EFFICIENT GENERATION OF 200-230-NM RADIATION IN BETA-BARIUM BORATE BYNONCOLLINEAR SUM-FREQUENCY MIXING

Tunable ultraviolet radiation in the 200-230-nm region has been genera ted with beta barium berate crystals by type I sum-frequency mixing of the second harmonic with the fundamental beam hom a dye laser pumped by the second harmonic of the same Nd:YAG laser. A noncollinear phase- matching configuration has made it possible to realize conversion effi ciency of 21% at 208.3 on with input power densities as low as 28 MW/c m(2) for the fundamental and 2.4 MW/cm(2) for its second-harmonic radi ation. The absorption characteristic of a standard DNA sample has been studied with the generated tunable ultraviolet source, revealing addi tional features compared with those obtained with a spectrophotometer. (C) 1998 Optical Society of America. OCIS codes: 190.0190, 190.2620.