Programmable sub-pulse control and LSTM-PINN prediction in a mid-infrared SOPO

Programmable generation of mid-infrared pulse bursts with tailored sub-pulse features remains a critical challenge. Here, we demonstrate a 3.8 μm self-optical parametric oscillator based on an Nd:MgO:PPLN crystal that enables independent control of sub-pulse number, spacing, and amplitude via dynamic stepwise Q-switching. At 10 kHz, the system delivers typical sub-pulse energy of 77.3 μJ, with a minimum width of 23.5 ns and interval of 150 ns. Furthermore, a physics-informed LSTM-PINN framework accurately predicts pulse width, amplitude, and energy (R² = 0.99 and 0.93 for training and validation), simplifying experimentation and modeling while paving the way for intelligent laser control.