Near-stoichiometric copper-doped lithium niobate crystals are fabricated by in-diffusion of thin layers of evaporated copper and a subsequent vapor transport equilibration treatment. The crystals are heated in a Li-rich atmosphere to increase the Li content. To determine the photorefractive properties, holographic as well as electrical measurements are performed. Saturation values of the refractive-index changes Δn<sub>S</sub>, bulk photovoltaic current densities j<sub>phv</sub>, photoconductivities σ<sub>ph</sub>, and holographic sensitivities <i>S</i> are measured for light intensities up to 10<sup>4</sup> W/m<sup>2</sup>. Comparison with experimental data of congruent crystals indicates that the specific photoconductivity is 15 times larger after a vapor transport equilibration treatment. The specific bulk photovoltaic coefficient β<sup>*</sup> is 2 times larger, refractive-index changes are 7 times smaller, and the holographic sensitivity is up to 4 times larger.
© 2002 Optical Society of America
Jörg Imbrock, Albert Wirp, Detlef Kip, Eckhard Krätzig, and Dirk Berben, "Photorefractive properties of lithium and copper in-diffused lithium niobate crystals," J. Opt. Soc. Am. B 19, 1822-1829 (2002)