CEA-Leti and III-V lab demo fully integrated silicon photonics transmitter

GRENOBLE, FRANCE: CEA-Leti and III-V lab, a joint lab of Alcatel-Lucent Bell Labs France, Thales Research and Technology and CEA Leti, have demonstrated an integrated tunable transmitter on silicon. For the first time, a tunable laser source has been integrated on silicon, which represents a key milestone towards fully integrated transceivers.

The transmitter incorporates a hybrid III-V/Si laser-fabricated by direct bonding, which exhibits 9 nm wavelength tunability and a silicon Mach-Zehnder modulator with high extinction ratio (up to 10 dB), leading to an excellent bit-error-rate performance at 10 Gb/s. The results were obtained in the frame of the European funded project HELIOS, with the contribution of Ghent University-IMEC for the design of the laser and University of Surrey for the design of the modulator.

CEA-Leti and III-V lab also demonstrated single wavelength tunable lasers, with 21mA threshold at 20°C, 45 nm tuning range and side mode suppression ratio larger than 40 dB over the tuning range. These results will be overviewed during the Optical Fiber Communication conference 2012 in Los Angeles (USA) on March 4-8, 2012.

Silicon photonics is a very powerful technology, and CEA-Leti and III-V lab have now made a significant breakthrough in its development by integrating on the same chip complex devices such as a fully integrated transmitter working above 10Gb/s or a tunable single wavelength laser.

Silicon photonics has the promise of bringing the large scale manufacturing of CMOS to photonic devices that are still expensive due to a lack of ubiquitous technology. One big obstacle to silicon photonics is the lack of optical sources on silicon, the base material on CMOS.

“We can overcome this problem by bonding III-V material, necessary for active light sources, onto a silicon wafer and then co-processing the two, thus accomplishing two things at once,” explained Martin Zirngibl, Bell Labs Physical Technologies Research leader. “Traditional CMOS processing is still used in the process, while at the same time we now can integrate active light sources directly onto silicon.”

Based on the heterogeneous integration process developed by the CEA-Leti and III-V lab, III-V materials such as InP can be integrated onto silicon wafers. The fabrication process starts on 200mm Silicon on Insulator (SOI) wafers where the silicon waveguides and modulators are fabricated on CEA-Leti 200mm CMOS pilot line.

“We are proud to jointly present with III-V lab the results of the integrated silicon photonics transmitter and the tunable laser,” said Laurent Fulbert, Photonics Program Manager at the CEA-Leti France. “The ability to integrate a tunable laser, a modulator and passive waveguides on silicon paves the way of further developments on integrated transceivers that can address several application needs in metropolitan and access networks, servers, data centers, high performance computers as well as optical interconnects at rack-level and board-level. We are pleased to bring our contribution to these state-of-the-art results which can truly revolutionize optical communications.”