Abstract

The generation of 3–5 μm mid-infrared laser radiation by using a AgGaSe₂ nonlinear crystal has been attracting considerable attention as a compact coherent light source for laser radar. There have been some reports on the frequency doubling of a gain-switched spike-mode TEA–CO₂ laser with AgGaSe₂ crystal, but the energy-conversion efficiency obtained was less than 30%.^1,2 This paper describes efficient second-harmonic generation of a TEA–CO₂ laser with a multipass pumping scheme in a small AgGaSe₂ bulk crystal. A high energy conversion efficiency of 35% was obtained when the fundamental beam was transmitted into the crystal with a Z-fold optical configuration.

© 1995 Optical Society of America