Abstract
We investigate the T-matrix approach for the simulation of light scattering by an oblate particle near a planar interface. Its validity has been in question if the interface intersects the particle's circumscribing sphere, where the spherical wave expansion of the scattered field can diverge. However, the plane wave expansion of the scattered field converges everywhere below the particle, and in particular at the planar interface. We demonstrate that the particle-interface scattering interaction is correctly accounted for through a plane wave expansion in combination with Fresnel reflection at the planar interface. We present an in-depth analysis of the involved convergence mechanisms, which are governed by the transformation properties between spherical and plane waves. The method is illustrated with the cases of spherical and oblate spheroidal nanoparticles near a perfectly conducting interface, and its accuracy is demonstrated for different scatterer arrangements and materials.
Highlights
Many applications in nano optics rely on the interaction of light with wavelength scale particles near planar surfaces, for example plasmonic structures supported by a substrate [1], or scattering layers for light management in optoelectronic thin film devices, such as organic light emitting diodes [2, 3]
We investigate the T-matrix approach for the simulation of light scattering by an oblate particle near a planar interface
We demonstrate that the particle-interface scattering interaction is correctly accounted for through a plane wave expansion in combination with Fresnel reflection at the planar interface
Summary
Many applications in nano optics rely on the interaction of light with wavelength scale particles near planar surfaces, for example plasmonic structures supported by a substrate [1], or scattering layers for light management in optoelectronic thin film devices, such as organic light emitting diodes [2, 3]. The SWE may not converge everywhere on the planar surface [12], which puts the general validity of the T-matrix approach for such systems into question This apparent restriction might be one reason why, despite its numerous benefits [5], the T-matrix formalism is not employed more frequently in application-oriented studies of light scattering by photonic structures near interfaces. The objective of the present paper is to demonstrate that the scattered field can be accurately computed using the T-matrix formalism - even if the circumscribing sphere and the planar surface intersect - thereby paving the way for a wider use of that method in the modelling of photonic structures supported by a substrate. We use the term "oblate particle" in the broadest possible sense for all objects that extend further into the lateral directions than into the direction orthogonal to the planar surface
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