Recent advances in nonlinear materials for 5-20 /spl mu/m wavelength generation

Summary form only given.Recent advances in infrared nonlinear materials have renewed interest in solid-state laser sources for generating radiation in the 5-12 /spl mu/m range. We list the properties of several commercially-available far-IR materials, as well as those of two new mixed crystals being developed for non-critically-phase-matched (NCPM) frequency conversion. Generating 8-12 /spl mu/m radiation directly from a 1 /spl mu/m Nd pump laser in a singie step requires nonlinear materials with the broadest transparency and phase-matching ranges. Only AgGaS/sub 2/ and GaSe meet these criteria, and both have significant limitations. AgGaS/sub 2/ has one of the lower nonlinear coefficients among these nonlinear optical materials, and beyond 10.5 /spl mu/m its performance is limited by the onset of multi-phonon absorption.