The energy and spectral-temporal characteristics of a Fe : ZnSe laser operating in pulsed and repetitively pulsed regimes are studied at room temperature of the polycrystalline active element. The crystal was pumped by a nonchain electric-discharge HF laser. The energy of the Fe : ZnSe laser in a single-pulse regime was 1.67 J at the slope efficiency with respect to the absorbed and incident energy of ∼43% and ∼27%, respectively. In a repetitively pulsed regime with a pulse repetition rate of 20 Hz and an efficiency with respect to the absorbed power of ∼40%, the average laser power was ∼20 W with an individual pulse energy of ∼1 J. The possibility of increasing the average power of the repetitively pulsed Fe : ZnSe laser at room temperature is discussed.

Efficient generation of a train of laser pulses is obtained at room temperature in a Fe2+: ZnSe polycrystal pumped by a passively Q-switched Er:YAG laser. The Fe2+:ZnSe laser energy reaches 130 mJ at a slope efficiency with respect to the absorbed pump power of 47%. The average pulse repetition rate in the train is ∼100 kHz.

The characteristics of a laser based on a Fe2+ : ZnSe single crystal pumped by an electric-discharge HF laser at room temperature are studied. The HF laser beam diameter on the crystal surface was 17 mm. The achieved laser energy was 1.2 J with an efficiency of similar to 25 % with respect to the pump energy.

Experimental results on a solid-state holmium laser (Ho : YAG) with an intracavity acousto-optic paratellurite filter are presented. The laser power in cw and repetitively pulsed regimes is determined experimentally. It is shown that the use of an acousto-optic filter in the Ho : YAG laser cavity makes it possible to solve several important problems such as obtaining repetitively pulsed lasing, wavelength tuning and linearly polarised emission.

A room-temperature laser based on a Fe2+ : ZnS single crystal has been studied. The crystal was pumped by a nonchain electric-discharge HF laser with a light pulse FWHM of similar to 140 ns. The pump spot diameter on the crystal surface (d) varied from 3.9 to 11.6 mm. The slope efficiency at these values of d was 37%-39 %, respectively. The maximum laser energy was 380 mJ (at d = 11.6 mm) with the total efficiency with respect to the absorbed pump energy of similar to 19 %. A further increase in the laser energy was not achieved because the crystal was destroyed at an incident pump energy and power of 3.4 J and similar to 24 MW, respectively. The damaged region has a form of a long narrow channel shifted from the entrance surface inside the active element.

The numerical modeling and the experimental research of the Ho: YAG system are done, which consists of the master oscillator and three power amplifiers. The doping level influence of the active elements on the laser oscillator work is researched. The conversion efficiency of the pumping reached 10% when the pulse repetition rate was about 100 Hz. The beam propagation-factor is ~ 1.3.

Operation of a repetitively pulsed electric-discharge HF(DF) laser with an all-solid-state pump generator based on FID switches is demonstrated. The energy stored in the pump generator capacitors was 880 J at an open-circuit voltage of 240 kV and a discharge pulse repetition rate of 25 Hz. The specific energy extractions were 3.8 and 3.4 J L-1 for the HF and DF lasers, respectively. The possibilities of improving the output laser characteristics are discussed.

Pulse-periodic lasing at wavelengths of 2.8 and 3.3 µm is obtained in the Cr2+:CdSe single-crystal laser. In the region of 2.8 µm, the pumping conversion is 28% (more than 50% of the absorbed energy). In the region of 3.3 µm, lasing is achieved at several tunable narrow lines appropriate for using in remote lidars. The pumping conversion in this spectral region is more than 17% (more than 30% of absorbed energy).

The characteristics of a Fe : ZnSe laser pumped by a single-pulse free-running Er : YAG laser and a repetitively pulsed HF laser are presented. An output energy of 4.9 J is achieved in the case of liquid-nitrogen cooling of the Fe2+ : ZnSe active laser element longitudinally pumped by an Er: YAG laser with a pulse duration of 1 ms and an energy up to 15 J. The laser efficiency with respect to the absorbed energy is 47%. The output pulse energy at room temperature is 53 mJ. The decrease in the output energy is explained by a strong temperature dependence of the upper laser level lifetime and by pulsed heating of the active element. The temperature dependence of the upper laser level lifetime is used to determine the pump parameters needed to achieve high pulse energies at room temperature. Stable repetitively-pulsed operation of the Fe2+ : ZnSe laser at room temperature with an average power of 2.4 W and a maximum pulse energy of 14 mJ is achieved upon pumping by a 1-s train of 100-ns HF laser pulses with a repetition rate of 200 Hz.

A laser on single-crystal ZnSe:Fe2+ was investigated at room temperature. Pumping of the laser was performed by a pulsed electrodischarge HF laser. In experiments, the spot diameter of HF laser radiation incident to the surface of the crystal varied from 5.6 to 17 mm. Generation energy of similar to 1.2 J was obtained and the efficiency with respect to the energy arriving at the crystal was eta(in) approximate to 25%. The slope efficiency with respect to the energy absorbed in the crystal at large spot dimensions was eta(slope) = 45%.

The influence of gas temperature on the characteristics of a self-sustained volume discharge was studied in the working mixtures of a chemical oxygen - iodine laser with pulsed electric-discharge production of iodine atoms. In experiments, laser working mixtures were modelled by the mixture of air and iodide C2H5I. It was established that mixture heating is accompanied by an increase in the voltage across the discharge plasma and by a decrease in the discharge current. By varying the temperature of the mixture with the iodine content of similar to 2.7 % and initial pressure p = 12 Torr from 22 degrees C to 96 degrees C, the current amplitude falls by similar to 12 %, and at the instant corresponding to a maximal current the voltage raises by similar to 22 %. Such a change in the discharge characteristics is explained by a higher rate of electron attachment to vibrationally excited iodide molecules at elevated temperatures.

The characteristics of a Fe2+ : ZnSe laser in a scheme with transverse pumping by a nonchain electric-discharge HF laser at room temperature are studied. Doping of ZnSe crystals with Fe2+ ions was performed by diffusion simultaneously through two surfaces under the conditions of thermodynamic equilibrium. It is found that the Fe2+ : ZnSe laser pulses are modulated by short spikes (3 - 7 ns at half maximum at low pump energies), whose number decreases and modulation depth increases as the pump energy decreases to a threshold value. A laser pulse energy of 30.6 mJ is achieved at a pulse duration at half maximum of similar to 125 ns (at high pump energies); the possibility of a further increase in the energy of Fe2+ : ZnSe lasers pumped by nonchain HF lasers is discussed.

Generation characteristics of a pulse-periodic oxygen-iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic-resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L-1). At a high pulse repetition rate of laser pulses (50 - 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded.

Spectral and temporal characteristics of a ZnSe:Fe2+ laser with a nonselective resonator pumped at room temperature by the radiation of a pulse-periodical electrodischarge HF(DF) laser are studied. It was established that the spectral distributions of the energy and peak power of ZnSe:Fe2+ laser generation depend on a spectral composition of the pumping radiation. The spectra exhibit a line structure with spectral intervals between neighboring lines delta(lambda) approximate to 6.8 divided by 8.6 nm. The shape of the ZnSe:Fe2+ laser generation pulse is wavelength dependent. In a short-wavelength range, the pulse has the form of a peak with a duration of similar to 5 ns at half-maximum. At a longer wavelength, the peak is accompanied by a 'tail'. The duration and amplitude of the tail increase with wavelength, in a long-wavelength spectrum range, the peak actually becomes unnoticeable on a background of the 'tail'. The spectral dependence of the ZnSe:Fe2+ laser generation pulse's shape affects the positions of the energy and peak power maxima on the wavelength axis. The dynamics of ZnSe:Fe2+ laser generation under the pumping by the pulsed HF(DF) laser is discussed.

On 22 September 2013, Gennadii Alekseevich Kirillov – doctor of physical and mathematical sciences, professor, prominent scientist, first director of the Institute of Laser PhysicsResearch, deputy scientific director of the Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics' (RFNC-VNIIEF) – died at the age of 80.

We report the possibility of creating high-power nonchain electric-discharge HF lasers with an all-solid-state pump source. The maximum energy stored in the pump source capacitors based on solid-state FID-switches is 990 J for the open-circuit voltage of 240 kV. The pulse energy of 30 J is obtained in the hydrogen-containing SF(6) mixture at the electric efficiency of the order of 3%.

The research activities in creation of atmospheric pressure laser with the output of similar to 33 W, pulse repetition rate up to 2200 Hz, efficiency of similar to 1.6% (DF-laser) and the output of similar to 40 W, pulse repetition rate up to 2000 Hz, efficiency of similar to 2% (HF-laser)