High efficiency KTiOAsO4 optical parametric oscillator within a diode-side-pumped two-rod Nd:YAG laser

A high efficiency KTiOAsO4(KTA) intracavity optical parametric oscillator (IOPO) is demonstrated within a diode-side-pumped acousto-optically (AO) Q-switched two-rod Nd:YAG laser. With a 25-mm-long X-cut KTA crystal, efficient parametric conversions to signal (1.54 mu m) and idler (3.47 mu m) waves are realized. The highest output power of 15.8 W including 12.7 W signal and 3.1 W idler power is obtained at a repetition rate of 7.5 kHz and a pump power of 208 W, corresponding to an optical-to-optical conversion efficiency of up to 7.6%. The signal pulse duration is 32 ns with a peak power of 53 kW. At a repetition rate of 12.5 kHz and the pump power of 208 W, the highest idler power of 3.4 W is obtained with a peak power of 14 kW and a pulse duration of 19 ns. And the beam quality factors (M (2)) of the signal and idler waves are determined to be around 2 and 20, respectively.