Blends of polymethylmethacrylate (PMMA) and diblock methacrylic azopolymers have been investigated for holographic storage with short light pulses. Transmission electron microscopy measurements show that the dilution of the block copolymer in PMMA changes the microstructure from a lamellar to a spherical morphology. Besides the optical anisotropy induced with linearly polarized 488 nm light is smaller and less stable in the blends than in the block copolymer films. Holographic gratings induced with light pulses of 1 s are not as stable as the ones achieved with writing times of several minutes (both in the blend and in the block copolymer) but a final efficiency remains. Up to 20 polarization gratings have been multiplexed, using light pulses of 1 s, 300 ms and 100 ms, in thick (500 mu m) blend films. The equilibrium values of the efficiencies are higher than 10(-5) for all the gratings. An angular resolution of about 0.5 degrees has been achieved in these thick gratings.
- volume holography
- block copolymers