| Abstract: | We have obtained the complete polarization dependence of the two-photon absorption coefficient beta by measuring the orientational dependence and the contrast ratio of the photocurrent in an Al(0.2) Ga(0.8) As waveguide autocorrelator at an optical frequency far above the half-bandgap. The measured polarization dependence is consistent with theory and previous picosecond nonlinear transmission experiments. The cubic symmetry of the nonlinearity provides a contrast ratio that exceeds 2, which is larger than would be obtained assuming an isotropic medium and Kleinmann symmetry. This device was used to obtain an autocorrelation of a mode-locked Nd:YLF laser. |
