Single crystals of thallium halides with optical losses below 10dB/km

Single crystals of KRS-5 and KRS-6 were prepared and investigated. The optical losses in these crystals were (0.8–1.4)x10^–5cm^–1 (3.5–6 dB/km) at the wavelength of 5.54μ, (1.7–2)x10^–5cm^–1 (7.4–9 dB/km) at 10.6μ, and 10^–5 cm^–1 (4.2 dB/km) at 1.06μ. It was found that the optical losses exhibited by thallium halide single crystals in the CO laser emission range could be reduced effectively by multiple crystallization and zone purification of the original salt.