Second-Harmonic and Difference-Frequency Generation in Proustite

Abstract

Single crystal proustite was used for the second-harmonic generation (SHG) from the 9.3, 9.6 and 10.6μm lines of a cw CO₂ laser and for the difference-frequency mixing (DFM) of the 633 nm line of a He-Ne laser and the 9.3 or 9.6 μm line of a cw CO₂ laser. Type 1 phase matching was used, with the crystal cut and polished so that signal and pump propagated as ordinary and extraordinary waves, respectively in a XY plane of the crystal. Measured values of internal phase-matching angles for SHG and DFM are in good agreement with theory and that of the effective nonlinear coefficient was (2-5) ×10^-8 esu.