Symmetry of the all-optical orientation dynamics of an octupolar azo-dye salt

Optical patterning of the molecular order in dye doped polymers offers inte resting and quite rich prospects. The generalization of the principles of h olography to the recording of an interference pattern between mutually cohe rent fields of different frequencies. such as fundamental and second harmon ic has been demonstrated to enable a full 3D polar control of the molecules . Together with exhibiting fairly large second order nonlinearities, donor- acceptor substituted azobenzene type materials were demonstrated to be very efficiently ordered materials under all-optical poling conditions. Photoin duced cis/trans isomerization results indeed in a free rotation of the mole cule leading to an efficient molecular redistribution following the molecul es selective polar excitation. In order to investigate the possible influen ce of the poling process on the resulting symmetry of the optically induced macroscopic susceptibility, a tetrahedral organotin azobenzene derivative was synthetized. All-optical orientation dynamics and symmetry of the secon d-order susceptibility chi ((2)) induced in PMMA rods doped with such a T-d space-group molecule are reported and discussed. The molecular relaxation dynamics is shown to have a determining influence on the symmetry resulting from the all-optical poling process. (C) 2000 Elsevier Science S.A. All ri ghts reserved.