POLARIZED LASER-INDUCED HOLOGRAPHIC SURFACE-RELIEF GRATINGS ON POLYMER-FILMS

Large-amplitude holographic surface relief gratings on azobenzene-cont aining polymer films were optically induced without any subsequent pro cessing steps. The surface relief structures were observed upon exposu re to an interference pattern of polarized Ar+ laser beams. The surfac e relief structures were investigated using atomic force microscopy. A very regularly spaced surface grating with a surface modulation depth of over 1000 Angstrom was obtained. The gratings were stable at ambie nt conditions, and the samples were reusable after erasing the grating s by heating the film above the glass transition temperature. The orie ntation of the azobenzene groups was induced first and followed by the surface deformation process. The polarization of the writing beam had a significant effect on the surface modulation process. The relation between the surface change and optically induced orientation of the az obenzene groups is discussed. Thermal effects were also investigated b y studying the dependence of the writing intensity and grating spacing on the grating formation process.