At this week’s IEEE International Electron Devices Meeting (IEDM 2014), nanoelectronics research center imec and its associated lab at Ghent University have demonstrated the industry’s first integrated graphene optical electro-absorption modulator (EAM) capable of 10Gb/s modulation speed. Combining low insertion loss, low drive voltage, high thermal stability, broadband operation and compact footprint, the device marks an important milestone in the realization of next-generation, high-density low-power integrated optical interconnects.
Integrated optical modulators with high modulation speed, small footprint and broadband athermal operation are highly desired for future chip-level optical interconnects. Graphene is a promising material to achieve this, owing to its fast tunable absorption over a wide spectral range. Imec’s graphene-silicon EAM consists of a 50µm long graphene-oxide-silicon capacitor structure implemented on top of a planarized silicon-on-insulator (SOI) rib waveguide. For the first time, high-quality optical modulation was demonstrated in a hybrid graphene-silicon modulator, at bit rates up to 10Gb/s. A competitive optical insertion loss below 4dB and extinction ratio of 2.5dB were obtained over a broad wavelength range of 80nm around 1550nm center wavelength. Moreover, no significant changes in performance were observed for temperatures in the range of 20-49°C, implying a robust athermal operation. As such, imec’s graphene-silicon EAM outperforms state-of-the-art SiGe EAMs on thermal robustness and optical bandwidth specifications.
“With this breakthrough result, imec has illustrated the huge potential of graphene optical EA modulators with respect to thermal, bandwidth, and footprint benefits,” said Philippe Absil, 3D and Optical Technologies department director at imec. “This achievement underscores our dedicated work and industry leadership in R&D on high bandwidth chip-level optical input/output. Future work will focus on further improving the modulation speed of our graphene EAM, similar to the speed obtained in highly optimized Si(Ge) modulators (30-50 Gb/s).”
Imec’s research on high-bandwidth optical input/output (I/O) explores optical solutions for realizing high-bandwidth chip-level I/O. With support by its associated lab at Ghent University it aims at developing a scalable, manufacturable silicon-based optical interconnect technology for the telecom and datacom industry. Imec’s portfolio includes low-loss strip waveguides, highly efficient grating couplers, 25Gb/s Mach-Zehnder modulators, 25Gb/s Ge photodetectors and more. Imec’s R&D on high bandwidth chip-level input/output is performed in cooperation with imec’s key partners in its core CMOS programs including Intel, Samsung, TSMC, Globalfoundries, Micron, Sony, SK Hynix, Huawei.
Imec recently joined the Graphene Flagship, Europe’s 1 billion EUR Programme covering the whole value chain from materials production to components and system. This will further strengthen imec’s strategic position in exploiting Graphene’s unique properties for optical interconnect applications.
Imec (imec.be) performs world-leading research in nanoelectronics and photovoltaics. Imec leverages its scientific knowledge with the innovative power of its global partnerships in ICT, healthcare and energy. Imec delivers industry-relevant technology solutions. In a unique high-tech environment, its international top talent is committed to providing the building blocks for a better life in a sustainable society. Imec is headquartered in Leuven, Belgium, and has offices in the Netherlands, Taiwan, US, China, India and Japan. Its staff of over 2,080 people includes more than 670 industrial residents and guest researchers. In 2013, imec’s revenue (P&L) totaled 332 million euro.
Imec is a registered trademark for the activities of IMEC International (a legal entity set up under Belgian law as a “stichting van openbaar nut”), imec Belgium (IMEC vzw supported by the Flemish Government), imec the Netherlands (Stichting IMEC Nederland, part of Holst Centre which is supported by the Dutch Government), imec Taiwan (IMEC Taiwan Co.) and imec China (IMEC Microelectronics (Shanghai) Co. Ltd.) and imec India (Imec India Private Limited).
About Ghent University and the Photonics Research Group
Ghent University (ugent.be), abbreviated to UGent, is one of the major universities in the Dutch-speaking region of Europe. It distinguishes itself as a socially committed and pluralistic university in a broad international perspective. It gets a first-rate ranking at a global level.
The Photonics Research Group in the Department of Information Technology of Ghent University performs research in the field of photonic integration more specifically silicon photonics and its applications in information and communication technology, in sensing and in life sciences. With its 80 researchers the group has a leading international role in the field and is also very active in graduate education in photonics and in industrial spin-off resulting from its research. The group is associated to imec.