CEA-Leti has successfully demonstrated a fully packaged CWDM optical transceiver module with data transfer of 100Gb/s per fibre with a low-power-consumption electronic chip co-integrated on the photonic chip.

This silicon-photonics-based transceiver multiplexes two wavelengths at 50Gb/s and has been designed to meet the ever-increasing data-communication demands and energy use of data centres and supercomputers.

The EU H2020 project, COSMICC, further developed all the required building blocks for a transmission rate of 200Gb/s and beyond without temperature control with four 50-Gb/s wavelengths and by aggregating a large number of fibres.

According to CEA-Leti, the key breakthroughs have been the development of broadband and temperature-insensitive silicon nitride (SiN) multiplexing components on silicon (Si), the integration of hybrid III-V/Si lasers on the Si/SiN chips and a new high-count adiabatic fibre-coupling technique via SiN and polymer waveguides.

This demonstration opens the way to technology that will allow a reduction in the cost, the power consumption and the packaging complexity and opens the way to reaching a very high aggregated data rate beyond terabits per second (Tb/s).

Starting with STMicroelectronics’ silicon photonics integration platform, the COSMICC project has developed a coarse wavelength division multiplexing (CWDM) silicon-photonics transceiver in a packaged module at 100Gb/s per fibre. It is scalable to 400Gb/s and includes 3D assembly of a silicon photonic chip and its electronic control chip.

The silicon photonic chip integrated high-performance 50Gb/s NRZ optical modulators and photodetectors, and a two-channel CWDM multiplexer and demultiplexer. The control electronics have been optimised to limit energy consumption, down to 5.7 pJ/bit per channel at 50Gb/s data rate.

Separately, a library of enabling building blocks for higher data-rate datacentre interconnects has been built on a SiN-enhanced silicon photonics platform, including new broadband and athermal SiN components and hybrid III-V/Si lasers. SiN, which is 10 times less sensitive to temperature than silicon, has been able to dramatically reduce the transceiver cost and power consumption by eliminating the need for temperature control and will thus contribute to the reduction of the heat output and cooling costs of mega datacentres.

CEA-Leti scientist Ségolène Olivier, who coordinated the project, said development of modulators and photodetectors at 50Gb/s and their co-integration with their control electronics was a breakthrough that led to the low-power consumption 100Gb/s transceiver module.

“In addition, the new building blocks are essential for addressing the need for terabit-per-second transceivers at low cost and low energy consumption to sustain the exponential growth of data traffic in datacentres and in high performance computing systems,” she explained. “COSMICC’s technology will answer tremendous market needs with a target cost per bit that traditional WDM transceivers cannot meet."

In addition to CEA-Leti, COSMICC consortium members include:

  • Industry: STMicroelectronics Italy & France, Vario-Optics, Seagate, Finisar
  • Academic & institutional: Université Paris Sud, Universita di Pavia, University of Southampton Optical Research Centre, University of Saint Andrews, Cork Institute of Technology
  • Consultants: Ayming