title: Experimental demonstration of a transparent graphene millimetre wave absorber with 28% fractional bandwidth at 140 GHz.
abstract: The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz. Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.
authors.affiliation: 1] School of Electronic Engineering and Computer Science, Queen Mary University of London, London, E1 4NS, United Kingdom [2] School of Electronic Engineering, Xidian University, Xi'an, 710071, China.
authors.forename: Bian
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, United Kingdom.
authors.forename: Hatice M
authors.initials: HM
authors.lastname: Tuncer
authors.affiliation: School of Electronic Engineering and Computer Science, Queen Mary University of London, London, E1 4NS, United Kingdom.
authors.forename: Majid
authors.initials: M
authors.lastname: Naeem
authors.affiliation: 1] School of Electronic Engineering and Computer Science, Queen Mary University of London, London, E1 4NS, United Kingdom [2] Engineering, Sports & Sciences Academic Group, University of Bolton, Deane Road, Bolton, BL3 5AB, United Kingdom.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, United Kingdom.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Cole
authors.affiliation: Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, United Kingdom.
authors.forename: William I
authors.initials: WI
authors.lastname: Milne
authors.affiliation: School of Electronic Engineering and Computer Science, Queen Mary University of London, London, E1 4NS, United Kingdom.
authors.forename: Yang
authors.initials: Y
authors.lastname: Hao