title: Stimulated Rayleigh-Bragg scattering enhanced by two-photon excitation.
abstract: A frequency-unshifted and backward stimulated Rayleigh scattering can be produced in a linearly transparent but two-photon absorbing medium. Using a novel two-photon active dye solution as the nonlinear medium pumped by 532-nm and ~10-ns laser pulses, a highly directional backward stimulated scattering at the pump wavelength can be readily observed. The experimental results on spectral structure, spatial and temporal behaviors, and output/input relationship of this new type of stimulated scattering are presented. To explain the observed phenomenon and its experimental behaviors, a physical model of feedback mechanism provided by a two-photon-excitation enhanced Bragg grating inside the scattering medium is proposed. Comparing to other types of stimulated scattering, the stimulated Rayleigh-Bragg scattering exhibits the advantages of no-frequency shift, low threshold, and low requirement for pump spectral line-width.
authors.forename: Guang
authors.initials: G
authors.lastname: He
authors.forename: Tzu-Chau
authors.initials: TC
authors.lastname: Lin
authors.forename: Paras
authors.initials: P
authors.lastname: Prasad