title: Polarization-independent holographic gratings based on azo-dye-doped polymer-dispersed liquid-crystal films.
abstract: We demonstrate polarization-independent holographic gratings (PIHGs) based on azo-dye-doped polymer-dispersed liquid crystal films. The PIHGs are recorded by irradiation under an intensity-modulated interference field, generated by two linearly polarized green optical beams, and by simultaneously applying a suitable AC voltage to the sample. The photoexcited azo dyes are adsorbed onto the UV-cured polymer film with their long axes parallel to the normal of the substrate. When the applied voltage is switched off, the PIHGs are generated with periodic modulation of liquid-crystal structures with transparently homeotropic and randomly scattered alignments. Additionally, the generated PIHGs can be completely switched off by an applied voltage.
authors.affiliation: Department of Physics, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Andy Ying-Guey
authors.initials: AY
authors.lastname: Fuh
authors.forename: Che-Chang
authors.initials: CC
authors.lastname: Chen
authors.forename: Ko-Ting
authors.initials: KT
authors.lastname: Cheng
authors.forename: Cheng-Kai
authors.initials: CK
authors.lastname: Liu
authors.forename: Wei-Ko
authors.initials: WK
authors.lastname: Chen