News: Optoelectronics
17 May 2024
ESA awards €0.5m to Phlux, Airbus and Sheffield University to develop free-space optics satellite terminals
Sheffield University spin-off Phlux Technology (which designs and manufactures 1550nm avalanche photodiode infrared sensors), Airbus Defence and Space, and The University of Sheffield have embarked on a €500,000 project to build more efficient free-space optical communications (FSOC) satellite terminals.
Funded by the European Space Agency (ESA) in a first phase that runs until the end of September 2025, the project’s medium-term goal is to achieve reliable 2.5Gbps communications with low Earth orbit (LEO) satellites at 1550nm wavelength. These satellites orbit the earth at heights of up to 2000km (1200 miles). A longer-term aim is to produce links that will operate at 10Gbps.
Phlux Noiseless InGaAs avalanche photodiodes (APDs) are used as infrared sensors in FSOC receivers and are expected to deliver 6dBm more sensitivity than traditional indium gallium arsenide APDs operating at 1550nm. This means that they can detect much lower signal levels, enabling faster and higher-bandwidth links with low latency to be developed. Also, adequate performance can be maintained for longer periods because link integrity is maintained over a wider angle as the satellite passes overhead.
A key technical challenge with realising FSOC is that the infrared signals used to transmit data are diffracted as they pass through the troposphere (the atmospheric layer closest to Earth). Variations in our atmosphere’s air temperature, humidity and turbulence cause fluctuations in the intensity and angle of incidence of the infrared signal. This makes the beam wander over the signal detector area, limiting performance. This issue is being addressed by developing a large-area, high-sensitivity APD to produce a wider receptor.
A radiation-hard detector module being developed in this project has other potential applications including space debris monitoring, greenhouse gas detection, and space navigation.
“This project is an endorsement of the value of our patented APD technology developed at The University of Sheffield,” says Phlux’s CEO Ben White. “With more than an order-of-magnitude improvement in sensitivity over traditional devices, we offer the enabling component that makes other technology breakthroughs possible. Higher-performance FSOC links are a perfect example,” he adds.
“The availability of APD products at 1550nm for optical communication with sensitivities close to those of fibered low-noise optical amplifiers could be a game changer for the development of cost-effective laser terminals and optical ground-stations,” comments Ludovic Blarre, who is leading Airbus Space Systems’ optical communication roadmap. “This will be an enabler for the rapid development of optical communication in satellites for direct-to-earth applications and inter-satellite links with data rates below 10Gbps. Our team is delighted to work with Phlux Technology and the University of Sheffield towards this goal and to carry out irradiation tests on their patented APD technology,” he adds.
“This is a very challenging and exciting project that will provide opportunities for our team to extend our patented technology to an exciting new application in FSOC,” says professor Chee Hing Tan of the University of Sheffield. “Working with ESA, we hope to provide a disruptive technology that will accelerate the adoption of satellite-to-ground FSOC.”
As demand for bandwidth grows beyond the capabilities of radio frequency systems, the FSOC market will rise at a compound annual growth rate (CAGR) of 31.3% to $4.8bn by 2031, forecasts analyst firm Allied Market Research.
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