Adaptive optics is widely used in high resolution microscopy to overcome the problems caused by specimen induced aberrations. This is particularly useful when focussing deep into biological specimens, due to the variations in refractive index throughout cells and tissues. Wavefront sensorless adaptive optics (AO) methods (or “sensorless” AO methods, for short) are common as their simple implementation does not include the extra hardware required for a wavefront sensor path. Furthermore, these methods are necessary in microscopes where wavefront sensing is not practical. These sensorless methods perform aberration correction through efficient optimisation of image quality. The wide range of such approaches that have been developed are tailored for different microscopes and applications. We have previously shown that all such methods can be fitted into the same framework, permitting side-by-side evaluation of effectiveness in different imaging scenarios. The parts of this framework include the aberration representation, the optimisation metric (or cost function), and the estimation algorithm. This approach to understanding sensorless AO shows that the seemingly differing methods have many common features. We use this framework to define new approaches that are applicable across a wide range of microscopes. In particular, we examine machine learning approaches to estimation that are independent of the wide range of specimen structures that might be encountered in general application of microscopes. We show how appropriate algorithms can be chosen to enhance the correction range of aberration magnitudes, processing efficiency or accuracy of the sensorless AO microscopes. Furthermore, we show how the methods can be translated across different microscopes. These tools will have broad application across a range of microscope modalities.

Prof Booth is Professor of Engineering Science at the University of Oxford.  His research group is based in the Department of Engineering Science and has many collaborations in other departments across Oxford.  His research involves the development and application of adaptive optical methods in microscopy, laser-based materials processing and biomedical science.  He has held Royal Academy of Engineering and EPSRC Research Fellowships and in 2016 received an Advanced Grant from the European Research Council.   He was appointed Professor of Engineering Science in 2014. In 2012 Prof Booth was awarded the “Young Researcher Award in Optical Technologies” from the Erlangen School of Advanced Optical Technologies at the University of Erlangen-Nürnberg, Germany, and a visiting professorship at the university.  In 2014 he was awarded the International Commission for Optics Prize. He has over 170 publications in peer-reviewed journals, over 25 patents, and has co-founded two spin-off companies, Aurox Ltd and Opsydia Ltd.

Recent progress is subwavelength optics is driven by the physics of Mie resonances excited in high-index dielectric nanoparticles and voids created in dielectric media. This provides a novel platform for localization of light in subwavelength photonic structures and opens new horizons for metamaterial-enabled photonics, or metaphotonics. Recently emerged field of Mie-resonant metaphotonics (also called "Mie-tronics") employs resonances in high-index dielectric nanoparticles and dielectric metasurfaces and aiming for novel applications of the subwavelength optics and photonics. High-index subwavelength resonant dielectric structures emerged recently as a new platform for nanophotonics. They benefit from low material losses and provide a simple way to realize magnetic response which enables efficient flat-optics devices reaching and even outperforming the capabilities of bulk components. In this talk, we aim to review the recent advances in Mie-tronics and photonic bound states in the continuum (BICs) and their applications in metaphotonics and metasurfaces, including enhancement of light-matter interaction for nonlinear and topological metadevices, and the development of active nanophotonic devices and nanolasers. In addition, We predict and demonstrate experimentally the enhancement of circular dichroism for normal propagation of light due to the excitation of multipolar Mie-type modes in silicon resonators and the formation of a complex vectorial field structure. High-quality Mie resonances satisfying optimal coupling condition can lead to giant circular dichroism in the nonlinear regime observed for the generation of the third-harmonic signal by normally propagating circularly polarized fundamental frequency fields.

Yuri Kivshar received PhD degree in 1984 in Kharkov (Ukraine). From 1989 to 1993 he worked at several research centers in USA and Europe, and in 1993 he moved to Australia where he established Nonlinear Physics Center at the Australian National University. His research interests include nonlinear physics, metamaterials, metasurfaces, and nanophotonics. He is Fellow of the Australian Academy of Science since 2002, and also Fellow of Optica (former OSA), APS, SPIE, and IOP. He received many awards for his research including Lyle Medal (Australia), Lebedev Medal (Russia), The State Prize in Science and Technology (Ukraine), Harrie Massey Medal (UK), Humboldt Research Award (Germany), SPIE Mozi Award (USA), and more recently 2022 Max Born Award (Optica).      

It is 10 years since the publication of the seminal SCIENCE paper on the first demonstration of optical fibre communications using OAM modes by Bozinovic et al. This plenary talk will attempt to review the evolution of this particular research strand vis-à-vis the general development of space / mode division multiplexing (SDM/MDM) for the next generation of ultra-high-capacity optical fibre links, covering progress in OAM components and fibres that culminate into increases of 2-3 orders of magnitude in transmission link spectral efficiency, capacity and distance. An appraisal on how OAM modes may play a role in reducing system complexity in such systems will be provided and some thoughts about what would need to be done in future research activities will be shared.

Prof. Siyuan Yu (Fellow of OPTICA) received his Bachelor degree from Tsinghua University in 1984, Master degree from Wuhan Institute of Post and Telecommunications in 1987, and PhD from the University of Glasgow, UK, in 1997. He had been Professor of Photonic Information Systems at the University of Bristol, UK, before joining the School of Electronics and Information Engineering, Sun Yat-sen University, China. Prof. Yu has carried out research in the physics and technologies of photonic integration as well as its application in optical systems and networks for over 35 years, focusing on innovative photonic components technologies aimed at addressing key issues at link and network levels. He contributed to areas such as integrated high-speed optical switches, micro-cavity lasers, all-optical logic circuits and integrated quantum photonics on various materials including III-V semiconductors, silicon nitride, and lithium niobate. In recent years he has worked on developing novel integrated photonic components, optical fibres and systems technologies aimed at harnessing the orbital angular momentum of photons. He has published more than 230 papers, co-edited a book, and has been granted several international patents.

Intelligent photonics is receiving increasingly attention in recent years for its potential applications in optical computing, flexible optical networks, sensing networks and artificial intelligent systems. One key problem for intelligent photonics is how to detect and process the information carried in the optical wave. All-optical switch and large bandwidth photodetector are two key kinds of devices for intelligent photonic systems. In this talk, research progresses on devices and integrated systems for intelligent photonics in our group are reviewed and discussed. Firstly, we construct a PT-symmetric system for low power consumption all-optical switches based on two integrated coupled microcavities. The conversion efficiency at 40 Gbit/s is improved by 100 times, and the pump power is only 1 mW. We also demonstrate photonic crystal optical switches at the rate of 15 Gb/s with power consumption of 948 fJ/bit by introducing FANO microcavity. Secondly, we develop a germanium silicon PIN detector with bandwidth up to 100 GHz and a germanium silicon avalanche photodiode with the gain-bandwidth product up to 620 GHz. Finally, we review our works on intelligent optical systems, including SOA-based integrated chips for digital logic computing, silicon-based matrix-based photonic computing chips, and photodetector-based phased array chips with integrated measurement and communication functions.

Prof. Xinliang Zhang received the Ph.D. degree in physical electronics from Huazhong University of Science and Technology (HUST) in 2001. He is currently with the Wuhan National Laboratory for Optoelectronics, HUST, as a Chair Professor. He is also the president of Xidian University, Xi’an. He has authored or co-authored more than 500 peer-reviewed journal and conference papers. His current research interests are InP-based and Si-based devices and integration for optical network, high-performance computing and optical instrumentation. He is Optica Fellow and COS Fellow.