title: Biphotonic-induced reorientation inversion in azo-dye-doped liquid crystal films.
abstract: The reorientation inversion of liquid crystal molecules in azo-dye-doped liquid crystal (ADDLC) films irradiated by biphotonic (green and red light) lasers is studied using the self-phase-modulation method. The results show that the induced change of refractive index (∆n) in an ADDLC cell illuminated with a fixed intensity of green light increases with the red-light intensity. Notably, the value of ∆n is initially negative, and becomes positive when the intensity of the red laser is increasing. It is due to the fact that an extra positive torque is exerted on the LCs, which is produced by cis-isomers upon absorbing red light to compensate the negative torque induced by the excitation of the green light.
authors: Department of Electro-Optical Engineering, National Formosa University, Yunlin, Taiwan.
authors: Hui-Chi
authors: HC
authors: Lin
authors: Chia-Wei
authors: CW
authors: Chu
authors: Ming-Shian
authors: MS
authors: Li
authors: Andy Ying-Guey
authors: AY
authors: Fuh
mesh_terms: D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D050866:Liquid Crystals / Q000737:chemistry* / Q000528:radiation effects*; D008422:Materials Testing; D008567:Membranes, Artificial; D017785:Photons; D012031:Refractometry / Q000379:methods
chemical_list: D001391:Azo Compounds; D008567:Membranes, Artificial