In my last post I mentioned Raman scattering and by a bit of good fortune I now get to talk about its older brother Brillouin scattering. While Raman scattering is when light interacts with the vibrations in the bonds of molecules, Brillouin scattering is when light interacts with the vibrations in lattices often containing many particles. Raman is used for chemical composition while Brillouin is used for elasticity and optical properties. In fact Brillouin scattering is the reason light entering a medium changes speed and so refracts.
A scientific paper was recently published with its main focus being Brillouin scattering at very small scales. This can become quite complicated as vibrations in the material can change where the boundary is by a substantial amount and pressure can change the refractive index, normally just a small amount, but massive on such a small scale. By perfectly mirroring these two affects by manipulating qualities of the material being scattered through (a thin wire in the experiment) the scattering could be perfectly cancelled. Although it still needs to be upgraded to a large scale if it could be done it would be a material that didn’t refract light that passed through it and was perfectly without distortion.