Three-stage frequency conversion of sub-microsecond multiline CO laser pulse in a single ZnGeP₂ crystal

Broadband three-stage frequency conversion of multiline sub-microsecond CO laser radiation in a single sample of ZnGeP₂ crystal was experimentally and numerically studied for the first time, to the best of our knowledge. As a result, the hybrid laser system emitted more than 200 narrow spectral lines within the 2.4-6.2 μm spectral range. The measured conversion efficiencies of the first, second, and third stages were about 4.8%, 0.4%, and 0.05%, respectively. Our numerical simulation demonstrated that the third stage of this frequency conversion can extend the laser system spectrum toward the shorter wavelength of 2.2 μm.