MECHANICAL DEFORMATION OF A LIQUID-CRYSTAL DIFFRACTION GRATING IN AN ELASTIC POLYMER

We demonstrate the tuning of the diffraction efficiency in a polymer-d ispersed liquid crystal (PDLC) diffraction grating by mechanical shear deformation. We chose a photocurable thermoset with elastic mechanica l properties as the host material to demonstrate the tuning effect. Ra man-Nath gratings were prepared by anisotropically curing a mixture of commercial photopolymer doped with Liquid crystal. The mixture was co ntained between glass slides which were mounted in a simple shearing d evice. During the photopolymerization, the liquid crystal phase separa ted into 2-mu m droplets organized into channels with 3.8-mu m spacing . Gratings were deformed by shearing the samples in a direction perpen dicular to the channel orientation. The diffraction intensity and morp hology were monitored as a function of shear strain. Reversible tuning was observed due to the elastic nature of the matrix. (C) 1998 John W iley & Sons, Inc.