Sub-0.1 nm linewidth, >10 W mid-IR pulsed laser from a type-II ZGP OPO with intracavity silicon etalons

We report a narrow-linewidth, precisely tunable, high-power type-II ZGP OPO system pumped by a linewidth-narrowed Ho:YAG oscillator. Leveraging the narrow gain bandwidth of type-II ZGP and the high mode selectivity of silicon etalons, the system delivers 11.4 W at 3.09 μm with a linewidth of 0.07 nm (2.2 GHz) and 7.5 W at 6.46 μm with a linewidth of 1.7 nm. Insertion of the intracavity etalons compresses the signal linewidth by >10× without a significant power penalty. Precise temperature and angle control enable signal tuning from 3029 nm to 3170 nm (∼5 THz) with 0.5 GHz precision. This simple, cost-effective approach offers a powerful solution for narrow-linewidth mid-infrared sources.