The Optical Networks Group (ONG) research is on fundamental properties of light and how it can be used to generate, carry, route and process data for different applications.
Our research focuses on optical communications systems and networks, operating on all time and length scales. These networks underpin the global communications infrastructure and the Internet, and are increasingly being used inside data centres. This helps us understand what is needed to support the increasing broadband data demands of a modern, global society.
Through the study of future optical fibre network architectures and transmission physics, our research and innovations will enable new applications, essential to our digital lives of today.
We are interested in all linear and nonlinear phenomena related to the propagation of optical signals in various media, including different types of fibres and free-space. In particular, we work to maximise optical fibre network capacity, through a combination of new research in nonlinear physics, information theory, machine learning and digital signal processing.
However, the next-generation digital infrastructure needs more than raw capacity – it requires flexible resources and low delays, the ability to allocate capacity when and where it is needed. How to build such intelligent, flexible and secure networks is a major focus of our current research.
Our current research focusses on:
- Adaptive optical networks
- High-speed, ultrawideband optical fibre transmission systems
- Intelligent transceivers
We use a range of digital signal processing algorithms and machine learning techniques to enable the design of future high-capacity, intelligent optical networks, mitigating nonlinearities, reducing complexity and latency for all network operations.
- Transforming networks: TRANSNET
TRANSNET is an EPSRC-funded multidisciplinary research programme aiming to transform the future of optical networks. Commencing in August 2018 and led by UCL, in collaboration with Aston and Cambridge universities, the goal of TRANSNET is to create an adaptive intelligent optical network that is able to dynamically provide capacity where and when it is needed – the backbone of next-generation digital infrastructure.
- Ultra-fast optically interconnected heterogeneous data centers: OptoCloud
OptoCloud, an EPSRC Fellowship awarded to George Zervas, aims to design and build next-generation scalable and sustainable data centres by replacing electronic networks with optical fibre systems. The project explores the fundamental challenges of optical data centres, including optical switching, highly efficient interconnects, network topologies, ultra-fast joint design and control of network and compute resources, while evaluating developed technologies based on industrial use cases.
- Overcoming Resolution and Bandwidth limIT in radio-frequency Signal digitisation: ORBITS
ORBITS is funded by EPSRC and aims to develop novel analogue-to-digital converters (ADCs) using recently-emerged optics and photonics technologies including optical frequency combs, coherent optical processing, and precise optical phase control. Part of the project will look into the application of next-generation ADCs in future-proof high capacity optical and wireless communications to ensure they are capable of supporting information growth into the next decade and beyond.
- Advanced Signal Generation and Detection System for Next-generation Ultra-wideband Communication Networks
This project, funded by EPSRC, aims to transform the development of the information and communication infrastructure by creating an advanced, world-leading signal generation and detection test-bed for advanced communications systems research. The facility will enable UCL and the UK to consolidate and enhance its internationally leading position in communications systems research supporting a wide range of other areas. The project runs from January 2021 to January 2024.
- Beyond Exabit Optical Communications
This project, funded by a UKRI Future Leaders Fellowship awarded to Filipe Ferreira, envisages how to transform emergent spatial division multiplexing (SDM) technology to drive future optical networks by addressing the key issue overlooked by the research community since the introduction of SDM concepts: optical transceivers must undergo >100-fold integration to enable the benefits of multi-mode/core.
We are proud of our previous work and have delivered a number of successful projects that have continuously pushed the boundaries of optical communication research and application. Explore some of our past projects below.
- Unlocking the capacity of optical communications: UNLOC
The UNLOC programme grant, funded by EPSRC, finished in February 2018. The five-year project was a collaboration across the Optical Networks Group, the Aston Institute of Photonic Technologies and multiple industry partners. Combining techniques from information theory, coding, advanced modulation formats, digital signal processing and advanced photonics. UNLOC developed breakthrough techniques to maximise the capacity of optical communication systems.
- Coding for optical communications in the nonlinear regime: COIN
COIN was a collaboration between University College London, Chalmers University of Technology (Sweden), Nokia Bell Labs (Germany) and the University of Toronto in Canada. COIN investigated the application of nonlinear Fourier transforms and nonlinearity-tailored coding and detection to dramatically improve the data throughput of future optical networks. The project, funded by the EU Horizon 2020 programme, ended in 2020.
- Introducing Insight into the Abstraction of Optical Network Infrastructures: INSIGHT
INSIGHT applied a completely different approach to the design of optical communications infrastructure by abstracting optical resources (transmitters, receivers, routers, etc.) to maximise capacity whilst minimising energy and delay, enabling transformational optical fibre applications and services that can be delivered seamlessly. The project was EPSRC funded and finished in 2016.
The Optical Networks Group is home to a state-of-the-art optical communications laboratory, enabling ground-breaking research into adaptive optical networks, high-speed and ultrawideband transmission systems, intelligent transcievers, and more!
Supporting experimental work is our powerful capability for analytical and numerical modelling of fibre signal propagation to predict performance and refine experimental measurements. Discover more about our laboratory resources below.
- Transmission network and test-bed
The transmission and network test-bed is based around an optical fibre recirculating loop and has comprehensive signal generation and detection capabilities. This allows for the characterisation of system performance for wavelength division multiplexed (WDM) systems with advanced modulation formats in conjunction with coherent detection over transmission distances that can simulate real transoceanic scenarios.
Current version digital transmitters include DACs with sampling rates up to 92 GSa/s, capable of generating advanced modulation formats with symbol rates from 6 GBd to 92 GBd. Both direct and coherent detection is used with receiver bandwidth of up to 67 GHz and a range of sophisticated digital signal processing algorithms to compensate for and mitigation of both linear and nonlinear impairments.
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Current capabilities include the generation of polarisation division multiplexed, 64QAM, 256QAM and 1024QAM with probabilistic and geometric shaping of up to 1 Tbit/s across 100 nm of optical bandwidths (approximately 10 THz). To date, experiments over these bandwidths, applying nonlinearity compensation techniques at the transmitter and receiver have helped to achieve record-breaking throughputs.
Research into advanced optical transceivers has included a range of direct-detection techniques, including the Kramers-Kronig receiver, directly-modulated lasers, and digital pre-compensations, in conjunction with subcarrier modulation and low complexity PAM signals. Our current research focuses on intelligent transceivers, enabled by new transceiver design and machine learning algorithms that help transform future optical networks for the cloud.
- Fibre processing and splicing
Our lab is equipped with state-of-the-art fibre processing and splicing facilities that support a wide range of research and collaborations related to special optical fibres. The optical fibre laboratory has the capability of cleaving, tapering, splicing and recoating optical fibres with a diameter from 80 µm to 1.2 mm, which allows us to conduct research on polarisation maintaining, multimode, multi-core fibre, and hollow-core based optical systems.
- Integrated optical devices
In collaboration with academic and industry partners, we have returned to the investigation of optical devices including high-speed semiconductor lasers, integrated silicon transceivers, and optical signal processing methods. A new device test-bed allows for butt and vertical coupling optical signals into integrated optical chips, supporting system verification and innovation in integrated optical devices.
- CONNET and NDFF
The Optical Networks laboratory extends to the CONNECT lab and is a node on the UK National Dark Fibre Facility (NDFF). The CONNECT lab is home to our research on data centre interconnects and novel optical switching; current work focuses on data disaggregation, real-time optical switching and clock and data recovery on nanosecond time scales. The NDFF is an EPSRC National Research Facility, established in 2014 to enable researchers to develop the underpinning communications technologies for the future internet.
We endeavor to ensure that our research provides leadership and impact through its application. Our work underpins many now-deployed commercial systems, leading to huge advances in optical network capacity.
We are proud to be supported by many industry and academic partners. Some of our current collaborations include Microsoft on Optics for the Cloud, Sumitomo on next-generation multi-core fibres, NICT (Japan) on future optical networks, Mitsubishi Electric Research Laboratories (MERL, USA) on advanced modulation and coding, and numerous others, see for example the TRANSNET programme.