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.

Graphene-enabled electrically switchable radar-absorbing surfaces

“…Through electrostatic doping, we show that atomically thin layers can be used as a switchable radar absorbing surfaces. Graphene and carbon nanotube-based composite materials have been used as resistive materials to absorb microwaves; however, to our knowledge they have not been used for active microwave surfaces [16][17][18][19][20][21][22][23][24][25][26][27] .…”

Breaking the black-body limit with resonant surfaces

“…Furthermore, so-called perfect metamaterial absorbers have been fabricated with sole use of metallic elements which are experimentally tested with excellent results [8], and are examined in alternative structures [9,10]. Other interesting designs in the visible spectrum [11,12], the sub-THz spectrum [13] and at radio frequencies [14] have been reported to exhibit high efficiency combined with broadband features.…”

Electromagnetic Characterisation of Materials by Using Transmission/Reflection (T/R) Devices

“…It has also aroused the interest of the scientific community towards other two-dimensional, or quasi-2D, materials, which are receiving increasing attention thanks to the development of printable electronics technology, which allows fast and low-cost prototyping and fabrication of device like antennas [2][3][4], periodic surfaces [5,6], or sensors and tags [7][8][9]. Those kinds of application require highly conductive inks that may exhibit high losses, which, in turn, can be exploited for the design of absorbing materials [10][11][12][13][14][15] and for electromagnetic signature control [16]. The applicability of these techniques has been recently pushed to above 100 GHz using reverse offset (RO) printing, which allows high line-resolution and increases printing speed [17,18].…”