Simulating effects of cavity detuning on temporal pulse walk-off in a mid-IR pulsed GaSe SPOPO

We present simulation cavity detuning and walk-off effects from a 5 𝑚𝑚 GaSe crystal in synchronously pumped singly resonant optical parametric oscillator (SPOPO) configuration. A pulsed mid-infrared external cavity quantum cascade lasers (ECQCL) at 8 𝜇𝑚 is used as a pump that produces a 9500 nm signal. The simulation is based on theoretical model using generalized Cheung–Liu master equation. The equation incorporates material dispersion, group-velocity dispersion (GVD), temporal walk-off, gain saturation, cavity detuning, and round-trip losses. For different pump strengths and cavity detuning, important metrics like threshold power, intracavity pulse shape, Root Mean Square (RMS) bandwidth, and signal conversion efficiency were carefully examined. The simulation reveals that the temporal pulse walk-off reduces peak power conversion efficiency, whereas cavity detuning can optimize signal bandwidth. The results provide guidance for experimental design of a Mid-IR SPOPO design operating in the 8–11 𝜇𝑚 range.