Abstract

We have produced picosecond pulses of IR radiation tunable from 3.5 to 7.25 μm by difference frequency mixing in AgGaS₂. In contrast to IR sources based on mixing in LiNbO₃ and LilO₃,^1,2 mixing in AgGaS₂ allows tuning to >5 μm and, therefore, makes possible studies of a wider range of molecular vibrations and of narrow band gap semiconductors. In contrast to recent work using AgGaS₂ but based on amplified Nd:YAG/glass laser systems,³ our source is based on a cw mode- locked Nd:YAG laser at high repetition rate (76 MHz) and is, therefore, brighter and compatible with low-signal lock-in detection and signal averaging schemes. Because of the short time duration of these IR pulses, this source can be used for time-resolved studies, such as the observation of transient chemical species and carrier–carrier interactions in semiconductors.

© 1988 Optical Society of America