Watt-level tunable deep ultraviolet light source by a KBBF prism-coupled device

We have obtained an average output power as much as 1.2 W at 200 nm by using a 2.71-mm thick KBe2BO3F2 crystal optically contacted by CaF2 and SiO2 prisms on the both sides. Watt-level average-power was generated tunably in the deep ultraviolet region from 185 nm to 200 nm. The average power is the highest, to our knowledge, ever obtained by nonlinear crystals in the wavelength region below 200 nm. (C) 2009 Optical Society of America