2ND-ORDER NONLINEAR OPTICS IN ISOTROPIC LIQUIDS - HYPER-RAYLEIGH SCATTERING IN SOLUTION

The incoherent second-order nonlinear light scattering in a macroscopi cally isotropic molecular liquid has emerged as a simple and widely ap plicable technique for the experimental determination of the first hyp erpolarizability of nonlinear optical molecules in solution. The techn ique has become widely known as hyper-Rayleigh scattering. Until recen tly, electric-field-induced second-harmonic generation was the only so lution technique to determine molecular hyperpolarizabilities. Apart f rom being more complex a technique, the applied field also limits its applicability to neutral and dipolar solutions. In this paper, we pres ent the specific advantages of the new hyper-Rayleigh scattering techn ique and exemplify its wider scope with results from three different k inds of molecular materials: octopoles, biological chromophores, and q uantum colloids.