GT ADG-Systèmes Dynamiques
Exploring Light Scattering by Nanoparticles in the Complex Refractive Index PlaneCédric Blanchard (CEMHTI-CNRS Orléans)
Tuesday 02 December 2025 14:00 - Orléans institut Denis Poisson - Salle de séminaire
Résumé :
Abstract: Understanding how electromagnetic waves interact with a system of particles is crucial, in particular to engineer devices with specific optical properties (e.g. selective absorption or emission as a function of the wavelength). The particles are characterized by their refractive index, which is essentially a complex number. We recently launched a research line in our team which consists of treating light-matter interaction with the tools of complex analysis. By numerically simulating the response of the particles as the refractive index is varied in the complex plane, one can gain valuable insight into the underlying physical mechanisms.
My talk will be divided into two parts:
In the first part, I will focus on the calculation of the poles of the electromagnetic field scattered by a system of particles. I will show how these poles and the associated residues of the field can be used to reconstruct the field for any value of the refractive index. I will also discuss the emergence of an essential singularity at the origin of the complex plane and its physical implications for the response of the particle system when it is excited near such a singularity.
In the second part, I will address homogenization, which aims to extract an effective refractive index for a mixture of particles—i.e., a global refractive index that captures the behavior of the entire system. I will highlight Bergman’s theory, which provides an integral representation of the effective refractive index in terms of a density measure.
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