Chiral photochromic liquid crystalline polymers for holography applications

A series of novel chiral azodye homo- and copolymers has been investigated for applications in optical data processing and display technology. Supramolecular chirality in those systems due to helical superstructure leads to specific photo-optical response to circularly polarized light and, therefore, for creation of advanced photorecording media, especially for polarization holography. Highly twisted smectic-like mesophases of side chain homo- and copolymers (short pitch TGB A* phase) appear visually transparent and optically isotropic but possess a hidden liquid crystalline ordering, giving rise to rewriteable photorecording in relatively thick polymer films with high photoinduced phase retardation and diffraction efficiency. The amplitude gratings were written in polymer films with linearly polarized light but the phase gratings with circularly polarized light. Evolution of the photoinduced birefringence and diffraction efficiency, ill, is studied. For some polymers, polarization gratings are obtained with ill value above 30%; overmodulation effects of the grating recording are observed and discussed. The effect of dark self-amplification is reported.