Liquid crystal infiltrated random media: From the optical NTC-resistor to temperature tunable random lasers

Diederik S. Wiersma (1), Stefano Cavalieri (1), Marcello Colocci (1), Roberto Righini (1) and Fouad Aliev (2)

(1) European Laboratory for Non-linear Spectroscopy and INFM
Via Nello Carrara
1 50019 Sesto-Fiorentino Florence

(2) Dept. of Physics
University of Puerto Rico
San Juan
Puerto Rico

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).]