We will discuss experiments on various disordered dielectric systems
that are infiltrated with liquid crystals. An example of such a
material is liquid crystal infiltrated macro porous glass. The
diffusion of light in such a system depends strongly on temperature,
which allows to tune the diffusion constant of a single sample. This
is a new feature in multiple light scattering studies and opens up
interesting possibilities. For instance, it allows to create a random
laser with a laser threshold that depends on temperature. This tunable
random laser was realized by introducing optical amplification in a
liquid crystal infiltrated sintered glass. It represents a new type of
light source with an emission spectrum that can be controlled via
environment temperature and switched via an external electric
field. [See also: Wiersma et al., Nature 414, 708 (2001).]