Tunable ultraviolet radiation in the 200–230-nm region has been generated with beta barium borate crystals by type I sum-frequency mixing of the second harmonic with the fundamental beam from 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 efficiency of 21% at 208.3 nm with input power densities as low as 28 MW/cm<sup>2</sup> for the fundamental and 2.4 MW/cm<sup>2</sup> for its second-harmonic radiation. The absorption characteristic of a standard DNA sample has been studied with the generated tunable ultraviolet source, revealing additional features compared with those obtained with a spectrophotometer.
© 1998 Optical Society of America
Gopal C. Bhar, Pathik Kumbhakar, Udit Chatterjee, Abani Mohan Rudra, Yasuhiko Kuwano, and Hikaru Kouta, "Efficient Generation of 200–230-nm Radiation in Beta Barium Borate by Noncollinear Sum-Frequency Mixing," Appl. Opt. 37, 7827-7831 (1998)