Random lasing in a dye doped cholesteric liquid crystal polymer solution

Random lasing in rhodamine 6G (R6G) doped ethyl-cryanoethyl cellulose [(E-CE)C]/acrylic acid (AA) cholesteric liquid crystal (LC) solution without scattering particles was studied. The effects of concentration of (E-CE)C/AA solution and the thickness of the sample on the random lasing were investigated. The random laser with coherent feedback occurs in (E-CE)C/AA anisotropic solution, while only amplified spontaneous emission (ASE) is observed in (E-CE)C/AA isotropic solution and AA solvent. The random laser also occurs in the (E-CE)C/poly(acrylic acid) (PAA)/R6G solid film with cholesteric structure through quick polymerization of AA. The experimental results suggest that the cholesteric LC domains play a very important role in this random lasing.