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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.

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.

Report presented at the International Seminar on Present Status and Future Plan of Inertial Confinement Fusion, Tokyo, Japan, 26 November 1992.

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.

Output characteristics of a pulsed e-beam controlled discharge laser operating at the first-overtone (FO) transitions ((Delta) V equals 2) of CO molecule 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 micrometers on vibrational transitions from 6 yields 4 up to 37 yields 35. Maximum output efficiency 11%, the highest of eve laser, has been experimentally obtained for the broad band multiline FO CO laser. Maximum specific output energy (SOE) is 50 J/I Amagat. FO CO lasing was observed within an initial gas temperature interval 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%. The experiments with pulsed FO CO laser using diffraction grating as a frequency selective element demonstrated a feasibility of a development of frequency tunable single line pulsed FO CO laser. Tunable FO CO lasing on wavelengths from 2.7 up to 4.2 micrometers corresponding to vibrational transitions from 13 yields 11 up to 38 yields 36 was obtained. The maximum SOE came up to 2.8 J/I Amagat, 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 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.

Output characteristics of a pulsed e-beam controlled discharge laser operating on the first-overtone (FO) transitions (?V=2) of CO molecule 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 µm on vibrational transitions from 6?4 up to 37?35. Maximum output efficiency as high as 11% has been experimentally obtained for the broad band FO CO laser. Output efficiency of the laser operating on a few vibrational bands within the relatively narrow spectral range 2.5-2.7 µm comes up to 5% at entirely suppressed fundamental band (?V=1) lasing. FO CO lasing was observed within an initial gas temperature interval 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%.

The theoretical, technical and technological aspects of the high energy and low angular divergence laser beam obtaining by means of Raman's scattering application in the secondary cascade are discussed. Several (2 - 6) unphased, independent, simultaneously working primary cascades were combined into one laser beam having 10 cm diameter and 10 15 - 10 16 W/cm 2 .sterad brightness at 40% summing efficiency.

The results of research on decrease in angular divergence of radiation of explosively pumped photodissociation lasers (EPPL) with the use of the method of phase conjugation for compensation of active medium optical nonuniformities and distortions of laser beam during its propagation through the atmosphere to an object of influence are presented.

The operation of laser system based on explosively pumped photodissociation lasers and designed to control the distribution of space debris not observed nowadays is described and the possibility of its breaking using laser radiation effect and its subsequent evaporation in the Earth's atmosphere is discussed.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The principle of operation of explosively pumped lasers and variants of its construction are described, values of parameters achieved in practice are presented.

Comparative analysis of gas lasers pumped by γ‐radiation for ignition experiment is carried out. The possibilities of frequency‐time pulse shaping are discussed for these kinds of laser drivers. New type of ICF target (LIGHT‐target), which is able to provide an uniform deposition of laser driver energy is proposed as a target for ignition experiment.

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%.

A study was made of the efficiency of conversion of target-heating laser radiation into x rays emitted by a plasma in a wide range of laser radiation power densities (5×1011–2×1014 W/cm2) and atomic numbers of the target material (4–92). Estimates were obtained of the exposure dose needed for x-ray photolithography of resists when such a laser-plasma source of soft x rays was used.

A study was made of wavefront reversal, accompanying stimulated Brillouin scattering in various media, and of the way it was affected by the geometrical, temporal, and polarization characteristics of the exciting radiation. In an oscillator-amplifier system, practically complete compensation was achieved for phase distortions of the oscillator signal introduced by the amplifier components. The output energy of the light beam was then 3 J, its diameter was 4 mm, and its divergence (diffraction limited) was 0.3 mrad. The results of the experiments indicated a practical possibility of applying the wavefront reversal phenomenon in high-power multichannel lasers.

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.

A theory is proposed for the acceleration, heating and compression of a double-shell target exposed to a laser pulse. It is shown that in the hydrodynamic regime the inner shell may be accelerated to velocities of ~200 km/sec, the energy density in the central stage may be increased whilst maintaining a high plasma density, and ultimately an inhomogeneous laser plasma configuration may be achieved, this being required for the evolution of a self-sustaining wave of fusion reactions. Depending on the aim of the experimental investigations (achieving a high plasma density or temperature), various systems for matching the parameters of a double-shell target with the characteristics of the laser pulse are proposed.

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 investigation is made of the reflection of a mulitfrequency signal in connection with wavefront reversal in four-wave interaction. When the signal and reference waves are generated by a single source and their optical paths are matched, it has been established experimentally and theoretically that if the length of the medium is greater than the coherence length, the reflection efficiency is the same as that for monochromatic waves of the same intensity. For a short medium, fluctuations of the intensity of many nonphase-matched spectral components should increase the reflection efficiency up to sixfold.

Experiments are described on multiplying the frequency (7.4×1010 Hz) of a klystron and mixing the multiplied frequency with radiation of frequency 3.6×1012 Hz from a D2O laser. The nonlinearity of superconducting point contacts and the experimental method employed made it possible to multiply and mix at frequencies exceeding several times the ultimate frequency, and to investigate the mixing mechanism. The amplitude of the beat signal between the laser radiation and the multiplied klystron frequency was proportional to the differential resistance of the contact. Over a wide range of contact bias voltages, the frequency of the beat signal was independent of the Josephson emission frequency. No substantial difference was discovered between the nonlinear properties of the contacts at frequencies of 1010 and 3.6×1012 Hz. It was found that superconducting point contacts enabled a considerable simplification to be made in the frequency synthesis chain of an He–Ne laser by excluding several klystrons, metal–oxide–metal diodes, and a bulky submillimeter HCN laser.

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.

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.

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 energy balance of a laser thermonuclear reactor is considered and it is shown that the energy of the reaction products absorbed by the focusing optics of the reactor considerably exceeds the energy absorbed from the laser pulse. The x-ray spectrum of the target emission is calculated and used to find the minimum distances from the center of the chamber to the optical system. Variants of the gas shield are analyzed. The laser radiation brightness required to ignite the reaction is used to obtain a relationship between the minimum focal length and the optical strength of the material employed for the optics. It is shown that thermonuclear neutrons incident on the focusing system generate considerable thermal stresses and deformations.

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.

The construction principle and the applicable system are considered for the highpower laser amplifier module of the “Del'fin” facility, intended for spherical heating of thermonuclear targets. Results are presented of investigations of the radiation parameters of the amplifier module under various operating regimes. The system for focusing the laser radiation on the target surfaces is described and the results of experiments on plasma heating by radiation of three composite laser beams, at a laser energy level up to 1 kJ at a flux density up to 1014 W/cm2, are analyzed.

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.

Measurements were made of the divergence of radiation from electron-beam-controlled CO and CO2 lasers for closely similar pump conditions and resonator parameters. It was found that for the long pulse durations and the broad laser emission spectrum of the CO laser the divergence of the radiation due to individual vibrational–rotational transitions differed by a factor of three, the lowest divergence being realized after the end of pumping at the moment when a linear profile of the active medium density is established. Small-scale filamentary inhomogeneities were discovered during pumping of a CO-laser active medium cooled to cryogenic temperatures. The divergence of the CO2 laser radiation was approximately the same as that of the lines from the CO laser having the greatest angular width.

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-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%.

This paper describes the evolution of a concept for a technological laser for industrial use. It consists of a collation of texts published by the authors and their colleagues in the U.S.S.R. over the past decade. A laser system which can run on multiple wavelengths, operate in CW, and long or short repetitive pulse modes, and which can operate economically was the design goal. Each section of this paper addresses one of the problems to be solved and indicates how it was solved. The end result is a laser system which uses a coupled turbocompressor and refrigerator to supply the gas flow and temperature control. The gas which expands and cools in the refrigeration turbine also supplies a portion of the power required by the turbocompressor. This system can operate on CO or CO 2 , thus serving as a source of mid-and far-infrared radiation in either the CW or pulse repetition mode. A five gas mixture (to conserve helium) and a silica gel gas purifier (in place of a catalytic converter) are proposed for their economic advantages.

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 combination scattering of the probing radiation in laser spherical heating experiments performed with the Kalmar laser system was investigated. The second harmonic of an Nd laser was used for plasma probing. The frequencies 3 2 ω 0 , 5 2 ω 0 and 3ω0 (where ω0 is the frequency of the Nd laser) in the plasma radiation spectrum were measured. The possibility to determine the plasma turbulence spectrum from the scattered light is demonstrated.

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.