Photoaddressable Polymers for Optical Data Storage

Abstract

Photoaddressable polymers (PAPs) are side‐chain copolymer systems functionalized with azobenzene chromophores and mesogenic side groups. They show very large birefringence values after illumination with polarized light. The molecular mechanisms involved are photoinduced isomerization cycles of the azo side groups, which induce strong molecular reorientations (cooperative motion of light‐absorbing azobenzene chromophores and non‐absorbing mesogenic groups). Due to the long‐term and high‐temperature stability of their light‐induced birefringence, PAPs are very promising recording materials for optical data storage applications such as high‐capacity DVDs and holographic memory.

Shape‐Switchable Azo‐Macrocycles

“…Therefore they are preferred in photo responsive devices where stability is necessary. [15][48] [65]- [67] If a complex substitution pattern is considered for such devices, care should be taken to find compounds with a distinct and characteristic nin the absorption spectrum.…”

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

“…193 Moreover, the change in the alignment of these chromophores upon irradiation is investigated for the preparation of materials for optical data storage. [211][212][213] Finally, the bending of the molecule can be used to induce shape changes in nematic liquid-crystal elastomers which represents a fascinating example for the alteration of macroscopic changes in a material controlled on a molecular level. 206 Ionization reactions.…”

Azobenzene Polymers for Photonic Applications

“…Birefringence is the anisotropy in refractive index: Dn=n x À n y . Photoalignment in azobenzene systems can achieve extremely high values of Dn, up to 0.3-0.5 at B633 nm (Hagen and Bieringer, 2001;. Importantly, very high birefringence values can be obtained far outside of the azo-absorption band, which means that the birefringence can be utilized/ measured without disturbing the chromophores.…”

“…Full anisotropy could be restored with heat, however (which can be local and photoinduced, with appropriate device setup). The feasibility of storing B30 GB of data on a single layer of a removable disk using this gray-level approach has been demonstrated (Hagen and Bieringer, 2001).…”

“…An intriguing possibility for high density storage is to use angular multiplexing (Hagen and Bieringer, 2001). By storing multiple superimposed holograms in a single material, the data density is increased dramatically, and the whole 3-D volume of the material is exploited (Ramanujam et al, 2001).…”