Research and Facilities
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.
Current Projects
Past Projects
Experimental Facilities
Collaborations
Current Projects
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.
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.
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.
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.
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.
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.
Past Projects
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.
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.
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.
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.
Experimental Facilities
The Optical Networks Group (ONG) is home to a state-of-the-art optical communications laboratory, enabling ground-breaking research into adaptive optical networks, high-speed and ultra-wideband transmission systems, intelligent transceivers, and next-generation fibre technologies!
Supporting experimental work is our powerful capability for analytical and numerical modelling of fibre signal propagation to predict performance and refine experimental measurements. Explore our key laboratory resources below:
Transmission network and test-bed
At the core of our experimental infrastructure is a fully programmable optical transmission testbed, centred around a high-speed optical transceiver with comprehensive signal generation and detection capabilities and a recirculating fibre loop for long-haul transmission study. This allows for the characterisation of system performance for wavelength-division multiplexed (WDM) systems with advanced modulation formats in conjunction with coherent detection, supporting simulated transmission over transoceanic distances.
Current version digital transmitters include a state-of-the-art DAC with sampling rate up to 256 GSa/s and >80 GHz bandwidth TFLN DP-IQ modulator, capable of generating high-speed advanced modulation format dual-polarisation signal. Multiple 92 GSa/s DACs together with 35 GHz DP-IQ modulators can operate in the O-, S-, C-, L-bands, generating odd-even WDM channels. Our coherent detection systems support receiver bandwidths up to 110 GHz, combined with sophisticated digital signal processing (DSP) techniques for the mitigation of linear and nonlinear transmission impairments.
The recirculating fibre loop supports ultra-wideband operation and is capable of simulating WDM transmission over thousands of kilometres, enabling the investigation of nonlinear interference, ASE noise characterisations, ISRS effects over long distances.
Capabilities
Our current setup supports:
- Polarisation-division multiplexed (PDM) 64 QAM, 256 QAM, 1024 QAM and higher
- Probabilistic and geometric constellation shaping
- Transmission of signals up to 1 Tbit/s per WDM channel over 130 nm (approximately 18 THz) of optical bandwidth, covering S-, C-, L-bands
- Coherent O-band transmission with advanced Bismuth-doped fibre amplifier (BDFA)
To date, experiments over these bandwidths, applying Raman amplification and nonlinearity compensation techniques at the transmitter and receiver, have helped to achieve record-breaking throughputs in unrepeated link and long-haul transmission.
Intelligent Optical Transceivers
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 coherent 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 cutting-edge fibre processing tools, enabling cleaving, tapering, splicing, and recoating of optical fibres with a diameter from 80 µm to 1.2 mm. This supports a wide range of research activities involving polarisation maintaining, multimode, multi-core fibre, and hollow-core fibre based optical systems.
Integrated optical devices, data centre interconnects and quantum internet
In collaboration with academic and industry partners, we are developing and testing a new generation of integrated optical devices including high-speed semiconductor lasers, integrated transceivers, and optical signal processing platforms. A device test-bed allows for edge- and vertical-coupling optical signals into photonic integrated circuits (PICs), supporting system verification and innovation in integrated optical devices. The material platforms explored for photonic integration include silicon, silicon nitride, lithium niobate on insulator and III/V. One of the key research directions is also 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 as well as applications for quantum communications and quantum internet.
ICCS and NDFF
UCL is node in the UK National Dark Fibre Facility (NDFF). The NDFF is an EPSRC National Research Facility established in 2014, enabling full-scale experimentation using live and dark fibre links, supporting cutting-edge research in high-capacity and long-haul communications. The dark fibre network can be integrated with the ONG recirculating loop to enable a much longer installed fibre transmission and networking experiments. There is also a connection to JOINER; a university-led national experimentation platform created to accelerate future communications and networks research, exploitation and adoption. It brings together the knowledge and research capabilities of 11 world-leading universities and labs from across the UK to offer a combination of test environments, tools and infrastructure, combined with an emphasis on knowledge sharing, dissemination and skills development.
UCL Institute of Communications and Connected Systems (ICCS) has developed a state-of-the-art millimetre-wave transmission test bed, with capability of covering V (50-75GHz), W (75-110GHz) and D (110-170GHz) bands. The key research directions include high-capacity millimetre-wave transmission, low noise carrier generation, orthogonal frequency-division multiplexing signal design and antenna characterisation. The ICCS system features ultra-high capacity wireless transmission testbed, device and signal characterisation facilities covering 1-220GHz.
Collaborations
We are committed to research that delivers real-world impact. Our work underpins many commercially deployed optical systems, and we actively collaborate with both academic and industrial partners to address future challenges in global communications. Some of our current collaborations include Microsoft on Optics for the Cloud, Sumitomo on next-generation multi-core fibres, Sumitomo Osaka Cement on high-speed optical transmitter, KDDI (Japan) and NICT (Japan) on ultra-wideband transmission and future optical networks, Coherent on optical processor solutions, Mitsubishi Electric Research Laboratories (MERL, USA) on advanced modulation and coding, and numerous others, see for example the TRANSNET programme. and We have been collaborating with Corning Inc for over 30 years on the development of new optical fibres and their applications in different system and network configurations. Recent collaborations & support include OFS/Lightera.
