.Optics Communications 155 1998 47–50 Two-photon absorption in GaSe and CdGeAs2

.We measured two-photon absorption TPA coefficients, at room temperature, for two noteworthy mid-infrared nonlinear-optical crystals, namely GaSe and CdGeAs in the wavelength range corresponding to E r2-"v-E. We used2 g g the nonlinear transmittance technique, employing different types of nano- and picosecond lasers with wavelengths ranging from 0.68 to 2.8 mm, and the dynamic range of laser intensities spanning 6 orders of magnitude. TPA coefficients were . y9 . . y7 found to be bs 6"1.2 =10 cmrW for GaSe at lf700 nm and bs 2.5"0.5 =10 cmrW for CdGeAs at