New materials for holographic data storage: molecular mechanisms and present limitations

Summary form only given. Photoaddressable polymers (PAP) are azobenzene containing liquid crystalline side chain polymers with two different functional groups attached to the polymer backbone: (1) Chromophores, mostly azobenzene or derivatives of azobenzene as antenna for the incident light and (2) mesogenic side groups. The function of the mesogenic side group is to follow the light-induced reorientation of the chromophores and to stabilize and amplify the new chromophore configuration (enhancement effect). PAP materials have received increasing attention during the last decade due to their intriguing properties and due to a broad range of potential applications especially in the field of optics and optoelectronics. Irradiation with polarized light results in an uniaxial orientation of the dye molecules: Light-induced isomerization cycles between the trans- and cis-configuration of the azo moiety lead to a reorientation of the transition dipole of the chromophore in a direction perpendicular to the polarization vector of the incoming light. The involved materials become birefringent with a light-induced optical axis parallel to the polarization direction of the incoming light. We present a new class of PAP with outstanding and new properties in terms of magnitude and stability of the light-induced birefringence.