Generation of Pure Circularly Polarized Light Using Cholesteric Glassy Liquid Crystal (Ch-GLC) Films Doped with Dichroic Dyes*

Light absorption, emission, and propagation through structured media give rise to a myriad of fascinating optical phenomena, including the generation of various modes of light polarization in support of numerous photonic, medical, and optoelectronic technologies.  Natural light is largely unpolarized which can be considered to consists of equal amounts of right- and left-handed circularly polarized components. Of particular interest is the generation of pure circularly polarized light through monodomain Ch-GLC films. The underlying optical process is amenable to the analysis by Good-Karali theory for light absorption and reflection mediated by a dichroic dye oriented in the cholesteric film, resulting in a composite of selective absorption and reflection. This complex process culminates in preferential transmission and reflection of circularly polarized light of opposite handedness. A rich framework is identified for unravelling the effects on the transmission / reflection ratio by the Ch-GLC film thickness, the dichroic dye concentration, and spectral separation between the host film's stopband and the dye's absorption spectrum.