Photorefractive properties of lithium and copper in-diffused lithium niobate crystals

Abstract

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 ⌬n S , bulk photovoltaic current densities j phv , photoconductivities ph , and holographic sensitivities S are measured for light intensities up to 10 4 W/m 2 . 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 ␤* is 2 times larger, refractive-index changes are 7 times smaller, and the holographic sensitivity is up to 4 times larger.

<title>Propagation of a light beam in lithium niobate waveguide arrays: from discrete diffraction to discrete self-focusing</title>

“…The in-diffusion of Cu is performed during 10 -40 hours which results in the depth of Cu doping up to similar I mm. It is well known [6] that Cu doping significantly increases the photorefractive properties of LiNbO3. Thus, the waveguide arrays become buried within the layer of LiNbO3 wafer with pronounced photorefractive properties.…”

Photorefractive properties of undoped lithium tantalate crystals for various composition

“…Holographic measurements are performed with a twobeam interference setup as described, e.g., in Ref. 8. Two beams of an Ar + ion laser with a wavelength of = 488 nm are superimposed inside the crystal.…”

Structural, optical and thermal properties of Zr–Fe co-doped congruent LiNbO3single crystals

“…Generally, congruent LN (cLN) crystals exhibit photorefractive phenomena because of the presence of niobium antisites but have very low optical damage resistance in comparison with the stoichiometric LN, which makes cLN practically unusable. Normally, transition and rare earth metal ions (Fe, Mn, Cu and Ce) enhance the photorefractive properties of LN (Hesselink et al, 1998;Yang et al, 2003;Imbrock et al, 2002;Yang et al, 2000). Among these, Fe-doped LN has been studied intensively by various researchers not only for photorefractive application but also for applications such as pyroelectric infrared sensors and X-ray generation (Bayssie et al, 2005).…”