Efficient difference-frequency generation of 7–20-µm radiation in CdGeAs 2

Continuously tunable 6.8–20.1-µm mid-infrared radiation has been achieved by the use of frequency generation in CdGeAs2.?The signal and the idler output of an Er-laser-pumped ZnGeP2 optical parametric generator was used as the pump. The maximum external conversion efficiency reached 20%.