Open AccessQuantifying the refractive index of ferroelectric domain walls in periodically poled LiNbO3single crystals by polarization-sensitive optical coherence tomography
Author(s) -
Jonas Golde,
Michael Rüsing,
Jan Rix,
Lukas M. Eng,
Edmund Koch
Publication year - 2021
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.432810
Subject(s) - refractive index , optical coherence tomography , materials science , optics , ferroelectricity , polarization (electrochemistry) , lithium niobate , nanoscopic scale , optoelectronics , nanotechnology , physics , dielectric , chemistry
Domain walls (DWs) in ferroelectric (FE) and multiferroic materials possess an ever-growing potential as integrated functional elements, for instance in optoelectronic nanodevices. Mandatory, however, is the profound knowledge of the local-scale electronic and optical properties, especially at DWs that are still incompletely characterized to date. Here, we quantify the refractive index of individual FE DWs in periodically-poled LiNbO 3 (PPLN) single crystals. When applying polarization-sensitive optical coherence tomography (PS-OCT) at 1300 nm using circular light polarization, we are able to probe the relevant electro-optical properties close to and at the DWs, including also their ordinary and extraordinary contributions. When comparing to numerical calculations, we conclude that the DW signals recorded for ordinary and extraordinary polarization stem from an increased refractive index of at least Δn > 2·10 -3 that originates from a tiny region of < 30 nm in width. PS-OCT hence provides an extremely valuable tool to decipher and quantify subtle changes of refractive index profiles for both inorganic and biomedical nanomaterial systems.