Abstract

The material TAS is a ternary chalcogenide salt with space group symmetry R3m, transparent between 1.3 and 17μm. Its large nonlinear optic coefficient and high damage threshold make TAS a promising candidate for nonlinear frequency conversion processes throughout the infrared.¹ Recently, large, good quality crystals of TAS have been grown, cut, polished, and coated for CO₂ laser second harmonic conversion by Westinghouse Research Laboratory. At NRL, a 2.5-cm diam 6-cm long crystal was pumped by a Lumonics 822 H P CO₂ laser operating on the 9-μm P(20) transition with energy of 350 mJ in a 100 ns FWHM pulse. In type I doubling conditions, we have observed up to 25% total energy conversion to the second harmonic at 1 J/cm² with no apparent crystal damage. Additionally, in a second similar TAS crystal we have observed both type I and type II sum frequency generation to the third harmonic with an overall total energy conversion of 1.5%. Progress toward a TAS-based OPO in the 8-12-μm range is also reported. (12min)

© 1986 Optical Society of America