MEASUREMENTS OF THE TENSOR PROPERTIES OF 3RD-ORDER NONLINEARITIES IN WIDE-GAP SEMICONDUCTORS

We extend the z-scan technique to provide for measurements of the sign and the magnitude of all the independent components of chi((3)) for i sotropic and cubic-symmetry materials. This technique is used to measu re the dispersion of the tenser components of the real and the imagina ry parts of chi((3)) for various wide-gap semiconductor materials by u se of femtosecond laser pulses. Our measurements of the polarization d ichroism of the nonlinear-index and two-photon absorption coefficients are in fair agreement with recent theoretical calculations; however, substantial discrepancies exist between the measured and predicted val ues for the corresponding anisotropy parameters.