IR spectrometer based on upconversion with intracavity nonlinear frequency converter

Abstract

The authors investigate the operation of a nonlinear IR spectrometer in which the probing IR radiation is obtained by frequency mixing the radiation of a pump laser with the radiation of a visible tunable dye laser. In so doing the generation of the difference frequency radiation and subsequent upconversion are realized using an intracavity method in the same nonlinear crystal. The spectral information is extracted by analyzing the dye laser radiation. The dye laser and pump laser radiation are combined with the help of a polarization prism or a selective mirror in the nonlinear crystal. Results for increases in spectral density are assessed.