Charge transport properties of undoped congruent lithium niobate crystals

Time-resolved light-induced birefringence measurements based on a phase compensation technique are used to determine the charge transport properties of congruent, nominally-undoped lithium niobate crystals (LiNbO(3)). Some of the crystals are conventionally oxidized. The steady-state space-charge field E (pv), the bulk photovoltaic coefficient beta, and the photoconductivity sigma (ph) are determined in the intensity range (30-30 000) W/cm(2). The photovoltaic coefficient beta increases by one order of magnitude over this intensity range, the space-charge field E (pv) even by two orders of magnitude. We discuss the results in the context of the known one- and two-center charge transport models for LiNbO(3). The experimental findings presented here are of relevance for the long-standing problem of optical damage in such crystals, which inhibits their use in high-intensity applications like nonlinear optics.