Two-photoactive-center model applied to photorefractive self-focusing in biased LiNbO3
Abstract
We propose a time-dependent, three-dimensional numerical model where iron impurities and polarons are both considered photoactive centers to explain beam self-trapping in biased lithium niobate crystal. It shows that the intensity-dependent behavior reported experimentally is due to the competition between the drift current and the nonlinear photovoltaic current. For low light intensity, beam self-focusing occurs, while beam-splitting is observed at a higher intensity level.
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