Laser-induced surface deformation and surface relief grating formation at d
ifferent intensity levels on azobenzene-functionalized polymer films were i
nvestigated. The surface deformation profile induced by a Gaussian laser be
am at low intensities reveals strong polarization dependence and establishe
s that an optical-field component in the direction of the optical-field gra
dient is essential for this deformation process. A theoretical analysis bas
ed on the optical-field gradient force model is presented to account for th
e deformation behavior at low intensities. In the higher-intensity regime,
however, a different mechanism is found to dominate the surface deformation
process. Simultaneous formation of two different types of topographic grat
ings is observed in a two-beam interference experiment. The phase relations
hip between these surface relief gratings and the interference intensity pa
ttern was deduced based on the results from the single-beam experiments. Th
e erasing behaviors of the two distinct surface relief gratings were experi
mentally investigated to highlight the two mechanisms involved in these gra
ting recordings. (C) 1999 American Institute of Physics. [S0021-8979(99)039
20-1].