High-energy room-temperature Fe²⁺:ZnS laser

Characteristics of a room temperature laser on polycrystalline ZnS:Fe²⁺ subjected to diffuse doping from two sides were investigated. The sample was pumped by a non-chain electrodischarge HF laser with the FWHM duration of the radiation pulse of ∼140 ns. The diameter of the pumping radiation spot on the surface of the crystal was 3.8 mm. Further increases in the size of the pumping spot were limited by parasitic generation arising due to a high concentration of Fe ions in the near-surface layer of the sample at a relatively small depth of doping (short length of active medium). The generation energy of 25.5 mJ was obtained at a slope efficiency of 12% with respect to the energy incident on the sample. Characteristics of lasers on polycrystalline ZnS:Fe²⁺ and ZnSe:Fe²⁺ have been compared in equal pumping conditions. The slope efficiencies of ZnSe:Fe²⁺ and ZnS:Fe²⁺ lasers with respect to the absorbed energy were 34% and 20%, respectively. At equal pumping energy absorbed in the samples, the duration of the ZnSe:Fe²⁺ laser radiation pulse was longer than that of the 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 the pumping pulse are discussed in this letter. (letter)