Polarization Holographic Device Using Photoreactive Polymer Liquid Crystals

Optical phase gratings were fabricated from photo-crosslinkable polymer liquid crystals with mesogenic 4-(4-methoxycinnamoyloxy)biphenyl side groups by irradiating with 325 nm interference lights and subsequent annealing at elevated temperatures. Recorded phase gratings were verified after the annealing process, although no gratings were observed immediately after the exposure. The characteristics of the phase gratings were strongly dependent on the polarization states of the two recording beams, and the resultant gratings involve not only linear birefringence caused by the reorientation of the mesogenic groups but also surface relief modulation generated by the molecular migration.