Optical properties of holographically generated twisted nematic liquid-crystal gratings

Abstract

By use of a trans-cis photoisomerization process occurring in an azo-benzene side chain, various twisted nematic liquid-crystal (LC) gratings are fabricated in LC cells. Two counterpropagating orthogonally polarized beams produce a polarization modulation, which inscribes the replica polarization modulation inside LC cells holographically, providing twisted nematic LC gratings. Micro structure, diffraction properties, and electrooptic tunability of diffraction efficiency are examined experimentally. From the Fourier transformation of the Jones matrix of twisted nematic LC gratings, Stokes parameters of the zeroth and first diffraction orders are calculated and compared with the optical measurements, resulting in a good agreement. © 2008 Optical Society of America.