30 December 2014

First silicon integrated graphene 10Gb/s optical electro-absorption modulator

The IMEC microelectronics center in Belgium claims the industry’s first silicon integrated graphene optical electro-absorption modulator (EAM) capable of 10 Gigabit/s modulation speed. The device was presented at the International Electron Devices Meeting (IEDM) in San Francisco on 15 December 2014 [Y Hu et al, session 5.6]. The work also involved IMEC’s associated lab at Ghent University.

Imec sees graphene as a promising material to achieve integrated optical modulators with high modulation speed, small footprint and broadband athermal operation, which are highly desired properties for future chip-level optical interconnects.

The device consisted of a 50µm-long graphene-oxide-silicon capacitor structure on top of a planarized silicon-on-insulator (SOI) rib waveguide. The EAM achieved optical insertion loss of less than 4dB with an extinction ratio of 2.5dB over a wavelength range of 80nm around 1550nm. Similar performance was maintained between 20°C and 49°C. The team claims that its device structure outperforms state-of-the-art silicon germanium (SiGe) EAMs on thermal robustness and optical bandwidth specifications.

“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 (30-50Gb/s),” comments IMEC’s 3D and Optical Technologies department director Philippe Absil.

Longer term, IMEC and Ghent aim to developed a scalable, manufacturable silicon-based optical interconnect technology for the telecom and datacom industry. Imec also recently joined the Graphene Flagship, Europe’s 1 billion Euro program covering the whole value chain from materials production to components and system.

Tags: SiGe EAM

Visit: www.imec.be

Visit: www.photonics.intec.ugent.be

The author Mike Cooke is a freelance technology journalist who has worked in the semiconductor and advanced technology sectors since 1997.