Three independent teams have boosted the performance of photodetectors that use graphene (atomically thick sheets of carbon) to convert light into electrical signals. This may enable fast optical communication within and between computer chips.
The latest devices boast data-transmission rates that rival those of conventional components and can sense a broader range of light wavelengths. Earlier graphene models produced weaker currents because most of the light failed to interact with their carbon layers. All three groups solved that problem by channelling light through silicon waveguides running along the graphene sheet.
The device built by Thomas Mueller at the Vienna University of Technology and his team produces 50 milliamps of current per watt of infrared light — only ten times less than germanium photodetectors, the current standard.
Dirk Englund of the Massachusetts Institute of Technology in Cambridge and his co-workers made a similar detector that handles an impressive 12 gigabits of data per second, and produces a clean electrical signal (pictured).
Meanwhile, a device from the group of Xiaomu Wang, then at the Chinese University of Hong Kong, picks up mid-infrared light at room temperature, suggesting that graphene detectors could bypass the restrictive cooling requirements of other photodetector materials.
Nature Photon. http://doi.org/ns8; http://doi.org/ns9; http://doi.org/ntb (2013)