title: Enhanced Graphene Photodetector with Fractal Metasurface.
abstract: Graphene has been demonstrated to be a promising photodetection material because of its ultrabroadband optical absorption, compatibility with CMOS technology, and dynamic tunability in optical and electrical properties. However, being a single atomic layer thick, graphene has intrinsically small optical absorption, which hinders its incorporation with modern photodetecting systems. In this work, we propose a gold snowflake-like fractal metasurface design to realize broadband and polarization-insensitive plasmonic enhancement in graphene photodetector. We experimentally obtain an enhanced photovoltage from the fractal metasurface that is an order of magnitude greater than that generated at a plain gold-graphene edge and such an enhancement in the photovoltage sustains over the entire visible spectrum. We also observed a relatively constant photoresponse with respect to polarization angles of incident light, as a result of the combination of two orthogonally oriented concentric hexagonal fractal geometries in one metasurface.
authors.forename: Jieran
authors.identifier: 0000-0002-4731-0482
authors.initials: J
authors.lastname: Fang
authors.forename: Di
authors.identifier: 0000-0002-3536-7027
authors.initials: D
authors.lastname: Wang
authors.forename: Clayton T
authors.initials: CT
authors.lastname: DeVault
authors.forename: Ting-Fung
authors.initials: TF
authors.lastname: Chung
authors.forename: Yong P
authors.initials: YP
authors.lastname: Chen
authors.affiliation: DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark , Lyngby, DK-2800, Denmark.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Boltasseva
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Shalaev
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Kildishev
keywords: Photodetector; fractal metasurface; graphene; plasmonics