  Propagation of light in a highly scattering medium is among the most
fascinating optical effect that everyone experiences on an everyday basis and
possesses a number of fundamental problems which have yet to be solved.
Conventional wisdom suggests that non-linear effects do not play a significant
role because the diffusive nature of scattering acts to spread the intensity,
dramatically weakening these effects. We demonstrate the first experimental
evidence of lasing on a Raman transition in a bulk three-dimensional random
media. From a practical standpoint, Raman transitions allow for spectroscopic
analysis of the chemical makeup of the sample. A random Raman laser could serve
as a bright Raman source allowing for remote, chemically specific,
identification of powders and aerosols. Fundamentally, the first demonstration
of this new light source opens up an entire new field of study into non-linear
light propagation in turbid media, with the most notable application related to
non-invasive biomedical imaging.
