Blends of an azomethacrylic block copolymer for volume holographic storage using low energy 10ms light pulses

Polymer blends of a poly (methylmethacrylate) (PMMA) homopolymer and an azomethacrylic diblock copolymer (BC) are investigated for the recording of holographic polarization gratings. Blends with an azobenzene content down to 2, 1 and 0.5 wt.%, and good optical quality have been prepared. Their morphology associated with microphase separation as well as the achieved photo-induced anisotropy in terms of birefringence and dichroism are similar to those obtained for the original BC. Volume holographic polarization gratings have been stored in thick films (up to 500 μm) of these blends using two oppositely circularly polarized 488 nm light pulses of 100 ms and 10 ms with a constant value of the energy density of 50 mJ/cm2 (each beam). Although the efficiency of the gratings decays with time, a final equilibrium efficiency, in the range of 10-4, remains in both cases. Up to 20 polarization gratings, with efficiencies higher than 3.5 × 10-5, have been successfully multiplexed using light pulses as short as 10 ms, which is an order of magnitude shorter than that reported in previous investigations. © 2012 Elsevier B.V. All rights reserved.