Advantages of Highly Ordered Polymer-Dyes for Lasing in Chiral Nematic Liquid Crystals

We have studied lasing in dye-doped chiral nematic liquid crystals (N*LCs). To demonstrate the advantages of using a polymer dye, that is highly aligned along the local director of N*LCs, over commercial small molecule dyes such as 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostryl)-4H-pyran (DCM), comparative studies of the fluorescence spectra, lasing conditions and order parameters have been made using polymer-dye doped N*LC and DCM-doped N*LC cells. Right- and left-circularly polarized fluorescence spectra for both dyes were accurately simulated by taking account of their density of modes and order parameters. These results indicate that the greater alignment afforded by the polymer dye in N*LCs provides ideal conditions for lasing.