Diffraction characteristics of a liquid crystal polarization grating analyzed using the finite-difference time-domain method

This work studies the polarization characteristics of diffracted beams from a liquid crystal polarization grating. The grating is fabricated by exploiting the photo-alignment effect on a substrate that is coated with an azo dye-doped polyvinyl alcohol (PVA) film. The mechanism is induced by the irradiation of this film with suitably polarized light, which reorients the dyes. The reoriented dyes then align the liquid crystals (LCs). An LC polarization grating is fabricated using this approach. The LC alignment of the grating on one substrate is uni-directionally parallel to the surface, while that on the other is rotated. The polarization and the intensity of the diffracted beams are measured. A simulation based on the finite-difference time-domain (FDTD) method is performed and is very consistent with the experimental results. (C) 2007 Optical Society of America.