Surface relief gratings generated by a photocrosslinkable polymer with styrylpyridine side chains

The formation of holographic surface relief gratings on thin films of a liquid-crystalline polymethacrylate with styrylpyridine side chains is described. A film of the polymer was treated with hydrogen chloride to protonate the side chain moieties, followed by holographic exposure to p-polarized Ar⁺ laser beams at 488 nm and by post-exposure baking to give rise to surface relief gratings. The depth of the surface relief in a typical case was 15 nm which is approximately 15% of the original film thickness. On the basis of the temperature dependence of diffraction efficiencies of the grating, the mechanism of the generation of the relief gratings is discussed.