1.5 µm pulse-train self-optical parametric oscillator with tunable output based on an Nd:MgO:PPLN crystal

This study demonstrates a 1.5 μm pulse-train self-optical parametric oscillator based on an Nd:MgO:PPLN crystal. A dynamical model is established to describe the self-optical parametric oscillation process, enabling analysis of the population inversion density together with the photon densities of the fundamental, signal, and idler waves. The results demonstrate that the subpulse number and subpulse interval can be precisely regulated by adjusting the pump repetition frequency, duty cycle, and Q-switching repetition frequency. Moreover, the pulse-train envelope can be shaped by tailoring the pump waveform to modulate the subpulse amplitude. Good consistency is observed between the theoretical results and experimental measurements. With a pump power of 40 W, the 1.5 μm pulse-train delivers a minimum subpulse width of 20.4 ns and a maximum average output power of 1.66 W, corresponding to a slope efficiency of 5.4%. This work provides an effective approach for flexible modulation of 1.5 μm pulse-train sources, offering a theoretical basis for compact 1.5 μm pulse-train lasers.