A simple ring cavity consisting of mirrors reflecting at the second harmonic is used to generate the fourth harmonic of low-power <i>Q</i>-switched Nd:YAG laser pulses. A large beam waist of 1 mm minimized the effects of double refraction and thermal loading of the nonlinear crystals. By simulating the low-power pulses with a small portion of the output from a 30-Hz flash-lamp-pumped <i>Q</i>-switched Nd:YAG laser, we obtained IR–UV energy conversion as great as 39.5% to yield 84-mW average power at 266 nm from 213 mW of single-mode 1064-nm radiation.
© 1997 Optical Society of America
Joachim Knittel and A. H. Kung, "39.5% conversion of low-power Q-switched Nd:YAG laser radiation to 266 nm by use of a resonant ring cavity," Opt. Lett. 22, 366-368 (1997)