Migration induced reorientation and anisotropic grating formation in photoreactive polymer liquid crystals

We have presented the results of some experimental studies aimed at quantifying the anisotropic holographic recordings in photoreactive polymer liquid crystals. In addition to the surface-relief gratings, index modulation gratings also appear during the holographic recording process, and the resulting dual gratings with strong anisotropy were characterized using the diffraction theory. The index modulation gratings showed strong optical anisotropy although the gratings were recorded by means of intensity holographic technique with only circularly polarized light. The experimental results including the induced birefringence were explained on the basis of the molecular migration.