SPECTRAL CONTENT AND DISPERSION OF HYPER-RAYLEIGH SCATTERING

We have used a high-intensity tunable picosecond infrared laser source to measure the spectral content of light scattered near the second ha rmonic for two well-known organic dyes, p-Nitroaniline and Disperse Re d 1, at a number of wavelengths in the near infrared. We found that in Disperse red 1 a broad two-photon fluorescence competes with the shar p hyper-Rayleigh peak. Further, dephasing of the virtual excited state leads to elimination of hyper-Rayleigh scattering in favor of fluores cence if the harmonic is in the linear absorption tail. We determined the dispersion of the magnitude of the first hyperpolarizability for b oth dyes, using a simple referencing technique, and found it to be con sistent with that of a two-level dispersion model. (C) 1996 Optical So ciety of America