Alignment control method for liquid crystalline molecules and its application for an all-optical device

A nematic liquid crystalline monomer, containing photocrosslinkable divinyl and azobenzene moieties as functional groups was synthesized. Laser beam irradiation on a liquid crystalline cell of this material is capable of fabricating a very thin cross linked polymer layer on the alignment surface. The crosslinked polymer layer modifies the anchoring force between the alignment surface and liquid crystalline molecules. Meanwhile, the monomeric azobenzene moiety in the bulk interacts with incident light resulting in molecular reorientation through the trans-cis-trans-photoisomerization cycles. Combining the two characteristics mentioned above, a kind of optical device has been proposed. The driving mechanism of this device is the reversible phototriggered switching of the molecular orientation between the homogeneous and the homeotropic state.