The demonstration of an integrated tuneable transmitter on silicon has been claimed as a first by a consortium of European companies.
The demonstrated single wavelength tuneable laser has a 21mA threshold at 20°C, 45nm tuning range and a side mode suppression ratio larger than 40dB over that tuning range. Its transmitter incorporates a hybrid III-V/Si laser-fabricated by direct bonding, which exhibits 9nm wavelength tuneability and a silicon Mach-Zehnder modulator with high extinction ratio of up to 10dB, leading to a bit-error-rate performance at 10Gbps.
Achieved as part of the European Union funded photonics project Helios, the integrated tuneable transmitter is said by its developers to represent a key milestone towards ‘fully integrated transceivers’. Helios is a four-year project that has the goal of making Complementary symmetry Metal Oxide Semiconductor (CMOS)-based photonics accessible to more users for electronics and telecommunication systems. CMOS is a technology that makes integrated circuit possible.
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.
French research organisation CEA-Leti, which is located in Grenoble, south east France, is a Helios member. CEA-Leti’s photonics programme manager is Laurent Fulbert. He said: ‘The ability to integrate a tuneable 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 centres, high performance computers as well as optical interconnects at rack-level and board-level.’
CEA-Leti demonstrated the integrated tuneable transmitter on silicon in collaboration with the III-V lab. The III-V lab is jointly owned by French companies Alcatel-Lucent and Thales. Other contributors to the project are the Ghent University-IMEC, which designed the laser, and the University of Surrey, which designed the modulator.