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Fibre-Optics Data Boost from Graphene-Based Photodetectors

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Schematic of an infrared photodetector with graphene as its active element (Image Credit: AMO GmbH)

Infrared photodetectors in communications systems have traditionally been built as discrete devices connected to the optical fibre carrying the signal, and an electronic circuit for processing the received data. An improvement on this arrangement would be to integrate the detector and electronics on a single chip. This would substantially reduce the device footprint and fabrication cost. The maximum data rate achieved with a state-of-the-art germanium detector fabricated using the standard silicon-based CMOS production system for integrated circuits is 40 gigabits per second. However, the performance of such photodetectors is limited by the material properties, and is less than optimal, owing to silicon’s vanishing light absorption at the wavelengths used. This is driving the search for new and better materials, and graphene is considered a promising candidate.

In a paper recently published in the journal ACS Photonics, Daniel Schall and a team based at AMO in Aachen, and Alcatel-Lucent Bell Labs in Stuttgart, demonstrated photodetectors based on wafer-scale graphene. The devices are capable of recording data at up to 50 gigabits per second, and display excellent signal integrity.  Study leader Daniel Schall is a 32-year-old electrical engineer who has been with AMO since 2009, and is currently working toward a PhD at RWTH Aachen University. His work on graphene is supported by the European Commission through the Graphene Flagship.