Lasing Characteristics of Fe:Cr:ZnSe Polycrystals

Abstract

The characteristics of a laser based on Fe:Cr:ZnSe polycrystals, excited at room temperature by a non-chain HF laser (2.6 to 3.1 µm) have been investigated. High-temperature diffusion doping of zinc selenide (CVD ZnSe plates) with chromium and iron was applied. Two active elements were studied. In one of them, iron and chromium were introduced into the crystal through one of the ZnSe plate surface; i.e., the Cr²⁺ and Fe²⁺ concentration profiles were overlapped in the crystal. When fabricating the second element, iron and chromium were introduced from the opposite plate surfaces, and their concentration profiles were spaced. It is established that co-doping of zinc selenide with chromium and iron reduces significantly the slope efficiency and increases essentially the lasing threshold with respect to the absorbed energy in comparison with similar parameters of lasers based on Fe²⁺:ZnSe crystals, fabricated by the same technology. One of the main causes of the deterioration of lasing characteristics of the Fe:Cr:ZnSe laser in comparison with the Fe²⁺:ZnSe laser is the absorption of radiation at the lasing wavelengths in the range of 4 to 5 µm in chromium-containing crystals. The prospects of designing a laser with an active element operating at room temperature, in which iron ions should be excited due to the energy transfer from chromium ions, are discussed.