As an important step towards graphene integration in silicon photonics, researchers from the Graphene Flagship have published a paper which shows how graphene can provide a simple solution for silicon photodetection in the telecommunication wavelengths.
Published in Nano Letters, this exciting research is a collaboration between the University of Cambridge (UK), The Hebrew University (Israel) and Johns Hopkins University (USA).
The mission of the Graphene Flagship is to translate graphene out of the academic laboratory, through industry and into society. This broad and ambitious aim has been at the forefront of the choices made to direct the Flagship; it focuses on real problem areas where it can make a real difference such as in Optical Communications.
Optical Communications are increasingly important because they have the potential to solve one of the biggest problems of our information age: energy consumption. Almost everything we do in everyday life consumes information and all of this information is powered by energy. If we want more and more information, we need more and more energy. In the near future, the major consumers of data traffic will be machine-to-machine communication and the Internet of Things (IoT).
To enable the IoT and the level of information it requires, current silicon photonics has a problem: it needs ten times more energy than we can provide. So, if we want this new, improved internet age, new technological, power-efficient solutions need to be found. This is why the drive to graphene-based optical communication is so important.
Over the last few years, optical communications have increased their viability over standard metal-based electronic interconnects. The current silicon-based photodetector used in optical communications has a major issue when it comes to detecting data in the near infrared range, which is the range used for telecommunications. The telecom industry has overcome this problem by integrating germanium absorbers with the standard silicon photonic devices. They have been able to make fully functioning devices on chips using this process. However, this process is complex.
In the new paper, graphene is interfaced with silicon on chip to make high responsivity Schottky barrier photodetectors. These graphene-based photodetectors achieve 0.37A/W responsivity at 1.55μm using avalanche multiplication. This high responsivity is comparable to that of the Silicon Germanium detectors currently used in silicon photonics.
Prof. Andrea Ferrari from the Cambridge Graphene Centre, who is also the Science and Technology Officer and the Chair of the Management Panel for the Graphene Flagship stated; “This is a significant result which proves that graphene can compete with the current state of the art by producing devices that can be made more simply, cheaply and work at different wavelengths. Thus paving the way for graphene integrated silicon photonics.”