3RD-ORDER OPTICAL NONLINEARITY OF C-60, C-70, AND CS2 IN BENZENE AT 1.06-MU-M

By measuring the third-order nonlinear optical susceptibility chi1111(3)(-omega,omega,omega,-omega) at 1.06 mum of various solutions of C60 and C70 in benzene, we place limits on the hyperpolarizabilities of these molecules of -180 less-than-or-equal-to (gamma1111C60/gamma1111benzene) less-than-or-equal-to 60 and -120 less-than-or-equal-to (gamma1111C70/gamma1111benzene) less-than-or-equal-to 250, respectively. These limits assume that 1.06 mum is near the long-wavelength limit where chi(3) must be real. We also give limits on the imaginary parts of the hyperpolarizabilities, making no assumptions about their phases. The magnitudes of these limits are two orders of magnitude smaller than several values that have been published. We checked our experimental technique by measuring the nonlinear susceptibility of CS2-benzene mixtures and found the value for chi(CS2)(3)/chi(benzene)(3) of 5.7 +/- 0.5. This agrees with parameters deduced from may different experiments published previously.