High-powered non-planar ring resonator mid-IR ZGP OPO, a parametric study

We report on a compact non-planar ring resonator optical parametric oscillator (OPO) based on ZnGeP 2 (ZGP) crystal and emitting in the 3–5 µm spectral region. We study the influence of parameters such as pump beam diameter, OPO cavity length, and crystal holder cooling on the output beam performance of the OPO using miniaturized versions of the non-planar ring resonators. We compare the performance of a linear cavity with two types of non-planar ring resonators, known as RISTRA and FIRE. The average output power at 10 kHz pulse repetition rate is up to 30.3 W from the RISTRA cavity and up to 26.7 W from the FIRE cavity. A miniaturized version of the FIRE cavity, with a shorter round-trip length, generates 23.8 W of average output power with a beam propagation factor of M 2 ∼ 2.5.