This is an application of what is know as silicon photonics which is expected to bringing the large scale manufacturing of CMOS to photonic devices. One big obstacle to silicon photonics is the lack of optical sources on silicon, the base material on CMOS.
The transmitter incorporates a hybrid III-V/Si laser-fabricated by direct bonding, which exhibits 9nm wavelength tunability and a silicon Mach-Zehnder modulator which can be used for 10Gbit/s data transmisison in optical fibre systems.
“We bond 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.
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.
“Traditional CMOS processing is still used in the process, while at the same time we now can integrate active light sources directly onto silicon,” said Zirngibl.
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.
The results were obtained in the frame of the European funded project HELIOS (www.helios-project.eu), with the contribution of Ghent University-IMEC for the design of the laser and University of Surrey for the design of the modulator.
These results will be overviewed during the Optical Fiber Communication conference 2012 in Los Angeles (USA) on March 4-8, 2012.