Brillouin scattering
Brillouin scattering, named after Léon Brillouin, occurs when light, passing through a transparent medium interacts with that medium's periodic spatial & temporal variations producing that medium's refractive index.
Description
As described in optics, the index of refraction of a transparent material changes under deformation (compression-distension or shear-skewing).
The result of the interaction between the light-wave and the carrier-deformation wave is that a fraction of the transmitted light-wave changes its momentum (thus its frequency and energy) in preferential directions, as if by diffraction caused by an oscillating 3-dimensional diffraction grating.
If the medium is a solid crystal, a macromolecular chain condensate or a viscous liquid or gas, then the low frequency atomic-chain-deformation waves within the transmitting medium (not the transmitted electro-magnetic wave) in the carrier (represented as a quasiparticle) could be for example:
- Mass oscillation (acoustic) modes (called phonons);
- Charge displacement modes (in dielectrics, called polarons);
- Magnetic spin oscillation modes (in magnetic materials, called magnons).
See also
External links
- Brillouin scattering @ Wikipedia
