Femtosecond Laser Based Polarization Storage by Direct-Writing in Diazobenzene Copolymer Film

Femtosecond laser-based polarization storage by two-photon isomerization of chromophores has been intensively researched in recent years due to the potential capacity of multiple storage density. In this paper, we present a rewritable multilayer polarization storage method by direct-writing in a photoisomeric copolymer film. The influence of exposure time on the readout bit size is investigated. Dual-layer storage is achieved by placing a transparent spacer between two layers. It is found that the recorded information can be completely erased by circularly polarized laser. The contrast changes during erasing process are also studied.