We used non-phase-matched second-harmonic generation (SHG) in the highly nonlinear but low-birefringence crystal SrB<sub>4</sub>O<sub>7</sub> for temporal characterization (autocorrelation) of femtosecond UV pulses to convert these pulses to wavelengths as low as 125 nm, close to the transparency limit of SrB<sub>4</sub>O<sub>7</sub>. The sensitivity of this method was ~1 J at the fundamental for a repetition rate of 1 kHz. We also used SHG at longer wavelengths to estimate the three nonlinear coefficients of SrB<sub>4</sub>O<sub>7</sub>.
© 2004 Optical Society of America
Valentin Petrov, Frank Noack, Dezhong Shen, Feng Pan, Guangqiu Shen, Xiaoqing Wang, Ryuichi Komatsu, and Volker Alex, "Application of the nonlinear crystal SrB4O7 for ultrafast diagnostics converting to wavelengths as short as 125 nm," Opt. Lett. 29, 373-375 (2004)