A tunable laser-based mid-infrared source for use in trace gas detection.

摘要

A new widely tunable mid-infrared (IR) source based on difference-frequency generation (DFG) in Gallium Selenide (GaSe) for use in high-resolution spectroscopy and trace gas detection is described. The characteristics of type-I phasematching in GaSe are studied. Preliminary results on the improvement of the dispersion relations for GaSe are presented. Spectroscopic feasibility experiments are reported that involve the spectroscopy of ethylene {dollar}rm (Csb2Hsb4){dollar} at low pressures near 950 {dollar}rm cmsp{lcub}-1{rcub}.{dollar} Two near-IR Ti:Sapphire lasers served as convenient pump sources, which can be eventually replaced by two high power near-IR diode lasers. Design issues (including optimum elliptical focusing conditions), potential improvements and new directions are also discussed.