Broadband carbon monoxide laser system operating in the wavelength range of 2.5 – 8.3 μm

A two-cascade frequency conversion of CO-laser radiation is demonstrated in a single sample of a nonlinear ZnGeP₂ crystal. The crystal is pumped by a repetitively pulsed cryogenic lowpressure CO laser operating on ~150 vibration – rotational transitions in the wavelength range 5.0 – 7.5 μm, which corresponds to the frequency range of a half octave. In the first conversion cascade, generation of second harmonic and sum frequencies of various pairs of CO-laser radiation give ~350 emission lines in the wavelength range 2.5 – 3.7 μm. In the second cascade, by mixing the radiation converted in the first cascade with the residual radiation of the CO laser we have obtained ~90 lines in the range 4.3 – 5.0 μm and more than 80 lines in the range 7.5 – 8.3 μm. Thus, using a single sample of the nonlinear ZnGeP₂ crystal pumped by the radiation of a single CO laser we have produced a source of broadband (more than one and a half octaves) laser radiation, simultaneously operating at ~670 lines in the wavelength range 2.5 – 8.3 μm.