Photonic Band Gap Aspects of Liquid Crystals
Tuesday, October 26, 2004 - 9:30am - 10:20am
Liquid crystals with modulated ground states are periodic dielectric structures, and hence they are self-assembled photonic band gap materials. Fluorescent emission is suppressed in the stop band, but is enhanced at the band edges, and, above a pump threshold, distributed feedback lasing occurs. We interpret experimental observations of reflectance, fluorescence and lasing in terms of the density of states, and give a detailed description of this for helical cholesteric liquid crystals. Lasing is due to the singularity in the density of states at the band edges.