Electrostatic observations of laser-induced optical damage in LiNbO3

Abstract

A new technique for observing optical damage is reported. It is based on detecting electrostatic potentials which result from the laser-induced macroscopic charge separation responsible for optical damage. This new technique has been used to determine, for the first time, the charge distribution of the displaced charges. For uniform circular illumination of diameter D, the charges appear to reside in a thin cylindrical shell also of diameter D, with the negative charge on the positive ferroelectric axis. For a Gaussian illumination, we observe the charge distribution to change with increasing exposure time, approaching a cylindrical-shell charge distribution, a result which may provide an explanation for ’’optical clean-up’’. This new technique for probing optical damage is as sensitive as standard optical techniques and is unaffected by temperature variations and mechanical vibrations.