IR Technique Allows Researchers to See Through Graphene Layers
12 December 2013
Researchers at the University of Buffalo have brought to life a unique infrared (IR) technique that can see through a stack of graphene layers, distinguishing and characterizing the electronic properties of each sheet. The information derived could pave the way for the creation of graphene-based optical devices for communications, imaging and signal processing.
The technique involves shooting a beam of IR light at the stack and tracking the changes occurring in the light wave's direction of oscillation as it rebounds off the layers within. Once a wave is reflected by a graphene sheet the direction of oscillation changes, a process known as polarization, allowing the researchers to describe the electronic properties of sheets stacked on top of one another even if they are covering each other up.
It should be noted that different types of graphene change polarization in different ways if a magnetic field is applied and increased. For instance, a graphene layer stacked neatly on top of another will impact polarization in a different way than a layer that is messily stacked. This is because different layers absorb and emit light in different ways, John Cerne, an associate professor at the university and author of the research, explained.
The study, which included researchers from the US Naval Research Laboratory, also revealed a change in absorption and emission patterns when a magnetic field is applied, suggesting that polarization can be turned on and off by applying a magnetic field. The process could be accelerated if a voltage that releases electrons through the graphene is applied, providing for faster modulation and setting the stage for the development of novel optical devices using graphene.