New research from scientists in the UK examines graphene’s ability to absorb electromagnetic radiation with the creation of optically transparent broadband absorbers operating in the millimeter frequency range.
Since graphene’s isolation by University of Manchester scientists in 2004, research efforts worldwide have focused on harnessing its unique electrical, optical, mechanical and thermal properties for use in a variety of applications. Until recently, says the research team, most graphene research have focused on the terahertz and optical frequencies, while practical applications of graphene have included the development of graphene-based FET mixers, RF transistors and controllable resistive devices such as metasurfaces, and absorbers. The experimental demonstration of transparent radio-frequency absorbers with broadband properties, however, still requires further research.
Now, researchers at the Queen Mary University of London and the Cambridge Graphene Centre have fabricated transparent broadband absorbers consisting of several stacked multilayer graphene sheets on quartz substrates backed with a ground plate. According to the team, use of the graphene in the broadband absorbers increased the absorption of electromagnetic energy by 90 percent over a wide bandwidth, making it suitable for a variety of applications including more robust electromagnetic shielding and more efficient communication devices. Their research is published in the journal Scientific Reports.
“The technological potential of graphene is well-known. This paper demonstrates one example of how that potential can translate into a practical application,” Yang Hao, co-author of the study and professor of antennas and electromagnetics at Queen Mary’s School of Electronic Engineering and Computer Science, said.
“The transparent material could be added as a coating to car windows or buildings to stop radio waves from traveling through the structure. This, in turn, could be used to improve secure wireless network environments, for example.”
To create the new broadband absorbers, the researchers placed a stack of multilayer graphene sheets on quartz substrates backed with a ground plate. The large-area CVD multilayer graphene films were fabricated through a repeated etch-and-transfer process to minimize PMMA residue between the layers.
“The stacking configuration gives us better control of the interaction between radio waves and the graphene,” co-author Bian Wu, who is at Queen Mary from Xidian University in China on a scholarship from the China Scholarship Council, explained.
The team is currently focused on developing prototypes with the aim of moving graphene from lab-based research to engineering applications.
