Abstract
Highly directional backward stimulated scattering has been observed from large-size-gold nanorods suspended in water, pumped with 816 nm and 10 ns laser pulses. In comparison with other known stimulated scattering effects, the newly observed effect exhibits the following features. (i) The scattering centers are impurity particles with a size comparable in order of magnitude to the incident wavelength. (ii) There is no frequency shift between the pump wavelength and the stimulated scattering wavelength. (iii) The pump threshold can be significantly lower than that of stimulated Brillouin scattering in pure water. The nonfrequency shift can be explained by the formation of a standing-wave Bragg grating induced by the interference between the forward pump beam and the backward Mie-scattering beam. The low pump threshold results from stronger initial Mie-scattering (seed) signals and the intensity-dependent refractive-index change of the scattering medium enhanced by metallic nanoparticles.
4 More- Received 4 January 2011
DOI:https://doi.org/10.1103/PhysRevA.85.043839
©2012 American Physical Society