Generation of tunable 187.9–196-nm radiation in ?-Ba_2BO_4

Abstract
Tunable 187.9–196-nm vacuum-ultraviolet radiation was generated at room temperature in a beta barium borate crystal by sum-frequency mixing of Nd:YAG laser radiation and the second harmonic of a dye laser pumped by the second harmonic of the same Nd:YAG laser. By use of the advantageous noncollinear phase-matching configuration, a peak power of 1.3 kW was obtained at 194 nm with input power densities as low as 79MW/cm2 for 1064-nm and 0.65MW/cm2 for 237.3-nm radiation.