Optical cleaning owing to the bulk photovoltaic effect

B. Sturman, M. Kösters, D. Haertle, C. Becher, K. Buse
2009 Physical Review B  
It is shown within the conventional photovoltaic charge-transport model that photoexcitable electrons, localized at deep impurity levels, can be effectively removed by light from the exposed area at sufficiently high temperatures. This allows to modify strongly the absorption and photoelectric properties of the material and, in particular, to suppress "optical damage" in LiNbO 3 and LiTaO 3 crystals. This optical cleaning method is applicable to numerous pyro-and piezo-electric optical
more » ... ic optical materials. It employs the photovoltaic drift of electrons and ionic charge compensation at elevated temperatures. The physics of the optical cleaning is very rich; it has strong links to nonlinear dynamics and offers important handles for improvement of the cleaning performance. The use of properly moving light beams leads, e.g., to a strong enhancement of the cleaning rate and allows to reduce the electron concentration by several orders of magnitude. The theoretical predictions are supported by the data of our cleaning experiments with LiNbO 3 crystals. In particular, the intensity threshold of optical damage is increased by three orders of magnitude.
doi:10.1103/physrevb.80.245319 fatcat:ldzc7zppxfaavhdlx4wwevnqbm