximum output efficiency of 11%, the highest ever published for a FO CO laser, has been experimentally obtained for the broad-band multiline FO CO laser. Maximum specific output energy is 50 J/1 Amagat. FO CO lasing was observed within a predischarge gas temperature range of 100-220 K. Spectral characteristics of the overtone laser operating on a selected set of vibrational bands have been analyzed theoretically. Theoretical calculations based on the experimental data predict that multiline FO CO laser efficiency can be increased up to 20%. Experiments with a single-pulse FO CO laser using a diffraction grating as a frequency-selective element demonstrated the feasibility of developing a frequency-tunable single-line FO CO laser. Tunable FO CO lasing on wavelengths from 2.7 up to 4.2 /spl mu/m corresponding to vibrational transitions from 13/spl rarr/11 up to 38/spl rarr/ 36 was obtained. The maximum specific output energy came up to 2.8 J/1 Amagat, with single-line output efficiency being up to 0.6%.

Tunable single-line first-overtone (FO) CO lasing on wavelengths from 2.7 up to 4.2 μm corresponding to overtone vibrational transitions from 13→11 up to 38→36 on 413 ro-vibrational lines was experimentally obtained. A parametric study of energetic and spectral characteristics of the single-line FO CO laser was carried out. Energy distribution over ro-vibrational lines was measured. The maximum specific output energy (SOE) came up to ∼3 J/l Amagat, with single-line output efficiency being up to 0.6%. For the first time, a multi-quantum theoretical model was used to describe the tunable single-line FO CO laser. This multi-quantum approach demonstrated better agreement between theoretical calculations and observed experimental data for laser output as a function of vibrational quantum numbers.

Output efficiency as high as 11% and specific output energy up to ∼50 J/l Amagat were experimentally obtained for a cryogenically cooled multiline pulsed first-overtone (FO) CO laser for the first time. The longest generated wavelength was 4.1 μm, corresponding to the 37→35 vibrational transition. FO CO lasing was observed within an initial gas temperature interval of 100–220 K. Theoretical calculations based on the experimental data predict that the FO CO laser efficiency can be increased up to 20%. High efficiency and high specific output energy obtained in the experiment places the FO CO laser amongst other high-power lasers.

Targets with low degrees of compression, such as those with internal energy deposition, two-stage conical targets for lasers emitting pulses of duration of the order of 100 ns, and multilayer shell targets for short-pulse long-wavelength CO2 and CO lasers may prove acceptable for hybrid thermonuclear reactors with high values (of the order of 103) of the gain in the blanket. Estimates and one-dimensional calculations of the compression of such targets are reported for the laser radiation energy range 0.2–2 MJ.

A high-power KrF laser system was developed on the basis of a large-aperture excimer laser with electronbeam pumping and injection control by an electric-discharge master oscillator. The spectral brightness of the radiation of line width ~0.1 cm-1, tunable near λ = 248 nm, was ~5 × 1014 W cm-2 sr-1 per cm-1 at a peak power of ~1 GW.

A superlattice with strained ZnCdSe/ZnSe layers was grown by the method of molecular beam epitaxy. This superlattice was used as the active layer in the screen of a laser cathode-ray tube. The room-temperature output power was 1.6 W in the form of one longitudinal mode at the 484 nm wavelength. The earlier results obtained at electron energies below 50 keV were improved.

Tunable single-line first-overtone (FO) CO lasing on wavelengths from 2.7 up to 4.2 micrometer corresponding to overtone vibrational transitions from 13 yields 11 up to 38 yields 36 on 413 ro-vibrational lines was experimentally obtained. A parametric study of energetic and spectral characteristics of the single-line FO CO laser was carried out. Energy distribution over ro-vibrational lines was measured. The maximum specific output energy (SOE) came up to approximately 3 J/l Amagat, with single-line output efficiency being up to 0.6%. For the first time, a multi-quantum theoretical model was used to describe the tunable single-line FO CO laser. This multi-quantum approach demonstrated better agreement between theoretical calculations and observed experimental data for laser output as a function of vibrational quantum numbers.

Three primary colors (red -- 620 nm, green -- 540 nm, blue -- 455 nm) are obtained by means of A2B6 e-beam pumped semiconductor lasers. Semiconductor plates 5 cm in diameter are used. Light output in white is 3000 lm (9 W). High resolution (up to the 2000 pix/line) gives us the possibility of using such an L-CRT projector in HDTV. The main characteristics of basic elements are given. It is possible to reach the L-CRT light output of 104 lm.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A high-power KrF laser system based on a wide-aperture electron-beam pumped excimer laser `GARPUN' with injection-locking from a discharge pumped narrow-band oscillator has been developed. The laser radiation spectral brightness of approximately 5 X 1014 W/cm2 srad cm-1 with narrow linewidth approximately 0.1 cm-1 tunable near (lambda) equals 248 nm, and the output peak power of approximately 1 GW have been obtained.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A fine-aperture excimer laser module called the Garpun was constructed with an active region of 18 × 20 × 100 cm dimensions. It was pumped from two sides by high-current electron beams. When the laser was pumped by pulses of 100 ns duration and 2 × 25 A/cm2 current density, the output energy of a F2–Kr–Ar mixture was 60 J and the peak power is 1 GW.

A report is given of the construction of a high-pressure (N = 0.4–1.1 amagat) pulse-periodic electron-beam-controlled CO laser with a pump pulse-repetition frequency f of up to 120 Hz. It is shown that, for N = 0.4 amagat (T ≈ 120 K), the lasing characteristics are not impaired right up to f0/f = 1.2 (where f0 is the maximum frequency). The average specific laser output power per unit active volume is ~ 2 kW/liter with an efficiency of 14%.

The effects arising from the action of radiation from a laser operating in the free generation mode on optical glass are studied. The method of velocity interferometry is employed to establish that, when the laser radiation is focused within the specimen, optical inhomogeneities arise within the latter. The magnitudes of these inhomogeneities within the caustic of the focusing lens are measured. On the basis of the time lapse required for the rise of such inhomogeneities, the proposition is made that they are caused by thermoelastic stresses. Using the methods of thermoelasticity, the magnitudes of these strains and the temperature are calculated. It was also discovered that focusing the radiation on the surface of the sample produces evaporation of the specimen material. A qualitative description is given, and this effect is compared to the surface evaporation which occurs under laser action on condensed opaque media.

An experimental investigation was made of stimulated emission from stimulated Brillouin scattering (STBS) lasers in which one of the mirrors was of the self-pumped parametric type. The lasing threshold of a ring laser was found to be five times less than that of the conventional backward STBS. The duration of the linear stage of the development of lasing was measured for various values of the excess above the threshold and for different resonator lengths. Even when the resonator length was characterized by a Fresnel number ~ 1, the divergence of the radiation generated by a parametric laser was 1.5 times higher than the divergence of the pump radiation. The pump conversion efficiency was estimated theoretically for the steady-state operation. The theoretical dependence of the reflection coefficient on the pump intensity was confirmed experimentally. A phase conjugation method with a high energy efficiency was proposed and implemented.

An analysis is made of the problems involved in operating and using two-mode low-power cw gas lasers in nonlinear laser spectroscopy and metrology. The high sensitivity to weak lines of the saturated dispersion makes two-mode nonlinear laser spectroscopy one of the most promising methods for the detection of optical resonances of up to 100 Hz wide and for the development of optical frequency standards having a reproducibility of 10−14–10−15.

A theoretical investigation is made of the electronic structure of levels of ionic heteronuclear molecules consisting of atoms and ions of rare gases, halogens, elements of the oxygen group, and alkali metals. The electronic transitions promising for lasing in the visible, ultraviolet, and far ultraviolet (? 70 nm) spectral ranges are identified. A method is proposed for the attainment of lasing as a result of electronic transitions in multiply charged ionic molecules of the Li+ +Li ?Li+Li+ type (? ~ 20nm).

A new class of chemical lasers based on electronic transitions of atoms, radicals, or molecules excited via oxidation chain reactions in the presence of catalysts is proposed and discussed. The possibility is considered of using these processes to realize four lasing schemes: directly via transitions of excited intermediate products, in an exchange chemical laser, using narrowband “chemical lamps,” and in chemical-excimer lasers. A number of specific active mixtures are proposed. The gain of a realizable chemical Na-BaOlaser is calculated. The possibility of using chemical reactions with participation of cluster molecules are analyzed. The use of atoms as acceptor (emitting) particles is discussed. Two methods of obtaining increased atom densities are proposed. Certain possibilities of obtaining cw lasing on self-limiting atom transitions are considered.

The characteristics of XeF and XeCl lasers stabilized by an external low-power ionizer were considered. Two laser operating regimes were investigated, one with a buildup of negative ions and the other with a discharge stabilized by an external low-power ionizer. The temporal, spectral, and energy characteristics of these lasers were investigated. The minimum ion concentration in the negative-ion buildup regime was found to be [F−]=1011cm−3 and [Cl−]=1012cm−3, while the use of a discharge stabilized by a low-density electron beam made it possible to reduce the current density of the electron beam to ~0.1mA/cm2 in the case of the XeCl laser. A value of 10 J/liter was achieved for the maximum specific output energy of the XeCl laser.

An experimental investigation was made of the dependences of the output energy and efficiency of a pulsed electron-beam-controlled laser utilizing the first overtones of the CO molecule on the power and energy of excitation, characteristics of the active gas mixture, and Q factor of the resonator. In an apparatus having an active volume of 4 liters, a CO–N2–He gas mixture was excited and specific output energies of around 10 J/liter−1amagat−1 were realized at an efficiency of ~ 5%. It was found that in order to achieve high laser energy characteristics one must suppress lasing at the fundamental frequencies and use long relatively low-power pump pulses. A qualitative explanation is put forward for the observed behavior.

A new class of chemical lasers utilizing electronic transitions in atoms, radicals, or molecules excited as a result of oxidation chain reactions in the presence of a catalyst is proposed and analyzed. The possibilities for using these processes to achieve four lasing schemes are discussed: directly due to transitions in excited intermediate products, in an exchange chemical laser, using narrow-band "chemical lamps," and in chemical excimer lasers. Various specific active mixtures are proposed to achieve electronic-transition chemical lasers with a chain excitation mechanism.

Possible methods of achieving pulse-periodic operation of an oxygen?iodine chemical laser (OICL) are indicated. The energy characteristics and efficiency of the pulse-periodic regime are improved substantially if atomic iodine is prepared rapidly in a singlet oxygen medium. This can be done by flash ultraviolet photolysis of iodides. An analysis is made of a system for generation of single nanosecond pulses in an OICL, incorporating a multipass ring amplifier. Coherent amplification conditions can be achieved in this system and the energy stored in the upper level of the iodine atom can be extracted with a 95% efficiency. Estimates show it is realistic to obtain an energy of around 100 kJ, so that the proposed system is potentially useful for laser fusion applications.

The effect of small-scale wavefront perturbations on laser radiation is investigated at flux densities close to maximum. The model and calculated results for the effect of the degree of radiation coherence on the laser radiation brightness as functions of flux density and length and shape of the active medium are presented. For the restricted coherence of the laser radiation, the rate of small-scale perturbation growth is shown to decrease in theactive medium. The principal optical scheme of a laser for fusion experiments, with the maximum radiation brightness, is given as an example.

A description is given of the first mercury halide photodissociation laser pumped by wide-band thermal radiation from a plasma and emitting three-color visible radiation. Simultaneous lasing was observed for ionic-covalent electronic B–X transition in molecules of mercury monochloride λl≈558 and 559 nm, monobromide (λl≈502 and 504 nm), and monoiodide (λl≈443 and 444 nm). The laser radiation energy was ~0.3J emitted in the form of ~2.5μsec pulses and the lasing efficiency was ~0.07%.

The feasibility is investigated of chemical generation of electron-excited molecular nitrogen N2(A, B) and of its use as a donor for the development of short-wave chemical lasers. The spectroscopic and kinetic properties of the molecules as potential acceptors of the excited-nitrogen energy are discussed. The feasibility of producing a chemical N2(A)-IF laser for the visible band (λ = 625 nm) is investigated analytically and numerically. The amplification properties of the active medium are analyzed and the energy characteristics of the laser are calculated.

The thermodynamic gasdynamic parameters of the active media of subsonic and supersonic open- and closed-cycle electron-beam-controlled lasers (EBCL) are theoretically calculated. The optimal characteristics of the pumping system and of the thermal regimes of the active medium, which permit a considerable improvement of the energy characteristics of the EBCL, are calculated. The investigations make it possible to increase the efficiency and the working-medium pressure of cw electron-beam-controlled lasers and decrease the dimensions of the laser installations.

The results are given of an experimental study of the tuning of the emission frequency of an electron-beam-controlled CO2 laser operating at pressures up to 8 atm. These results are obtained for a wide range of nitrogen concentrations (10–80%) in CO2 + N2 mixtures. The emission frequency can be tuned by 0.4 cm–1 within pressure-broadened vibration-rotational transitions in a mixture of 1 part CO2 and 2 parts N2 at a pressure of 8 atm. Estimates are given of the parameters of an electron-beam-controlled CO2 laser in which a continuous tuning of the emission frequency should be possible between several overlapping P- and R-branch lines.

A detailed experimental investigation was made for the first time of the time-resolved spectral and energy characteristics of a pulsed electron-beam-controlled CO laser, as a function of the water vapor content in an intracavity cell. It was found that using such a cell made it possible to considerably increase the number of rotational lines in the emission spectrum and thereby to extend the tuning range of the emission frequency of a pulsed electron-beam-controlled CO laser. The introduction of water vapor into the resonator made it possible to match the emission spectrum of such a laser to the atmospheric transparency windows in the range 5–5.5 μ. The possibility was investigated of utilizing a column of atmospheric air as a selective absorption cell.

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.

Lasing was obtained in the blue-green spectral region (λ ~ 480 nm) due to the C-A transition in the XeF* molecule pumped by excimer radiation in the vacuum ultraviolet spectral region. The spectral and energy characteristics of the spontaneous and stimulated emission were investigated as functions of the buffer gas (argon and nitrogen) pressures. The possibility was investigated of constructing a laser emitting in the blue-green spectral region by pumping a Kr-XeF2 mixture with no separation between the excitation and lasing zones.

A study was made of a high-power high-pressure electron-beam-controlled laser utilizing the 5d-6p and 7p-7s transitions of the Xe atom and having an active volume of 9 liters. The dependences were obtained of the electrical parameters of an electron-beam-controlled discharge and of the energy parameters and spectral composition of the output radiation on the type of buffer gas, the discharge circuit parameters, and the composition and pressure of the active mixture. When the medium was pumped by an electron beam alone, having a current density of ~ 6 A/cm2 and a pulse duration of O.7 μsec, the laser output energy was ~ 6/J (efficiency ~ 1.5%), but for electronbeam- controlled pumping it was roughly 20 J. The physical lasing efficiency, in terms of the electric field, was ~5%. An analysis was made of the mechanism of the establishment of the active medium conductivity and of the population kinetics of the active transition levels.

A study was made of a high-pressure pulsed laser utilizing 3d?4p transitions in the Ar atom and emitting at wavelengths of 1.27, 1.79, 2.08 and 2.40?. When a 10-liter He?Ar active mixture was pumped by a beam of fast electrons, the output energy was 0.8J and the laser efficiency was > 1%. The electron-beam-controlled excitation method was realized for the first time in the case of He?Ar and Ne?Ar mixtures and the output energy was 1.5J. A study was made of the spectral composition of the radiation as a function of the experimental conditions.

An investigation was made of the spectral and energy characteristics of stimulated and spontaneous radiation emitted by an Ar+N2 mixture excited by an electron beam. The maximum specific output power (~70 kW/cm2) was obtained when the pressure in an Ar:N2 = 10:1 mixture was about 8 atm. The efficiency of conversion of the electron-beam energy into the stimulated radiation energy at λ = 357.7 nm wavelength reached up to ~3%.

Experimental investigations were made for the first time of the amplification of a multifrequency radiation pulse generated by an electron-beam-controlled CO laser in the multilevel active medium of an electron-beam-controlled CO amplifier. A value of ~30 J liter −1 amagat −1 was achieved for the specific output energy of the amplifier. The effective saturation energy was determined and was found to be roughly 5–10 J cm −2 amagat −1 for the conditions of the experiment (τp 150μsec).

The first experimental investigation was made of the threshold, energy, temporal, and spectral characteristics of a pulsed cooled electron-beam-controlled laser utilizing pure carbon monoxide. The experiments were carried out in a system having an active volume of ~5 liters at an active gas temperature of ~100°K and a density up to 1.0 amagat. The excitation duration was varied in the range 30-300 μsec. Laser action was observed in the spectral range 5.1–5.5 μ and, as the pump energy was increased, the spectrum broadened into short-wavelength range. It was found that the efficiency of an electron-beam-controlled pure carbon monoxide laser did not exceed 10%. The measured parameters of the electron-beam-controlled carbon monoxide laser did not agree with the results of theoretical calculations.

It is shown that precooling the active mixture in a cw electron-beam-controlled CO2 laser makes it possible to raise considerably the optimal operating pressure (by a factor of 5–10) and the output energy per unit volume (by a factor of 3–5). A scheme is proposed in which a refrigerating unit is incorporated within the gasdynamic loop. This scheme enables laser systems of greatly reduced size to be produced.

Experimental results on the compression of shell targets with aspect ratio A = 150–250 in the “Delfin-1” installation are reported. The absorbed laser energy was 0·3 to 0·5 kJ. The maximum compression was 3·5 × 103, the velocity of target compression at the final stage was 2·6 × 107 cm/s, neutron yield was 106 to 107 D-D neutrons per laser shot. The appearence of plasma corona filamentation correlated with compression stability distruction.

An analysis is made of the feasibility of increasing the spectral emission range of chemical lasers utilizing electronic transitions. The chemical excitation processes are classified, the main kinetic schemes of donor–acceptor lasers are discussed, and the laser efficiency is estimated. A new class of reactions is proposed as a potential source of electronically excited nitrogen molecules for short-wavelength chemical lasers. Various types of chemical processes involving the generation of singlet oxygen are discussed. A homological series of donor–acceptor pairs potentially suitable for use in exchange lasers (spectral emission range 0.2–1 µ) is proposed.

It is shown theoretically that a new family of gas lasers utilizing ionic heteronuclear molecules can be constructed for emission of visible, ultraviolet, and far ultraviolet radiation.

A description is given of a new method for generating high-power nanosecond pulses with steep leading edges and a high contrast. The method makes it possible to obtain beams with large transverse cross sections in a neodymium-glass laser system.

An analysis is made of the principal thermodynamic, spectroscopic, kinetic, and radiative characteristics of halogen and interhalogen compound molecules as active media in chemical lasers, and of corresponding quasiresonant donor partners in the form of metastable radicals. The chemical processes generating electronically excited donor particles, including a new class of reactions involving alkali metal atoms, are given. Specific, most promising donor–acceptor pairs are identified. Estimates are obtained of the threshold density of the population inversion needed for lasing. A systematic analysis is made of the processes of formation of electronically excited I(2P1/2) iodine atoms and O2(a1Δ) oxygen molecules which are of interest as auxiliary donors. Several kinetic schemes for initiation of pulsed NF–I2 lasers are discussed. A specific scheme for a NF–I2 chemical laser emitting in the visible range is proposed.

Investigations were made of the magnitude and distribution of the population inversion, homogeneity of the medium, and influence of an amplifier on the master-oscillator pulse contrast. It was found that the population inversion distribution was strongly inhomogeneous. The active medium in the amplifier was very homogeneous and ensured a divergence of 10–4 rad. The iodine amplifier had a negligible (for the contrast) luminescence noise level.

An analysis is made of the stimulated emission due to electron transitions in the Xe2 molecule as a result of excitation by the electron-beam-controlled method. A numerical solution is obtained of the transport equation for the electron energy distribution function in high-pressure xenon subjected to a static electric field. The excitation rates of electron levels of Xe are calculated. The computed efficiency of the conversion of the pump energy into radiation may reach 65–75%. Theoretical estimates are obtained of a population inversion and gain in the vacuum ultraviolet as a result of electron-beam-controlled excitation. In an experimental study, stimulated emission at λ=172.5 nm was obtained as a result of pumping with a fast-electron beam. An investigation was made of the spectral and energy characteristics of the spontaneous and stimulated radiation. The efficiency of electron-beam pumping of Xe compressed to 16 atm was ~15%. The energy input into the gas in an electron-beam-controlled method was measured. The degradation of the active medium was investigated in the two cases of the excitation by the electron-beam-controlled method and the pumping with an electron beam.

The frequency of a two-mode He–Ne laser (λ =3.39 μ) with an intracavity telescopic beam expander was stabilized for the first time using resolved magnetic hyperfine structure components of the methane F2(2) line, selected by the highly sensitive method of frequency detection of saturated dispersion resonances. Investigations were made of the stability and shifts of the laser frequency as functions of various physical parameters. Operating conditions were found for minimizing the shifts in the stabilized frequency over a wide range of parameter variations. The long-term frequency stability of the radiation emitted by a compact twomode laser with a telescope was found to be 2×10−14 for a 100-sec averaging time, while the shifts in the stabilized frequency did not exceed a few hertz over a wide range of variation of the main parameters.

A method was developed for the calculation of the energy parameters of an electron-beam-controlled CO$sub 2$ laser. An experimental study was made of the output energy, efficiency, pulse shape, and duration of the radiation emitted by a 10-liter CO$sub 2$ laser as a function of the composition of the mixture, electron-beam pump power (pulse duration 1--50 $mu$s), and electric field in the active medium. The calculation method gave results which were in quantitative agreement with the experimental data. (AIP)