Grand Séminaire d'Institut

Vendredi 27 Novembre 2020 à 11h00.

Recent developments in the electromagnetic modelling of complex nanostructures

''Recent developments in the electromagnetic modelling of complex nanostructures
Kevin Vynck, LP2N, CNRS - Institut d'Optique Graduate School - Univ. Bordeaux, France.
Ongoing mobility to ILM.

Complex nanostructures are found in many branches of science and technology, from finely-engineered nanoresonators in photonic components, to self-assembled colloidal structures in soft matter, to cellular aggregates in biological tissues, to particle suspensions in the atmosphere. Unfortunately, modelling the interaction of light with such systems is often computationally heavy and provides little physical insight.
In this seminar, I will present some of the outcomes of our recent efforts to mitigate these limitations. In a first part, I will introduce a numerical method based on the concept of quasinormal modes (QNMs) [1] to analyze and design the scattering properties of individual elements like plasmonic nanoantennas or dielectric particles [2]. QNMs are the natural resonances of open (non-Hermitian) systems. Their study has bloomed in recent years, enabling a more insightful and efficient modelling of various problems in photonics and plasmonics. In a second part, I will introduce a novel numerical method, named ``Global Polarizability Matrix'' (GPM) method, that enables a very efficient modelling of large ensembles of complex (non-spherical) particles incorporated in stratified media [3,4]. The GPM method requires a remarkably low memory usage compared to Maxwell's equations solvers like finite elements or finite differences methods. It can also handle situations in which the scattering elements are touching or even crossing planar interfaces, unlike the popular T-matrix and null-field methods [5,6], thereby opening new perspectives in the study of complex optical nanostructures.
References
[1] P. Lalanne, W. Yan, K. Vynck, C. Sauvan, and J.-P. Hugonin, Laser Photon. Rev. 12, 1700113 (2018).
[2] T. Wu, A. Baron, P. Lalanne, and K. Vynck, Phys. Rev. A 101, 011803(R) (2020).
[3] M. Bertrand, A. Devilez, J.-P. Hugonin, P. Lalanne, and K. Vynck, J. Opt. Soc. Am. A 37, 70-83 (2020).
[4] M. Bertrand, J.-P. Hugonin, P. Lalanne, and K. Vynck, in preparation.
[5] M. I. Mishchenko, J. W. Hovenier, and L. D. Travis, "Light scattering by nonspherical particles: theory, measurements, and applications" (IOP, 2000)
[6] A. Doicu, T. Wriedt, and Y. A. Eremin, "Light scattering by systems of particles: null-field method with discrete sources: theory and programs" (Springer, 2006).
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