Light-induced charge-transport in undoped LiNbO3 crystals

Light-induced charge transport in nominally undoped LiNbO3 crystals essentially differs from that in Fe- and Cu-doped crystals. Furthermore, it is of relevance for numerous effects ranging from optical damage to domain reversal. Here, we review the state of the art of the studies of light-induced charge transport in this important material. This includes a summary of the facts known for doped crystals, a description of the experimental methods relevant to undoped crystals, a summary of the main experimental data for this material, especially the data on the intensity dependences, presentation of the methods of purification from unwanted photo-active electrons, and a discussion of possible mechanisms responsible for the charge-transport peculiarities.