Characterization of ZnGeP2 for parametric generation with near-infrared femtosecond pumping

Values for the nonlinear refractive index (n(2) approximate to 5.4 X 10(.5) cm(2)/GW) are reported as well as the two-photon absorption coefficient (b eta approximate to 0.25 cm/GW) in ZnGeP02 at wavelengths near half the band edge of this semiconductor nonlinear optical crystal. The Z-scan measureme nts were performed with a mode-locked femtosecond Cr:forsterite laser at 1. 26 mum and 83 MHz, and the nonlinear transmission measurements were accompl ished by a near infrared traveling wave optical parametric generator provid ing powerful femtosecond pulses at 1 kHz. In both cases, ZnGeP2 samples wit h reduced anomalous absorption were used. The parametric fluorescence in th ese 2-mm thin ZnGeP2 samples was studied with near infrared pumping and the optimum pump wavelength established lies between 1.9 and 2.1 mum. The femt osecond signal and idler pulses generated could be tuned between 2.5 and 12 mum at a maximum single pass internal conversion efficiency of 2.5%.