Open AccessAdvanced analysis of domain walls in Mg doped LiNbO_3 crystals with high resolution OCT
Author(s) -
Lars Kirsten,
Alexander Haußmann,
Christian Schnabel,
Sebastian Schmidt,
Peter Cimalla,
Lukas M. Eng,
Edmund Koch
Publication year - 2017
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.25.014871
Subject(s) - lithium niobate , optics , optical coherence tomography , materials science , refractive index , dispersion (optics) , ferroelectricity , amplitude , doping , resolution (logic) , optoelectronics , physics , computer science , dielectric , artificial intelligence
The structure of domain walls (DW) in ferroelectric media is of great interest as this material is used for frequency doublers and other applications. We show that the structure of the DWs can nicely be visualized by high resolution optical coherence tomography (OCT). While the high group refractive index of lithium niobate allows a resolution much better than 1 µm, the large dispersion can blur the image and has to be compensated. Therefore, we developed an adaptive dispersion compensation algorithm based on maximizing the intensity of the DWs. By measuring a group of DWs, the mean period of the DWs could be measured with an accuracy of less than 10 nm differentiating samples with only 30 nm distinct periods. By analyzing the peak position, amplitude and phase shift within a DW, we were able to determine steps in the DW of only 50 nm. Furthermore, the inclined course of the DWs in a fan-shaped frequency doubler could be displayed. Therefore, we conclude that OCT is able to provide valuable information about the structure of domain walls in periodically poled lithium niobate (PPLN).