Effect of thick anisotropic NLC layer on lasing in polymeric cholesteric liquid crystals.

We have studied the lasing characteristics from a dye-doped nematic liq. crystal layer sandwiched by two polymeric cholesteric liq. crystal films as photonic band gap materials. The nematic layer possessing birefringence brings about the following remarkable optical characteristics: (1) reflectance in the photonic band-gap (PEG) region exceeds 50 %, due to the retardation effect, being unpredictable from a single CLC film; (2) efficient lasing occurs at the notch of PEG; (3) the lasing emissions contain both right- and left-circular polarizations. In this study, we demonstrate that a 100-$μ$m-thick nematic liq. crystal layer system shows several dips, resulting in multi-mode lasing actions just at the dips within PBG. [on SciFinder(R)]