COHERENT BACKSCATTERING OF OPTICAL 2ND-HARMONIC GENERATION IN SILVER FILMS

We report an experimental study of coherent scattering of optical seco nd-harmonic generation (SHG) due to excitation of the long-range surfa ce-plasmon mode at the interface between a thin silver film and a nonl inear quartz crystal. Fitting of the angular half-width of the SHG bac kscattering cone to a scattering model leads to a determination of the mean scattering displacement vector in the interface. Results from a study of the peak intensity and angular width of the backscattering co ne as a function of silver film thickness are given. A peak in the sca ttered SHG in the direction normal to the interface is also reported. Explanation of many of the observations reported here awaits a quantit ative theory of coherent backscattering of SHG with surface waves.