This experimental work is aimed to investigate the thermalbehavior of random laser action in dye doped nematic liquid crystals. Thestudy evidenced an important temperature dependence of the random lasingcharacteristics in the nematic phase and in close proximity of the nematici sotropic(N-I) phase transition. A lowering of the laser emission intensity asthe temperature increases is strictly related to the shift of the lasingthreshold as function of the temperature even though the pump energy iskept fixed. The optical losses increasing owing to the thermal fluctuationenhanced scattering drive the input-output smoother behavior until thesystem stops to lase, because below threshold. The unexpected reoccurrenceof random lasing at higher temperature, in proximity of N-I transition isfound to be related to a different scattering mechanism, the micro-dropletsnucleation and critical opalescence.
Thermo-recurrent nematic random laser
DE LUCA, Antonio;VERSACE, Consolato Carlo;STRANGI, Giuseppe
2009-01-01
Abstract
This experimental work is aimed to investigate the thermalbehavior of random laser action in dye doped nematic liquid crystals. Thestudy evidenced an important temperature dependence of the random lasingcharacteristics in the nematic phase and in close proximity of the nematici sotropic(N-I) phase transition. A lowering of the laser emission intensity asthe temperature increases is strictly related to the shift of the lasingthreshold as function of the temperature even though the pump energy iskept fixed. The optical losses increasing owing to the thermal fluctuationenhanced scattering drive the input-output smoother behavior until thesystem stops to lase, because below threshold. The unexpected reoccurrenceof random lasing at higher temperature, in proximity of N-I transition isfound to be related to a different scattering mechanism, the micro-dropletsnucleation and critical opalescence.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.