Light-induced charge transport in LiNbO_3:Fe at high light intensities

Abstract

In LiNbO₃ at light intensities above 10⁶ W/m² much stronger refractive index changes can be induced, as expected from measurements at low intensities. Most experimental data have been published on iron-doped LiNbO₃ crystals. We propose a two-center charge-transport model for LiNbO₃:Fe that describes most results at low and high intensities quantitatively. It explains the intensity dependence of steady-state refractive index changes and enhanced holographic sensitivities at high light intensities as well as the presence of light-induced absorption changes.