Photoinduced piezo-optical effect in Er doped ZnO films

A large increase of diagonal piezo-optic coefficient (up to 3.7×10−13m2∕N at λ=633nm) was observed in Er doped ZnO films under photoinduced treatment by two laser beams with frequencies of 1,060 and 530nm originating from the same Nd:YAG pulsed laser. It was demonstrated that piezo-optic effect is enhanced with increasing film thickness. This may be a consequence of the disturbance of the long range ordering in the nanocrystallites for the film with larger film thickness. The observed effect is explained due to Er ions creating additional local polarizability.