Observation of light polarization-dependent structural changes in chalcogenide glasses.

The atomistic origin of photoinduced vector (polarization-dependent) phenomena in As-Se films is determined by extended x-ray absorption fine structure with in situ exposure to polarized laser light. A vector structural change is observed directly for any material: there is an expansion of the nearest-neighbor distance around the Se atoms, the magnitude of which depends on the direction of light polarization; the effect around As atoms is relatively smaller. The results point to the origin of scalar as well as vector changes in properties, which either persist after the light is removed, or exist only when light is incident on the sample. [ABSTRACT FROM AUTHOR]