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 i rradiation on a liquid crystalline cell of this material is capable of fabr icating a very thin cross linked polymer layer on the alignment surface. Th e crosslinked polymer layer modifies the anchoring force between the alignm ent surface and liquid crystalline molecules. Meanwhile, the monomeric azob enzene moiety in the bulk interacts with incident light resulting in molecu lar reorientation through the trans-cis-trans-photoisomerization cycles. Co mbining the two characteristics mentioned above, a kind of optical device h as been proposed. The driving mechanism of this device is the reversible ph ototriggered switching of the molecular orientation between the homogeneous and the homeotropic state. (C) 2000 American Institute of Physics. [S0003- 6951(00)04027-4].