Anisotropic ZnS:Cr²⁺ crystal: material for compact and efficient mid-IR tunable lasers

A laser-quality anisotropic ZnS:Cr²⁺ element was obtained using prolonged hot isostatic pressing at high temperature. Lasing centered at a wavelength of 2.45 µm was obtained with longitudinal pumping at a wavelength of 1.94 µm. The short-cavity laser slope efficiency with respect to the absorbed power was about 78%. The lasing wavelength was continuously tuned in the range of 2.35-2.52 µm by rotating the Brewster active element around the normal to its surface.