Optically induced birefringence and surface relief gratings in composite Langmuir-Blodgett (LB) films of poly[4′-[[2-(methacryloyloxy)ethyl]ethylamino]-2-chloro-4-nitroazobenzene] (HPDR13) and cadmium stearate

Photoinduced trans-cis-trans isomerization, optical storage, and surface relief gratings are demonstrated in mixed Langmuir-Blodgett (LB) films of poly[4'-[[2-(methacryloyloxy)ethyl]ethyl amino]-2-chloro-4-nitroazobenzene] (HPDR13) and cadmium stearate (CdSt). The trans-cis-trans photoisomerization of the azobenzene chromophores from HPDR13 in the mixed LB him was achieved with a circularly polarized laser light. The birefringence induced by a linearly polarized laser light decreased with the number of layers and increased with the weight percentage of HPDR13 in the mixed LB film. The surface relief gratings recorded by exposing the mixed LB film to an interference pattern produced by the laser light were visualized through atomic force microscopy (AFM). Interestingly, it seems that the nonphotoactive CdSt domains have also migrated along with HPDR13 while recording the surface relief gratings.