Leti, the Laboratory for Electronics & Information Technology within the French research and technology organization CEA, has demonstrated a fully CMOS-compatible laser source coupled to a silicon waveguide, a major milestone toward the Wadimos project's goal of fabricating silicon photonics circuits in CMOS foundries. Wadimos is an abbreviation of 'wavelength division multiplexed photonic layer on CMOS.'
Wadimos is an EU-funded research project to demonstrate a photonic interconnect layer on CMOS. Leti’s partners in the project, which is coordinated by Imec, include STMicroelectronics, Mapper Lithography, Lyon Institute of Nanotechnology (ILN) and the University of Trento.
Working with a circuit design from INL and Imec, Leti completed the specific process studies for the laser source to adapt and modify standard III-V materials process steps that would comply with a CMOS environment. Leti replaced gold-based metal contacts with a Ti/TiN/AlCu metal stack.
The technology under development is said to have applications in high-performance computing, where optical interconnects will be able to transmit huge amounts of data at high rates. Optical interconnects also allow for additional flexibility through the use of wavelength division multiplexing. This feature may be help realise more intelligent interconnect systems such as the optical network-on-chip system that the Wadimos project also is studying.
The Wadimos project's aim is to 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 aims to demonstrate the application of the electro-photonic ICs in an on-chip optical network and a terabit optical datalink.