Depth-resolved photorefractive characterization of lithium niobate doped with iron by thermal diffusion

Iron doping of lithium niobate crystals by thermal diffusion is a well-established technique for the realization of spatially confined photorefractive stages in integrated optical devices. In this paper we present an innovative method able to realize depth-resolved holographic measurements inside the iron-diffused layer, so that in-depth profiles of the main photorefractive parameters can be derived without the need of any waveguide. By means of this technique it is possible to achieve a better knowledge of the influence of different surface treatments on the photorefractive performances of iron-diffused layers and to link them to the results of other depth-resolved characterization techniques in the framework of microscopic models of photorefractivity.