Tunable coherent infrared source from 5-16 µm based on difference-frequency mixing in an indium-doped GaSe crystal

A tunable coherent infrared source based on a double-difference-frequency-mixing technique in an indium-doped GaSe crystal in the last stage, with a Nd:YAG laser as the basic pump source, is reported. Angular acceptance as well as spectral acceptance has been measured. The energy output of the infrared radiation has been measured. Absorption characteristics of polystyrene and polythene sheets have been measured with the generated radiation; the main peaks correspond to spectrophotometric measurement.