Photonic Systems for next generation satellites

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.

Satellite technologies are an integral part of our everyday life. We all rely on communication satellites to obtain live streams of television, radio and telephone signals. Earth observation satellites provide us with information about our planet's physical, chemical and biological systems, data which is essential for meteorologists, environmentalists and policy-makers. Navigation satellites form the backbone of our emergency, marine, aviation and logistics systems. All these services have a tangible, positive impact on the whole of our society. The satellites enabling these services rely upon the communication modules which this project is aiming to innovate by using integrated photonics in place of conventional RF components. This will lead to an increased capacity and improved performance of next-generation satellites.
There are currently hundreds of communication satellites in operation, providing mobile and fixed (point-to-point-communication) services to billions of people worldwide. The development of most of these satellites has been driven by the commercial sector. The UK space industry is one of the biggest developers and exporters of communication and scientific satellites, and underpins many parts of the British economy, currently contributing over £11.8 billion thereto and directly employing over 35,000 people. The space sector is growing very quickly while remaining particularly dynamic and highly competitive. To maintain the UK's strategic leading position as one of the biggest producers of commercial communication satellites in Europe, innovative solutions such as the proposed photonic-based Frequency Generation Unit must be provided quickly. The novel photonic integrated communications payloads that will be developed through this project will have great potential to expedite the development of next-generation satellites by making them much smaller and, therefore, highly cost-effective. In the longer term, it will result in lowering the cost of satellite-delivered data, allowing for the creation of satellite-enabled networks (clusters of small satellites) that can bring digital opportunities in the most inclusive way to everyone, regardless of their location.