Space technologies, data and services have become indispensable in our everyday lives. Communications satellites (COMSATs), alongside optical fibre, are the main means of global data transmission. In fact, for a vast number of users, such as marine and airways fleets, autonomous cars, remotely located aid camps, and hospitals and schools in less developed areas, satellite communication is the only way to broadcast, navigate or access broadband services. Earth observation satellites provide immediate information in the event of natural disasters, and allow better coordination of emergency and rescue teams. Satellite-based technologies help increase the efficiency of fisheries and agriculture, and play an important role in transport by controlling air and maritime traffic. Both COMSAT and surveying services are critically dependent on the communication links between satellites in orbit and ground control stations. Increasing data capacity of these links and allowing frequency flexibility, which cannot be easily provided by established RF solutions, is long overdue. It is clear that industry needs a step change in technology.
Against this backdrop, the project focuses on using key advances in photonic integrated solutions to revolutionise satellite payloads (modules). An integrated photonics approach allows for several optoelectronic functionalities (lasers, photodiodes, etc.) to be monolithically integrated on a single chip. Such integration improves robustness, reduces losses between individual devices and, most importantly, offers ease of scalability, low mass and small footprint, creating great prospects to reduce the cost of satellites.
Through close collaboration with academic and industrial partners, this project will develop the world's first integrated, broadly tuneable, photonic-based Frequency Generation Unit (FGU) which can be the heart of satellite communication payloads. The advantage of a photonic FGU over the conventional RF-based solution comes from the great frequency agility of the photonic system, which will allow for the FGU to be included both in communication and earth observation satellites. Firstly, the FGU will form part of innovative communication payloads in communication satellites (transponders), allowing for high-throughput data links from satellites to ground stations and, in the future, between satellites. Furthermore, the FGU will also be deployed in earth observation satellites, allowing for reference-signal distribution inside the satellite using a flexible, lightweight optical fibre rather than a conventional coaxial cable. The use of a photonic FGU would dramatically reduce the weight of a satellite, eliminating the need for tens to hundreds of kilograms of coaxial cables (depending on satellite type), and make a significant monetary saving, given the cost of launching into orbit of $25,000/kg. Secondly, a novel architecture for a complete communications payload based almost entirely on photonics is going to be investigated. Replacing conventional RF components with integrated photonic sub-systems will result in an unprecedented mass and volume reduction, which, in turn, will lead to a reduction in the cost of in-orbit-delivered data capacity.
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