Difference-frequency generation in AgGaS2 by using single-mode diode-laser pump sources

Abstract

Recent advances in the development of high-power single-mode III-V diode laser technology now offer the possibility of using diode lasers as pump sources in difference frequency generation (DFG). Because of the compact size and direct electric excitation of diode lasers, a robust, portable diode laser based DFG spectrometer especially suitable for applications in environmental monitoring of trace species can be constructed. We report the mixing of a red single-mode III-V diode laser with a tunable single-frequency Ti:Sapphire laser in AgGaSs. For 1 W of Ti:Sapphire laser power and 12.1 mW of diode laser power up to 1.4 μW of cw tunable, infrared (λ5=μm), narrow band coherent radiation has been generated using Type I noncritical phase-matching. The applicability of this novel laser source to high resolution molecular spectroscopy has been demonstrated by obtaining a test spectrum. The effect of the non-Gaussian diode laser beam on the DFG conversion efficiency has been investigated. The feasibility of a compact, all-solid-state cw laser spectrometer based on the mixing of two diode lasers (808 and 690 nm) as pump sources in AgGaS2 has also been shown. With 12 mW of total diode laser input power more than 3 nW of infrared radiation could be generated to date. This research was supported by the Department of Energy, the Natural Science Foundation and the Robert A. Welch Foundation.