Isomerization-induced surface relief gratings formation: A comparison between the probe and the matrix dynamics

We report molecular dynamics simulations of the effect of the photoisomerization of probe molecules on the nonequilibrium dynamics of a bulk amorphous matrix. Is it the matrix or the probe that drives the dynamics in SRG formation? In the first picture, the probe isomerization induces the motion of the probe inside the matrix. The motion of the probe then induces molecular motions inside the matrix. In the second picture, the probe isomerization induces a modification of the matrix diffusion mechanism. The diffusion of the matrix then induces the motion of the embedded probe. To answer this question, we compare the motion of the probe molecules and the motion of the matrix molecules in various thermodynamic conditions. We show that when the isomerization is switched on, the matrix molecules surrounding the probe move faster than the probe. Around the probe, the structural relaxation time of the matrix molecules is shorter than the probe relaxation time and the diffusion of the matrix molecules is larger than the probe diffusion. These results show that the matrix motions drive the dynamics

Simulation of isomerization-induced motions in a blend of different PMMA melts doped with DR1 chromophores

Date du colloque&nbsp;: 01/2010</p

Nonlocal communication with photoinduced structures at the surface of a polymer film

Nonlocal communication between two laser light beams is experimented in a photochromic polymer thin films. Information exchange between the beams is mediated by the self-induction of a surface relief pattern. The exchanged information is related to the pitch and orientation of the grating. Both are determined by the incident beam. The process can be applied to experiment on a new kind of logic gates.Comment: 7 pages, 4 figures, 2 table

Multistate polarization addressing using one single beam in an azo polymer film

Peculiar light-matter interactions can break the rule that a single beam polarization can address only two states in an optical memory device. Multistate storage of a single beam polarization is achieved using self-induced surface diffraction gratings in a photo-active polymer material. The grating orientation follows the incident light beam polarization direction. The permanent self-induced surface relief grating can be readout in real time using the same laser beam.Comment: 11 pages,3 figure

Spontaneous formation of optically induced surface relief gratings

A model based on Fick's law of diffusion as a phenomenological description of the molecular motion, and on the coupled mode theory, is developped to describe single-beam surface relief grating formation in azopolymers thin films. It allows to explain the mechanism of spontaneous patterning, and self-organization. It allows also to compute the surface relief profile and its evolution in time with good agreement with experiments