title: Impact of the photorefractive and pyroelectric-electro-optic effect in lithium niobate on whispering-gallery modes.
abstract: 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.
authors.forename: Markus
authors.initials: M
authors.lastname: Leidinger
authors.forename: Christoph S
authors.initials: CS
authors.lastname: Werner
authors.forename: Wataru
authors.initials: W
authors.lastname: Yoshiki
authors.forename: Karsten
authors.initials: K
authors.lastname: Buse
authors.forename: Ingo
authors.initials: I
authors.lastname: Breunig