Researchers at The University of Central Florida have come up with a finding that enables graphene to better absorb light and showed more than 45% absorption of light in a single layer of graphene. This may open the door to graphene-enhanced applications that require the incident light to be fully utilized, like next-generation light detectors, touchscreens, and more.
“This is the first published work on extremely high light absorption in graphene which is tunable dynamically,” the researchers said. “Theoretical studies show further design optimization can lead to further enhanced absorption close to 90%”.
The UCF teams received $544,000 from the Defense Advanced Research Agency’s (DARPA) Wafer Scale Infrared Detectors program (WIRED) Phase-I for 18 months. Recently the teams also obtained a Phase-II award for $419,000 to continue its work over the coming 12 months.
The team members did not attempt to alter the properties of the graphene in any way. Instead, they placed the graphene on a polymer substrate as a support layer and stamped it using a polymeric stamp to form a nanoscale pattern on the pristine graphene. An optical cavity stopped light from escaping and repeatedly bounced light back to the patterned graphene layer and enhanced light absorption. In addition, the process allows voltage driven change in electron energy and thus in the electron density, enabling absorption of different wavelengths of light – making the process dynamically tunable.
The team said the work is of special interest to DARPA because of the need for tunable infrared cameras that can operate at room temperature and can be used to develop multispectral night vision equipment, gas and chemical sensors. A multispectral imaging capability will enable infrared imaging across various bands with the same camera, revealing further detailed information about the object – important for space exploration and many United Stated Department of Defense specific applications.