2022-01-05 11:00:00

Thomas Krauss University of York

Beyond Q: The importance of the amplitude for nanophotonic resonances

Nanophotonic resonances have seen a sustained interest because of their ability to enhance light-matter interactions, with recent developments such as metasurfaces and bound states in the continuum (BIC) adding interest to the topic. Researchers typically aim to maximise the Q-factor as a measure for the interaction; this is true for both light emission, where Q/V (V: Volume) is the key parameter, but also for sensing, where QxS (S: Sensitivity) is the usual figure of merit. Here, we show that this picture can be overly simplistic and that it is essential to take losses and the resonance amplitude into account. Using sensors as an example, we present an ab-initio model and show that the performance is not optimised by simply maximising the Q, but by counterbalancing Q and amplitude. We compare different structures in light of this model and demonstrate high-sensitivity biological measurements with structures that achieve moderate Q but high resonance amplitude.  

Speaker's Bio

Prof Krauss achieved his first degree (“Diplom-Ingenieur”) in Cologne, Germany (1989), followed by a PhD in Electrical Engineering at Glasgow, UK 1992 on the topic of semiconductor ring lasers. He initiated the work on photonic crystals in the UK in 1993, a research field where he made pioneering contributions worldwide, spent a year at Caltech, Pasadena, CA in 1997 and became Professor of Physics at St Andrews, UK in 2000. He moved to the University of York, UK in 2012 to focus on light-matter interaction with biological systems, where he was also Strategy Champion “Technologies for the Future" 2015-2019. He has led major EU and UK research projects and currently holds a substantial research portfolio related to optical biosensors funded by EPSRC, the Wellcome Trust, and well supported by industry partners. His papers are well cited (h=90) and he is a Fellow of the Royal Society of Edinburgh, the Institute of Physics and the Optical Society. He was one of the founding editors of OSA's flagship journal Optica in 2014 and became its Deputy Editor in early 2020.