1: He-Ne laser speckle
2: Interference fringes in a soap bubble
3: Fractal electron tree or Lichtenberg figure

About us

We are a theoretical research group forming part of the Photonics Division located at the Blackett Laboratory of Imperial College London. The group is lead by Dr. Matthew R. Foreman who currently holds a Royal Society University Research Fellowship.

Our research focuses on optical and plasmonic sensing, polarisation sensitive imaging, disordered media and electromagnetic theory. More information on some of our past and present projects can be found by visiting our Research pages.

Recent news

Photon 22

30 Aug 2022: Photon22, held in Nottingham this year, was an interesting and diverse conference, drawing together many experts on sensing and polarization optics from around the UK and beyond. We were there presenting our work on single particle plasmonic sensing.

Complex Nanophotonics Science Camp

3 Aug 2022: Niall presented his poster on modelling polarised light scattering in disordered media with a random matrix approach at the 2022 Complex Nanophotonics Science Camp. Thanks to all for their interest and questions.

London Plasmonics Forum

8 Jun 2022: The London Plasmonics Forum was held at Imperial College this year. There was a diverse range of talks. Matthew was there presenting a poster on our recent single particle plasmonic sensing work. It was good to catch up with some old colleagues and meet some new ones.

Recent publications

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N. Byrnes and M. R. Foreman, "Random matrix theory of polarized light scattering in disordered media" arXiv , 2205.09423 (2022).

Abstract : In this work we present a method for generating random matrices describing electromagnetic scattering from disordered media containing dielectric particles with prescribed single particle scattering characteristics. Resulting scattering matrices automatically satisfy the physical constraints of unitarity, reciprocity and time reversal, whilst also incorporating the polarization properties of electromagnetic waves and scattering anisotropy. Our technique therefore enables statistical study of a variety of polarization phenomena, including depolarization rates and polarization-dependent scattering by chiral particles. In this vein, we perform numerical simulations for media containing isotropic and chiral spherical particles of different sizes for thicknesses ranging from the single to multiple scattering regime and discuss our results, drawing comparisons to established theory.

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H. Lee, J. Berk, A. Webster, D. Kim and M. R. Foreman, "Label-free detection of single nanoparticles with disordered nanoisland surface plasmon sensor" Nanotechnology 33, 165502 (2022).

Abstract : We report sensing of single nanoparticles using disordered metallic nanoisland substrates supporting surface plasmon polaritons (SPPs). Speckle patterns arising from leakage radiation of elastically scattered SPPs provides a unique fingerprint of the scattering microstructure at the sensor surface. Experimental measurements of the speckle decorrelation are presented and shown to enable detection of sorption of individual gold nanoparticles and polystyrene beads. Our approach is verified through bright-field and fluorescence imaging of particles adhering to the nanoisland substrate.

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N. Byrnes and M. R. Foreman, "Polarisation statistics of vector scattering matrices from the circular orthogonal ensemble" Opt. Commun. 503, 127462 (2022).

Abstract : We study the polarisation properties of random N × N scattering matrices distributed according to the circular orthogonal ensemble. We interpret 2 × 2 sub-blocks of the scattering matrix as Jones matrices and study their statistical properties. Using the polar decomposition, we derive probability density functions for retardance and diattenuation from scattering matrices of arbitrary size and in the limit N → ∞.

Funding

Our research is supported by generous funding from:

The Royal Society
Microsoft Research
EPSRC