By G.P. Thomas
Graphene -- a two dimensional sheet made of carbon atoms -- can convert light into electrical current. Image Credit: TU Vienna
Graphene light detectors have been successfully combined with semiconductor chips, with potential benefits for large computer networks.
The benefits of graphene in computer chips have not come as a surprise, but rather a
vindication, for the team of scientists at the Vienna University of Technology, which demonstrated the suitability of graphene for converting light into electrical current two years ago. Their recent work has been published in the journal "Nature Photonics".
Nor is this the first time that a similar integration has been attempted – many materials can convert light into electrical signals, and previous work has been undertaken utilising elements such as germanium.
However, these materials can often only process specific wavelengths of light, whereas graphene converts all light frequencies needed for telecommunications equally well.
Furthermore, the speed of conversion using graphene is extremely fast compared to other materials, meaning a large amount of data can be transmitted in a short period of time.
Thomas Muller, assistant professor at the Vienna University of Technology’s Photonics Institute, explains this conversion further.
"A narrow waveguide with a diameter of about 200 by 500 nanometers carries the optical signal to the graphene layer. There, the light is converted into an electrical signal, which can then be processed in the chip".
Another benefit of using graphene photodetectors is that given their size, many can be implemented on a single chip. Theoretically, 20 000 different information channels could sit on one semiconductor chip.
This could be an important breakthrough for data large networks of computers, as data exchange would become much faster and it would require much less electrical energy.
"These technologies are not only important for transmitting data over large distances. Optical data transmission also becomes more and more important for communication within computers" - Thomas Müller
Interestingly, in the same issue of Nature Photonics, researchers from MIT have also published similar findings on graphene photodetectors, using a slightly different geometry.
This is surely an indication that graphene continues to be a central theme in many fields of scientific research, and signposts yet another step towards the real-world application of graphene.
The light signal arrives through a waveguide (left), in the 2 micrometer wide graphene sheet, electrical current is generated. Image Credit: TU Vienna