Photoinduced anisotropy in photobleached Ge-As-S films

Linear optical dichroism and birefringence induced by linearly polarized li ght were studied in the photobleached optically isotropic three-component G exAs40-xS60 films. The anisotropy can be erased by nonpolarized or circular ly polarized light. Multiple reorientation under the action of linearly pol arized light with orthogonal orientation of the electrical vector was inves tigated. The anisotropy relaxes gradually in the dark with a large time con stant. The sign of dichroism was the same as in the binary As-Se and As-S p hotodarkened chalcogenide films. Therefore, the inducing polarized light al ways decreases the absorption of the light polarized parallel to itself. Ph otodarkening instead of photobleaching was observed in annealed films. Anne aling resulted also in a strong decrease of photoinduced anisotropy that is different from the behaviour of binary chalcogenide films. (C) 2001 Elsevi er Science B.V. All rights reserved.