Pristine, undoped graphene has a constant absorption of 2.3 % across the visible to near-infrared (VIS-NIR) region of the electromagnetic spectrum. Under certain conditions, such as nanostructuring and intense gating, graphene can interact more robustly with VIS-NIR light and exhibit a large nonlinear optical response. Here, we explore the optical properties of graphene/LaAlO3/SrTiO3 nanostructures, where nanojunctions formed at the LaAlO3/SrTiO3 interface enable large (~108 V/m) electric fields to be applied to graphene over a scale of ~10 nm. Upon illumination with ultrafast VIS-NIR light, graphene/LaAlO3/SrTiO3 nanostructures produce broadband THz emission as well as a sum-frequency generated (SFG) response. Strong spectrally sharp, gate-tunable extinction features (>99.99%) are observed in both the VIS-NIR and SFG regions alongside significant intensification of the nonlinear response. The observed gate-tunable strong graphene-light interaction and nonlinear optical response are of fundamental interest and open the way for future exploitation in graphene-based optical devices.
@article{arxiv.1912.06952,
title = {Gate-Tunable Optical Nonlinearities and Extinction in Graphene/LaAlO$_3$/SrTiO$_3$ Nanostructures},
author = {Erin Sheridan and Lu Chen and Jianan Li and Qing Guo and Ki-Tae Eom and Hyungwoo Lee and Jung-Woo Lee and Chang-Beom Eom and Patrick Irvin and Jeremy Levy},
journal= {arXiv preprint arXiv:1912.06952},
year = {2020}
}
Comments
20 pages, 7 figures, supplementary information included