Tellurium and sulfur doped GaSe for mid-IR applications

Centimeter-sized Te:GaSe (a parts per thousand currency sign10 mass%) ingots have been grown by the vertical Bridgman technique and studied to reveal the potentials for phase matching and frequency conversion. Less than 5 mass% Te-doped crystals show the hexagonal structure like epsilon-GaSe. Te:GaSe (a parts per thousand currency sign2 mass%) crystals were suitable for non-linear applications. The optimal Te-doping level between 0.1 and 0.5 mass% has been clearly observed in CO2 laser SHG experiment. The CO2 laser SHG efficiency in Te:GaSe (0.1-0.5 mass%) is similar to 20 % higher than that of GaSe due to better optical quality. Phase matching conditions in Te-doped crystals have been shown to be identical with those of GaSe.