Collaboration at Leti to advance silicon photonics beyond 1Tb/s

November 22, 2016 // By Graham Prophet
The research organisation Leti (Grenoble, France) has announced the launch of a European Commission Horizon 2020 project to enable mass commercialization of silicon-photonics-based transceivers to meet future data-transmission requirements in data centres and super computing systems.

The Leti-coordinated COSMICC project will combine CMOS electronics and Si-photonics with innovative high-throughput, fibre-attachment techniques. These scalable solutions aim to provide performance improvement an order of magnitude better than current VCSELs transceivers, and the COSMICC-developed technology will address future data-transmission needs with a target cost per bit that traditional wavelength-division multiplexing (WDM) transceivers cannot meet.


Leti cites an example target specification to develop mid-board optical transceivers with data rates up to 2.4 Tb/sec with 200 Gb/sec per fibre using 12 fibres, for a device power metric of less than 2 pJ/bit, at a cost of approximately €0.2/Gb/sec. The project involves 11 partners from five countries.


“By enhancing an R&D photonic integration platform from project member STMicroelectronics, the partners in COSMICC aim to demonstrate the transceivers by 2019,” said project leader Ségolène Olivier of Leti. “We also plan to establish a new value chain that will facilitate rapid adoption of the technologies developed by our members.”


Several technological developments will be used to boost the photonic integration platform’s high data-rate performance, while also reducing power consumption. A first improvement will be the introduction of a SiN layer that will allow development of temperature-insensitive MUX/DEMUX devices for coarse WDM operation. The SiN layer will serve as an intermediate wave-guiding layer for optical input/output to and from the photonic chip.


Additional steps will enhance modulator performance to 50 Gb/sec, while making the transceivers more compact and reducing energy consumption. The partners will also evaluate capacitive modulators, slow-wave depletion modulators with 1D periodicity, and more advanced approaches. These include GeSi electro-absorption modulators with tunable Si composition and photonic crystal electro-refraction modulators to make micrometer-scale devices. In addition, a hybrid III-V on Si laser will be integrated in the SOI/SiN platform in the more advanced transmitter circuits.


In addition to Leti, project participants include STMicroelectronics (France), STMicroelectronics (Italy), University Pavia (Italy), Finisar (Germany), Vario-Optics (Switzerland), Seagate (UK), University of Paris-Sud