Small-polaron based holograms in LiNbO₃ in the visible spectrum

Diffraction efficiency, relaxation behavior and dependence on pump-beam intensity of small-polaron based holograms are studied in thermally reduced, nominally undoped lithium niobate in the visible spectrum (λ = 488 nm). The pronounced phase gratings with diffraction efficiency up to η = (10.8 ± 1.0...

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Bibliographic Details
Published in:Optics express 2012-06, Vol.20 (12), p.13326-13336
Main Authors: Brüning, H, Dieckmann, V, Schoke, B, Voit, K-M, Imlau, M, Corradi, G, Merschjann, C
Format: Article
Language:English
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Summary:Diffraction efficiency, relaxation behavior and dependence on pump-beam intensity of small-polaron based holograms are studied in thermally reduced, nominally undoped lithium niobate in the visible spectrum (λ = 488 nm). The pronounced phase gratings with diffraction efficiency up to η = (10.8 ± 1.0)% appeared upon irradiation by single ns-laser pulses (λ = 532 nm) and are comprehensively assigned to the optical formation of spatially modulated densities of small bound NbLi4+ electron polarons, NbLi4+:NbNb4+ electron bipolarons, and O⁻ hole polarons. A remarkable quadratic dependence on the pump-beam intensity is discovered for the recording configuration K || c-axis and can be explained by the electro-optic contribution of the optically generated small bound polarons. We discuss the build-up of local space-charge fields via small-polaron based bulk photovoltaic currents.
ISSN:1094-4087
DOI:10.1364/OE.20.013326