Compact and Highly Efficient Passively Q−Switched Intracavity KTA-OPO at 1.53 and 3.47 µm

Both the signal (1.53 µm ) and idler (3.47 µm ) performances of a KTA−based optical parametric oscillator (OPO) are presented. The KTA-OPO is intracavity driven by a diode-pumped Nd:YVO₄/Cr:YAG passively Q−switched laser with a quite compact configuration. The signal and idler average output powers up to 941 and 583 mW, respectively, have been achieved, corresponding to an improved diode-to-idler conversion efficiency of 6.5% and a diode-to-OPO (signal+idler) conversion efficiency of 16.9%. At different pump levels, the signal pulse duration and repetition rate are detected to be in the range of 1.8–3.2 ns and 13–112 kHz, respectively. Moreover, near diffraction limited and Gaussian type beam profiles at 1.53 and 3.47 µm are also observed.