A Low-Pump-Threshold High-Repetition-Rate Intracavity Optical Parametric Generator Based on Periodically Poled Lithium Niobate

A low-pump-threshold high-repetition-rate intracavity optical parametric generator (IOPG) by using a periodically poled lithium niobate (PPLN) is reported. The PPLN, which is 18.7 mm long and has a grating period of 28.93 μm at room temperature, is inserted in a diode-end-pumped Nd:YVO4 laser with an acousto-optic Q switch. The parametric generation threshold is 1.3 W (diode laser power) at a Q-switch repetition rate of 19 kHz. At an incident diode pump power of 5 W, an average signal output power of 280 mW has been achieved. The signal pulse duration is approximately 85 ns. By changing the crystal temperature from 120°C to 250°C, the signal wavelength can be tuned from 1.493 μm to 1.538 μm.