Using laser-like energy conversion methods, a team of physicists from MIPT and Vladimir State University in Russia have successfully converted light energy into surface waves on the surface of graphene with 90% efficiency, Phys.org reports.
The breakthrough could lead to ultracompact devices for converting and storing optical energy. In order to confine the light at the nanoscale, Phys.org says the team converted optical radiation into what is known as surface plasmon-polarations (SPPs), which vary in strength depending on what material they rest on. 2D materials like graphene have high refractive indices, which is how the 90% efficiency was possible.
This is considerably more efficient than standard methods. Typically the process of converting light energy to SPPs on 2D surfaces has an efficiency no higher than 10%, although that figure can be improved using intermediary signal converters. In this new research, the team used semiconductor quantum dots between 5-100 nanometers as intermediary signal converters to achieve their high efficiency.
“We investigated a scheme where a quantum dot positioned above graphene interacts both with incident light and with the surface electromagnetic wave, but the frequencies of these two interactions are different. The dot interacts with light at a wavelength of 1.55 micrometers and with the surface plasmon-polariton at 3.5 micrometers. This is enabled by a hybrid interaction scheme,” said study co-author Alexei Prokhorov.”