Modulation of output power and repetition rate in 1.5 μm passively Q-switched self-optical parametric oscillator by pulsed pumping

A compact 1.5 μm self-optical parametric oscillator (SOPO) was proposed, which utilized a pulsed laser diode (LD) to pump Nd:MgO:PPLN crystals. The rate equation of pulsed-pumped 1.5 μm passively Q-switched SOPO was established. The variations in pulse width and repetition rate were simulated under different initial transmittances and duty cycles. In the experiment, the output power and repetition rate were modulated by adjusting the timing of the pulse pump and replacing Cr⁴⁺:YAG with different initial transmittance. Finally, with a modulation duty cycle of 30 % and setting the Cr⁴⁺:YAG initial transmittance to 93 %, we achieved an average output power of 2.60 W, a repetition rate at 26.14 kHz, and a single pulse width of 14.97 ns for the 1512 nm signal light, with an optical-to-optical conversion efficiency of 7.2 %, the beam quality factor was $M_x^2$ = 2.82, $M_y^2=2.67$. The experimental results demonstrated that the integration of pulse pumping technology with passive Q-switching not only ensured laser compactness but also enabled power and repetition rate modulation, ultimately realizing a miniaturized 1.5 μm SOPO with high power and high repetition rate characteristics.