POLARIZED HYPER-RAYLEIGH LIGHT-SCATTERING MEASUREMENTS OF NONLINEAR-OPTICAL CHROMOPHORES

Hyper-Rayleigh light scattering measurements at incident wavelengths o f 1064 and 1319 nm are reported for several organic nonlinear optical chromophores in solution with approximately 5%-10% uncertainty in the relative first hyperpolarizabilities. The measured chromophores includ e representatives from C-1, C-s, C-2V, and D-3 molecular point groups and include both neutral and ionic compounds. The measurements were ma de with 2-5 cm(-1) spectral resolution and include polarization analys is of the incident and scattered light. Polarization ratios were measu red with 2%-3% uncertainty for each molecule, and relative magnitudes of the hyperpolarizability components were deduced. Two-photon induced fluorescence from several chromophores was observed to overlap with t he scattered second harmonic light spectrum. The use of a scanning mon ochromator, however, generally allows the separation of these two sour ces of photons. The measured first hyperpolarizabilities are consisten t with previous electric field induced second harmonic generation meas urements of the same compounds, provided that the standard reference v alue for the nonlinear susceptibility of quartz is tab-Pn to be d(11)= 0.30+/-0.02 pm/V at 1064 nm. (C) 1996 American Institute of Physics.