Thermal behavior of random lasing in dye doped nematic liquid crystals

The role of the thermally modulated order parameter in the diffusive laser action observed in dye doped nematic liquid crystals was investigated. Above a given pump energy a randomly distributed series of bright tiny spots appear, giving rise to a strongly fluctuating emission pattern. The spectral analysis reveals discrete sharp peaks (about 0.5 nm) slightly blueshifted with respect to the highest efficiency region of the gain medium. A comparative study was performed in systems having different sizes and confining geometries, corroborating the idea that the random lasing observed in dye doped nematic phase is fluctuation driven through a recurrent multiple scattering process. (c) 2006 American Institute of Physics.