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Impact of the photorefractive and pyroelectric-electro-optic effect in lithium niobate on whispering-gallery modes

: Leidinger, Markus; Werner, Christoph S.; Yoshiki, Wataru; Buse, Karsten; Breunig, Ingo


Optics Letters 41 (2016), No.23, pp.5474-5477
ISSN: 0146-9592
Journal Article
Fraunhofer IPM ()
lithium niobate; nonlinear optical materials; optical resonators; nonlinear optical devices

Whispering-gallery resonators made of undoped and MgO-doped congruently grown lithium niobate are used to study electro-optic refractive index changes. Hereby, we focus on the volume photovoltaic and the pyroelectric effect, both providing an electric field driving the electro-optic effect. Our findings indicate that the light-induced photorefractive effect, combining the photovoltaic and electro-optic effect, is present only in the non-MgO-doped lithium niobate for exposure with light having wavelengths of up to 850 nm. This leads to strong resonance frequency shifts of the whispering-gallery modes. No photorefractive effect was observed in the MgO-doped material. One has to be aware that surface charges induced by the pyroelectric effect result in a similar phenomenon and are present in both materials.