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DF: Fachverband Dielektrische Festkörper

DF 2: Optical and nonlinear optical properties, photonic

DF 2.5: Vortrag

Montag, 31. März 2014, 11:50–12:10, GER 37

Optical phonons and dielectric properties of LiNb_xTa_(1-x)O₃ — •Michael Rüsing¹, Christopher Buchholz¹, Gerhard Berth^1,2, Huajin Zhang³, and Artur Zrenner^1,2 — ¹Department Physik, Universität Paderborn, 33098 Paderborn, Germany — ²Center for Optoelectronics and Photonics Paderborn (CeOPP), 33098 Paderborn, Germany — ³State Key Lab of Crystal Materials, Shandong University, Jinan 250100, China

Recently Lithium-Niobate-Tantalate mixed crystals have drawn particular attention due to the possibility to tune the optical birefringence while sustaining its ferroelectric properties. A composition with zero birefringence at room temperature is of particular interest, as it represents an optical isotropic, but yet electrically polar material, which is unique in the class of ferroelectric materials.
Despite the unique properties only very few is known about the mixed crystals. Within this work Lithium-Niobate-Tantalate mixed crystals have been studied by polarization dependent µ-Raman spectroscopy. Furthermore the dielectric properties have been characterized via the Lyddane-Sachs-Teller-Relation. Here, all phonon modes exhibit a Vegard-like behaviour. In contrast to recent theoretical work on mixed crystals some phonons show a nonlinear shifting-behaviour, while all around a linear behaviour has been suggested. This also affects the dielectric properties.