Frequency Down-Conversion of 1 µm Laser Radiation to the Mid-IR using Non-Oxide Nonlinear Crystals in Cascaded Intracavity Configurations

Optical parametric oscillators (OPOs) based on AgGaSe2 and BaGa2GeSe6, and difference-frequency generation (DFG) in AgGaSe2 and BaGa4Se7 are studied inside the cavity of an oxide-crystal-based OPO to produce widely-tunable mid-IR radiation in the 4.4−18-µm range.