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DF: Fachverband Dielektrische Festkörper

DF 14: Electric, electromechanical and optical properties II

DF 14.7: Talk

Thursday, February 28, 2008, 16:00–16:20, EB 407

UV-assisted electrical field poling of magnesium-doped lithium niobate crystals* — •Hendrik Steigerwald, Fabian Luedtke, and Karsten Buse — Institute of Physics, University of Bonn, Wegelerstraße 8, 53115 Bonn, Germany

Periodically-poled lithium niobate (LiNbO₃) with domain structures in the micrometer regime is intensively investigated due to its increasing importance, e.g. for nonlinear optics using quasi phase matching. Efficient second harmonic generation in this material is usually hampered by optical damage, i.e. undesired index and absorption changes. Mg-doping increases the optical damage threshold, however complicates the poling process especially for small domain structures. We obtain such domain patterns in Mg:LiNbO₃ crystals by a combined approach using electric field poling and a superimposed UV light grating. Illumination with UV light decreases the coercive field of Mg:LiNbO₃ and enables smooth domain wall propagation. Structured coating of a z-cut Mg:LiNbO₃ crystal with UV-absorbing photoresist that has high electrical resistance enables electrical pulse poling of domain structures. The resulting domain patterns are investigated for different types of crystals and different poling parameters. Using this approach we also fabricated surface domains in proton exchanged α-phase waveguides.
*Financial support of the DFG and the Deutsche Telekom AG is gratefully acknowledged.