Efficient doubling and CW difference frequency mixing in the infrared using the chalcopyrite CdGeAs2

We have obtained fifteen percent average internal power conversion efficiency for second harmonic generation in CdGeAs₂ of radiation from a TEA CO₂ laser operating at 10.6 μm. This is the highest reported doubling efficiency for a CO₂ laser. We have also observed cw difference frequency mixing in CdGeAs₂ at wavelengths between 11.4 and 16.8 μm using grating-tuned CO and CO₂ lasers. The CdGeAs₂ crystals are significantly improved in size and optical quality over those previously available.