Compact Nd:YAlO $_{3}$ /RbTiOPO $_{4}$ Based Intra-Cavity Optical Parametric Oscillator Emit at 1.65

An intra-cavity optical parametric oscillator based on RbTiOPO₄ (RTP) crystal simultaneous output eye-safe light and mid-infrared wavelength light was demonstrated. An laser diode end pumped acousto-optic Q-switched Nd:YAlO₃ laser at 1.08 μm was used as the pump source. At an incident pump power of 8.7 W and a pulse repetition frequency of 20 kHz, total average output power up to 1.12 W (890 mW of signal light at 1.65 μm with and 230 mW of idler light at 3.13 μm) was obtained, with the diode to OPO total output conversion efficiency of 12.9%. The pulse width is about 4.5 ns and spectral linewidth is about 0.5 nm for the signal light. Compare to noncritical phase matching optical parametric oscillator using its isomorph KTP crystal, RTP crystal can extend signal wavelength up to 1.65 μm and absorb less idler wavelength.