Continuous tunability and high efficiency are obtained from an intra-cavity double Optical Parametric Oscillator (OPO) pumped by a frequency-doubled diode-pumped Nd:YAG laser. The OPO is tunable from 760 - 1040 nm with 30% efficiency, giving 380 - 520 nm tunability after intra-cavity doubling with 40% efficiency.
Alex H. Kaz,
Larry R. Marshall,
"Continuously tunable diode-pumped UV-blue laser source", Proc. SPIE 1864, Solid State Lasers IV, (17 June 1993); doi: 10.1117/12.146875; https://doi.org/10.1117/12.146875