This project addresses the problems of high bandwidth satellite payload routing. With the ever-increasing demand on throughput, an all optical switching fabric has been architected, capable of transmitting >2Tbps. The preferred optical architecture utilises fast wavelength-switched tunable lasers for implementing high bandwidth switching capability across passive optical backplane. An optical switch breadboard has been designed to demonstrate the performance. Compared with current state-of-the-art processors, it is expected to display lower power consumption, lower mass, higher scalability and lower blocking of the processor.
The objective of this project was to design and develop an optical switch breadboard to showcase an all-optical, non-blocking switching network. The project concentrated on the delta technology development of the critical optical components to enable high-throughput and ultra-fast switching of hundreds of incoming/outgoing beams. The key optical performance requirements were >6.72 Gbps throughput and <37.5ns optical reconfiguration time. In addition, the breadboard also needed to demonstrate scalability to >100 beams (up to 200 beams) in terms of mass, size and power consumption.
The key challenges to the project were:
- To develop tunable lasers capable of fast switching while conforming to size, weight and power requirements. Syntune focussed on a laser design that could meet the challenging environmental conditions of a satellite, while Tyndall focussed on developing a new tunable laser design capable of faster-switching and potentially reduced power consumption.
- To achieve optical reconfiguration in <37.5 ns. This required careful control and timing of the tunable lasers. Reconfiguration in 40ns was successfully demonstrated on the Syntune devices using a dual-laser pipelining scheme.
As described in the statement of work, “The implementation of … a transparent processor for future meshed-type repeaters could greatly boost the satellite throughput, with respect to a full regenerative processor approach.” An all-optical switching architecture has been designed in this project based on passive wavelength routing. The key delta technologies of this architecture are fast tunable lasers and fast burst-mode receivers. Two tunable laser designs have been developed and fast switching has been proven.
Three optical architectures have been evaluated, concentrating on fast reconfiguration of the transmitter, receiver or optical switch fabric. The delta technology work was done in conjunction with three partners. Syntune and Tyndall developed tunable laser technology capable of switching in <45ns, while Lionix focussed on their tunable microring technology. Intune Networks, the project prime, developed the calibration and control of the tunable lasers as well as an ultra-fast burst-mode receiver.
Ultimately, the tunable laser solution was the most technologically advanced and so the optical breadboard was designed witih this solution. The figure shows the non-blocking passive wavelength routing architecture. It is based on using tunable transmitters, which are then routed to burst-mode receivers via a MxM AWG. By using a combination of MxM and 1xN cyclic AWGs, the architecture is non-blocking and routing is dependent solely on the transmitter wavelength.
- Consolidation of the optical switch architecture,
- Preliminary design of the optical switch,
- Critical component development and detailed design of the optical switch breadboard,
- Concurrent (by each contractor) manufacturing design and delta-technology development of critical optical components and functional modules,
- Detailed manufacture and design of the optical switch breadboard,
- Procurement, manufacturing, assembly and integration of the optical switch breadboard,
- Verification and test campaign of the optical switch breadboard,
- Critical appraisal, recommendations and technology development roadmap.
The project has been completed. Syntune and Tyndall delivered tunable laser devices capable of switching in <40ns. Tyndall’s laser is based on a much less mature technology, and the prototypes proved the tunability and fast-switching capabilities of the device. Syntune’s laser is a mature product, and was able to meet the optical requirements. Syntune were also able to address the scalability issues particularly in terms of power consumption over temperature. Fast-switching control was demonstrated by Intune and the design of the burst-mode receiver and optical breadboard are complete.