Polarization independent liquid crystal gratings based on orthogonal photoalignments.

The polarization independence of liquid crystal gratings with alternate orthogonal aligned regions is theoritically studied and demonstrated by means of photoalignment technique. The different alignments in adjecent regions are achieved by two-step photo exposure to guide orientations of sulfonic azo dye layers and further align the liquid crystal molecules. Both one-dimensional and two-dimensional switchable phase gratings have been demonstrated. Such polarizer-free gratings show very high transmittance (∼92%), diffraction efficiency (over 31%), and optical contrast (over 150) including low power consumption. [ABSTRACT FROM AUTHOR]