Circularly polarized light generated by photoexcitation of luminophores inglassy liquid-crystal films

Optical information processing, display and storage can be accomplished wit h linearly or circularly polarized light, In passive (non-emitting) devices , linear polarization can be produced by anisotropic absorption of light(1) , whereas circular polarization has been attained by selective reflection o f unpolarized light propagating through a chiral-nematic liquid-crystal fil m(2). Active (light-emitting) devices capable of polarized emission are als o needed. In principle, optical and electronic excitation of materials cont aining uniaxially and helically arranged luminophores should produce linear ly and circularly polarized emission, respectively. In practice, the former is easier to achieve and is therefore more technologically advanced(3-8). Here rye report the generation of strongly circularly polarized photolumine scence from films of glass-forming chiral-nematic liquid crystals(9) in whi ch are embedded light-emitting dopants, This host material apparently induc ed alignment of the luminophores to a degree that produces almost pure circ ular polarization within the 400-420-nm wavelength band of the emitted ligh t. We anticipate that composite films of this sort might find applications within photonic technology such as colour-image projection(10) and stereosc opic displays(11).