16 μm generation from phase-matched 4-wave mixing of CO₂ and NH₃ laser radiation in germanium

We report the generation of 16 µm radiation by nearly collinear phase-matched 4-wave mixing of CO₂ (10.7 µm) and NH₃ (12.8 µm) laser radiation in germanium. Measurements of the mixing efficiency at room temperature and at 77 K are compared with calculations. The potential mixing efficiency of the process is estimated, and techniques for obtaining completely continuous tuning near 16 µm are discussed. © 1978.