title: Enhanced diffraction properties of photoinduced gratings in nematic liquid crystals doped with Disperse Red 1.
abstract: Diffraction properties of photoinduced gratings recorded by overlapping two coherent beams at 532 nm in nematic liquid crystals doped with Disperse Red 1 were investigated with a probe beam at 632.8 nm. The grating was formed due to the alignment of dye molecules that leaded to the reorientation of the liquid crystal phase. The diffraction efficiency of the photoinduced grating was found to increase rapidly when the sample temperature was close to the clearing point in the nematic phase and a nearly 30-fold enhancement of the first-order diffraction efficiency was obtained. The pretransitional enhancement of the diffraction efficiency was discussed in terms of the reorientation of liquid crystals, optical nonlinearity effects and the onset of critical opalescence near the nematic-isotropic phase transition. Moreover, a peak shift of diffraction efficiency towards the lower temperature was observed with the increase of recording light intensity, which was attributed to laser induced photochemical disordering.
authors.affiliation: State Key Lab of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University.
authors.forename: Hongjing
authors.initials: H
authors.lastname: Li
authors.forename: Jianhao
authors.initials: J
authors.lastname: Wang
authors.forename: Changshun
authors.initials: C
authors.lastname: Wang
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zeng
authors.forename: Yujia
authors.initials: Y
authors.lastname: Pan
authors.forename: Yifei
authors.initials: Y
authors.lastname: Yang
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D003460:Crystallization; D008027:Light; D050866:Liquid Crystals / Q000737:chemistry*; D055095:Optics and Photonics; D013057:Spectrum Analysis; D013696:Temperature; D013997:Time Factors
chemical_list: D001391:Azo Compounds; C069318:Disperse Red 1