LETI announces integration milestone

12 Apr 2010

A European project unveils a fully CMOS-compatible laser source coupled to a silicon waveguide.

A team of researchers from across Europe will present details of a fully CMOS-compatible laser source that is coupled to a silicon waveguide this week. The achievement is a major milestone in a three-year €3.2m project known as WADIMOS (Wavelength Division Multiplexed Photonic Layer on CMOS). The ultimate goal of the project is to demonstrate a photonic interconnect layer on CMOS.

WADIMOS, an EU-funded research project, started in January 2008 and has six project partners. It is co-ordinated by IMEC of Belgium and also involves STMicroelectronics, MAPPER Lithography, Lyon Institute of Nanotechnologies (INL) and the University of Trento.

Working with a circuit design from INL and IMEC, LETI completed the specific process studies for the laser source by adapting and modifying standard III-V materials process steps to comply with a CMOS environment. Specifically, LETI replaced gold-based metal contacts with a Ti/TiN/AlCu metal stack. The circuits were processed on 200 mm wafers at LETI's facilities.

WADIMOS partners will present their results at this week's Photonics Europe conference in Brussels, which runs 12–16 April.

The enormous computing power of multi-processor systems and manufacturing tools being considered will require data transfer rates of more than 100 Terabit/s. These data rates may be needed on-chip, e.g. in multi-core processors, which are expected to require total on-chip data rates of up to 100 TB/s by 2015, or off-chip, e.g. in short-distance data interconnects, requiring up to 100 TB/s over a distance of 10–100 m. Optical interconnects are the only viable technology for transmitting these amounts of data.

Besides a huge data rate, optical interconnects also allow for additional flexibility through the use of wavelength division multiplexing. This feature may help realizing more intelligent interconnect systems such as the optical network-on-chip system that the WADIMOS project also is studying.

WADIMOS will build a complex photonic interconnect layer incorporating multi-channel microsources, microdetectors and different advanced wavelength routing functions directly integrated with electronic driver circuits. It also will demonstrate the application of the electro-photonic ICs in an on-chip optical network and a terabit optical datalink.