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 th ese molecules of -180 less-than-or-equal-to (gamma1111C60/gamma1111ben zene) less-than-or-equal-to 60 and -120 less-than-or-equal-to (gamma11 11C70/gamma1111benzene) less-than-or-equal-to 250, respectively. These limits assume that 1.06 mum is near the long-wavelength limit where c hi(3) must be real. We also give limits on the imaginary parts of the hyperpolarizabilities, making no assumptions about their phases. The m agnitudes of these limits are two orders of magnitude smaller than sev eral values that have been published. We checked our experimental tech nique by measuring the nonlinear susceptibility of CS2-benzene mixture s 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 pub lished previously.