Single-stage MHz mid-IR OPA using LiGaS₂and a fiber laser pump source

We present the design and characterization of a tunable mid-IR optical parametric amplifier (OPA) with a 1 MHz 1033 nm fiber laser pump source. The OPA generates >10 nJ/pulse tunable from 3-7.5 μm with 85-165 cm-1 bandwidth and 140-540 fs pulse durations. The design utilizes a single stage of collinear, Type I amplification in lithium gallium sulfide (LGS) seeded by the near-IR portion of a super-continuum (SC) generated in yttrium aluminum garnet (YAG). The resulting mid-IR idler beam is isolated as the output. This single-stage OPA is a simple and convenient source of high-repetition-rate, tunable mid-IR radiation for high-throughput ultrafast infrared spectroscopy.