Compact low threshold Cr:YAG passively Q-switched intracavity optical parametric oscillator

We report a compact KTP-based intracavity optical parametric oscillator (IOPO) driven by a diode-end-pumped passively Q-switched Nd:YVO4/Cr:YAG laser. For the first time, we take the thermal lens effect of the Cr:YAG into consideration and discuss its impact on the signal output. Diode pump threshold as low as 0.52 W has been achieved, which is the lowest result reported to date. At the incident diode pump power of 4 W, we obtained the maximum signal average and peak power of 358 mW and 12.5 kW, respectively, corresponding to a diode-to-signal conversion efficiency of 9%. Moreover, cavity-dumping characteristic and pulse transforming process from 1064 to 1573 nm are qualitatively analyzed.