Fiberpaedia
N
Nonlinear scattering
This is usually associated with an interaction of the light with vibrational energy in the molecular lattice, where light is scattered at a slightly different frequency to that of the incident light. Specifically Brillouin scattering and Raman scattering are mechanisms where photons (optical energy) either create or annihilate a phonon (vibrational energy) to change the optical frequency of the photon.