Open AccessSmall-polaron based holograms in LiNbO_3 in the visible spectrum
Author(s) -
H. Brüning,
Volker Dieckmann,
B. Schoke,
Kay-Michael Voit,
Mirco Imlau,
G. Corradi,
Christoph Merschjann
Publication year - 2012
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.013326
Subject(s) - polaron , optics , materials science , diffraction efficiency , lithium niobate , holography , relaxation (psychology) , photorefractive effect , diffraction , phase (matter) , electron , molecular physics , physics , psychology , social psychology , quantum mechanics
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.