  Because of the huge commercial importance of granular systems, the
second-most used material in industry after water, intersecting the industry in
multiple trades, like pharmacy and agriculture, fundamental research on
grain-like materials has received an increasing amount of attention in the last
decades. In photonics, the applications of granular materials have been only
marginally investigated. We report the first phase-diagram of a granular as
obtained by laser emission. The dynamics of vertically-oscillated granular in a
liquid solution in a three-dimensional container is investigated by employing
its random laser emission. The granular motion is function of the frequency and
amplitude of the mechanical solicitation, we show how the laser emission allows
to distinguish two phases in the granular and analyze its spectral
distribution. This constitutes a fundamental step in the field of granulars and
gives a clear evidence of the possible control on light-matter interaction
achievable in grain-like system.
