Effects of phase shift between two photo-alignment substrates on diffraction properties in liquid crystalline grating cells.

Diffractive optical devices using low-molar-mass liquid crystals are of great important for realizing numerical optical functions such as optical memory and information systems. In the present study the liquid crystalline gratings have been fabricated using a pair of photo-alignment substrates, and effects of the phase shift between the two photo-alignment substrates on the diffraction properties have been investigated. The liquid crystalline grating has been constructed with variable polarization dependence that can be controlled by the phase shift between the two photo-alignment substrates and twisted angles of the nematic directors. The theoretical considerations were also performed using the elastic continuum theory, Jones calculus, and diffraction theory. A guiding principle that controls the diffraction properties of the liquid crystalline grating cell was successfully presented.