A model for the formation of holographic surface relief gratings in azobenzene functionalized polymers is presented. Forces leading to migration of polymer chains upon exposure to light in the absorption band of the azo chromophore are attributed to dipoles interacting with the gradient of the electric field present in the polymer material. Efficient trans–cis cycling in the azobenzenes allows cooperative movement of the chromophores under the influence of gradient forces.

Large-amplitude holographic surface relief gratings on azobenzene-containing polymer films were optically induced without any subsequent processing steps. The surface relief structures were observed upon exposure to an interference pattern of polarized Ar+ laser beams. The surface relief structures were investigated using atomic force microscopy. A very regularly spaced surface grating with a surface modulation depth of over 1000 A was obtained. The gratings were stable at ambient conditions, and the samples were reusable after erasing the gratings by heating the film above the glass transition temperature. The orientation 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 azobenzene groups is discussed. Thermal effects were also investigated by studying the dependence of the writing intensity and grating spacing on the grating formation process.The intensities of the writing beams were well below the power required for ablation of the polymer. The gratings could be erased by heating the polymer film

Polarization controlled semicondcutor photonic devices by strainedbarrier superlattice structures AIP Conf. Proc. 227, 184 (1991); 10.1063/1.40649 Surface chemistries and electronic properties of molecular semiconductor thin films grown by effusion beams AIP Conf.

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An epoxy based polymer with nonlinear optical azo chromophores was designed to contain anionic groups to induce water solubility and self assembly. Using this polyanion with a polycation, multilayers were prepared on a glass substrate by alternating adsorption from dilute aqueous solutions. The azo chromophores in the confined layer of the polyanion in the multilayer films self-assemble into a noncentrosymmetric alignment and demonstrate second order optical nonlinearity (d33 = 19 pm/V).