Comparative study of high-power CdSiP₂ OPO pumped by an ns-pulsed Ho:LLF laser at 2.06 µm versus the ZnGeP₂ crystal

We present a study of optical parametric oscillators using CdSiP₂ (CSP) and ZnGeP₂ (ZGP) crystals pumped by a nanosecond Q-switched 2.06 µm Ho:LiLuF₄ (Ho:LLF) laser in a compact linear cavity. In the Type I critical phase-matching configuration, we achieved an average output power of more than 8 W in the mid-IR band with good beam quality from the CSP OPO. The idler and signal waves can be tuned in a wide range of 3.2 - 5.2 µm by crystal rotation. The performance in terms of beam quality, pulse dynamics, and spectral response was compared to the ZGP OPO with the same crystal length of 9 mm.