Graphene is key to fast light-to-current converter

Scientists at the Vienna University of Technology have combined a graphene photodetector with a standard silicon chip that can transform light into electrical signals, a development that could lead to improved telecommunications.

The research began two years ago when Thomas Müller and colleagues from the Institute of Photonics at Vienna University of Technology demonstrated that graphene is suited to turn light into electrical current.

‘There are many materials that can transform light into electrical signals, but graphene allows for a particularly fast conversion’, Müller said in a statement.

‘A narrow waveguide with a diameter of about 200nm by 500nm carries the optical signal to the graphene layer,’ added Müller. ‘There, the light is converted into an electrical signal, which can then be processed in the chip.’

There have already been attempts to integrate photodetectors made of other materials – such as germanium – directly into a chip. However, these materials can only process light of a specific wavelength range. The researchers were able to show that graphene can convert all wavelengths which are used in telecommunications.

As well as being very fast, around 20,000 detectors can fit onto a single chip with a surface area of one square centimetre. Theoretically, the chip could be supplied with data via 20,000 different information channels.

‘These technologies are not only important for transmitting data over large distances. Optical data transmission also becomes more and more important within computers themselves’, said Müller.

The Viennese team worked with researchers from the Johannes Kepler University in Linz and the results of their work have been published in Nature Photonics.