Collaboration at Leti to advance silicon photonics beyond 1Tb/s
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 (France), University of St. Andrews (UK), University of Southampton (UK) and Ayming (France).
The conceptual illustration above shows a schematic of a COSMICC on-board optical transceiver at 2.4 Tb/sec (50 Gbpsec/wavelength, 4 CWDM wavelengths per fibre, 12 fibres for transmission, 12 fibres for reception.
As one of three advanced-research institutes within the CEA Technological Research Division, Leti serves as a bridge between basic research and production of micro- and nanotechnologies. It is committed to creating innovation and transferring it to industry. Backed by its portfolio of 2,800 patents, Leti partners with large industrials, SMEs and startups to tailor advanced solutions that strengthen their competitive positions. It has launched 59 startups. Its 8,500m² of new-generation cleanroom space feature 200 mm and 300 mm wafer processing of micro and nano solutions for applications ranging from space to smart devices; www.leti.fr