Professor Philip St.J. Russell, FRS

Director of the Russell Division – Photonic Crystal Fibres

Professor Philip Russell is a founding Director of the Max-Planck Institute for the Science of Light (MPL), which began operations in January 2009. Since 2005 he has also held the Krupp Chair in Experimental Physics at the University of Erlangen-Nuremberg. He obtained his D.Phil. degree in 1979 at the University of Oxford, spending three years as a Research Fellow at Oriel College, Oxford. In 1982 and 1983 he was a Humboldt Fellow at the Technical University Hamburg-Harburg (Germany), and from 1984 to 1986 he worked at the University of Nice (France) and the IBM TJ Watson Research Center in Yorktown Heights, New York. From 1986 to 1996 he was based mainly at the University of Southampton, first of all in the Optical Fibre Group and then in the Optoelectronics Research Centre. From 1996 to 2005 he was professor in the Department of Physics at the University of Bath, where he established the Centre for Photonics and Photonic Materials. His research interests currently focus on scientific applications of photonic crystal fibres and related structures. He is a Fellow of the Royal Society and The Optical Society (OSA) and has won several international awards for his research including the 2000 OSA Joseph Fraunhofer Award/Robert M. Burley Prize, the 2005 Thomas Young Prize of the Institute for Physics (UK), the 2005 Körber Prize for European Science, the 2013 EPS Prize for Research into the Science of Light, the 2014 Berthold Leibinger Zukunftspreis and the 2015 IEEE Photonics Award. He was OSA's President in 2015, the International Year of Light.

2025

Frequency conversion of vortex states by chiral forward Brillouin scattering in twisted photonic crystal fibre

Xinglin Zeng, Philip St.J. Russell, Birgit Stiller

Photonics Research 13 1997-2012 (2025) | Preprint | PDF

Optical vortex states-higher optical modes with helical phase progression and carrying orbital angular momentum-have been explored to increase the flexibility and capacity of optical fibres employed for example in mode-division-multiplexing, optical trapping and multimode imaging. A common requirement in such systems is high fidelity transfer of signals between different frequency bands and modes, which for vortex modes is not so straightforward. Here we report intervortex conversion between backward-propagating circularly polarised vortex modes at one wavelength, using chiral flexural phonons excited by chiral forward stimulated Brillouin scattering at a different wavelength. The experiment is carried out using chiral photonic crystal fibre, which robustly preserves circular polarisation states. The chiral acoustic wave, which has the geometry of a spinning single-spiral corkscrew, provides the orbital angular momentum necessary to conserve angular momentum between the coupled optical vortex modes. The results open up new opportunities for interband optical frequency conversion and the manipulation of vortex states in both classical and quantum regimes.

Velocity-modulated drag-trapping of nanoparticles by moving fringe pattern in hollow-core fiber

Soumya Chakraborty, Gordon Wong, Philip Russell, Nicolas Joly

arXiv 2506.04770 (2025) | Preprint | PDF

We report optical trapping and transport at atmospheric pressure of nanoparticles in a moving interference pattern in hollow-core photonic crystal fiber. Unlike in previous work at low pressure, when the viscous drag forces are weak and the particles travel at the fringe velocity, competition between trapping and drag forces causes the particle velocity to oscillate as it is momentarily captured and accelerated by each passing fringe, followed by release and deceleration by viscous forces. As a result the average particle velocity is lower than the fringe velocity. An analytical model of the resulting motion shows excellent agreement with experiment. We predict that nanoparticles can be trapped at field nodes if the fringes are rocked to and fro sinusoidally-potentially useful for reducing the exposure of sensitive particles to trapping radiation. The high precision of this new technique makes it of interest for example in characterizing nanoparticles, exploring viscous drag forces in different gases and liquids, and temperature sensing.

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