Seeded optical parametric generator based on OP-GaAs for mid-wave and long-wave infrared beam generation

We propose and theoretically analyze a novel device with a simple architecture for high power mid-wave and long-wave infrared beam generation by employing a realistic model that takes the diffraction of the beams into account. The device is a seeded optical parametric generator (OPG) based on an aperiodic orientation-patterned GaAs (OP-GaAs) grating in which two optical parametric amplification (OPA) processes, OPA1 and OPA2, are simultaneously quasi-phase-matched along the full length of the crystal.

When pumped by a high-repetition-rate nanosecond-pulsed pump laser operating at 2.1 mu m and a low-power continuous-wave seed source at a wavelength of 2.74 mu m (signal), OPA1 in this crystal generates a long-wave infrared beam output at a wavelength of 8.8 mu m (idler) whose power conversion efficiency is enhanced by means of OPA2 compared to what is achievable with a single OPA process. OPA2 occurs as signal photons are down-converted to idler photons and difference-frequency (DF) photons at a wavelength of 3.98 mu m. These wavelengths have important applications in the fields such as infrared laser projector technologies, countermeasures against heat seeking missiles, remote sensing, and spectroscopy.