Generation characteristics of laser on polycrystalline ZnSe:Fe2+ samples doped by the diffusion method have been investigated at room temperature under the pumping by an electrodischarge HF laser. With the sample doped from two sides (working surfaces) the obtained generation energy was E=253 mJ with the slope efficiency ηsl=33% and efficiency with respect to the absorbed energy ηabs≈28% at the elliptical shape of the pumping spot of dimension a×b=6.8×7.5 mm. It was established that possibilities of further increase of generation energy on samples of this type by increasing the pumping spot area (at a constant density of the pumping energy) are limited by developing parasitic generation that is inherent in lasers with disk geometry. First investigation results are presented for a laser on the polycrystalline sample produced by the technology capable of providing zero doping component concentration on the surface and a maximal concentration at the centre of the sample (sample with "internal doping"). Prospects are discussed for increasing the generation energy of ZnSe:Fe2+ laser at room temperature by developing multilayer samples on the bases of the doping technique mentioned.
This paper reports on first experimental study of a self-sustained volume discharge (SSVD) in c-C4F8. The discharge voltage and current oscillograms are taken over a wide range of gas pressures. How and why this discharge radically differs from that in other strongly electronegative gases is considered in terms of the theory of the vibrational relaxation in polyatomic molecules. For the first time an SSVD in c-C4F8 preheated by CO2-laser radiation has been investigated. The unusual behavior and temperature-dependent characteristics of this discharge are revealed. There is much discussion on the peculiarities of an SSVD in a preirradiated c-C4F8. To refine the static limiting field in c-C4F8 the static dielectric strength of c-C4F8 is measured on changing the gas pressure by nearly two orders of magnitude.
Characteristics of a laser on polycrystalline ZnS:Fe2+ subjected from two sides to diffuse doping at room temperature are investigated. The sample was pumped by a non-chain electrodischarge HF laser with the radiation pulse FWHM duration of ~140 ns. The diameter of pumping radiation spot on the surface of crystal was 3.8 mm. Further increase of the size of pumping spot was limited by parasitic generation arising due to a high concentration of Fe ions in the near-surface layer of sample at a relatively small depth of doping (short length of active medium). The output energy of ZnS:Fe2+ laser was 25.5 mJ at the slope efficiency with respect to the energy absorbed in the crystal of 20%. Characteristics of lasers on polycrystalline ZnS:Fe2+ and ZnSe:Fe2+ have been compared in equal pumping conditions. The slope efficiency of ZnSe:Fe2+ laser was 34%. At equal pumping energy absorbed in the samples, the duration of ZnSe:Fe2+ laser radiation pulse was longer than that of ZnS:Fe2+ laser. Possibilities of increasing the efficiency of ZnS:Fe2+ laser operation at room temperature by improving the technology of sample manufacturing and reducing the duration of pumping pulse are discussed.
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