11:00 – 11.30
Hollow core optical fibres – a British invention with revolutionary potential

Francesco Poletti, Optoelectronics Research Centre, University of Southampton

Hollow Core Fibres were invented in the 1990s by UK scientists who merged the concepts of photonic crystals and optical fibres. By guiding light in air, they promised the ultimate performance in a flexible waveguide: better loss, nonlinearity, speed and ultimately information throughput than conventional glass-guiding fibres. For two decades however, losses remained too high for this technology to really make an impact in the application where solid core fibres really excel: long distance optical communications. In the last 5 years, rapid progress led once again by academic and industrial British efforts, has brought their loss close to and in some cases better than the fundamental limit of glass fibres. This presentation will highlight the latest results and some of the applications that might be empowered by further progress in this area, and make the case for the creation of a UK ecosystem to benefit from this nascent technology.

11:30 – 12:00
Cost-effective FSO: Challenges and Opportunities
Gerald Bonner, Senior Researcher, Fraunhofer Centre for Applied Photonics

Free-space optical communications (FSOC) are becoming increasingly important for various use cases, as demand for bandwidth and competition for the limited RF spectrum increase. FSOC also offers greater security than RF comms, and more flexible deployment than fibre-based optical comms. However, the alignment and pointing stability of the free-space optics (FSO) system presents substantial challenges, as do environmental factors such as atmospheric turbulence. Background light can also pose problems, creating a complex parameter space and trade-offs between optical design, alignment tolerances, and performance. Active beam-steering systems can correct for misalignment and turbulence, but such systems are often prohibitively expensive, limiting wide-scale deployment of FSOC. This presentation will review these challenges, current technical solutions, and ongoing challenges and opportunities for the future.

12:00 – 12:15
Characterisation of low loss hollow core optical fibres
Prof. Radan Slavík, Head of Coherent Optical Signals group, Optoelectronics Research Centre (ORC), University of Southampton

Hollow Core optical fibres (HCFs) have superior performance over standard glass-core  fibres (such as SMF) in almost every metric. This is thanks to the almost complete elimination of light-glass interaction in HCFs. This includes low nonlinearity achieved simultaneously with low chromatic dispersion, low propagation latency, low sensitivity of latency to temperature variations, etc. Further, their attenuation recently reached below that of  SMFs at wavelengths <1300 nm, with the lowest attenuation reported of 0.22 dB/km.

Backscattering in HCFs is 30-45 dB lower than in SMFs, representing simultaneously an advantage and a challenge, as this makes the distributed characterization of HCFs challenging.  Such characterization is needed for fabrication process optimization and control, for fault-finding in installed fibres, and for distributed sensors. We will discuss how OTDR and OFDR techniques can be used with HCFs. We will also discuss means to accurately measure low values of HCF attenuation using relatively short HCF samples.

12:45 – 13:00
Environmental Sensing with Structured Light
Martin P J Lavery, Professor and leader of the Structured Photonics Research Group, University of Glasgow

The propagation of structured light in the turbulent channels has attracted considerable attention recently due to its potential applications in free-space optical (FSO) communication systems. Atmospheric turbulence induces variation in refractive index arising from local changes in temperature, wind speed and pressure, that distort free-space propagating optical. We will present a machine learning assisted environmental sensing approach that utilizes the unique distortions of OAM modes that have propagated over an experimental channel with controllable atmospheric turbulence to predict the changes in windspeed and temperature with single measurement accuracy of 74% and sequential measurement accuracy of 99.6% for 12 seconds of repeated measurements. A system that can decipher these complex interactions at high speed to sense changes in weather conditions based on the optical interaction could be transformative for adaptive communication systems with dynamic coding, temperature monitoring in extreme environments where radio-doppler systems cannot be deployed, such as jet engine exhausts.

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