Fast Computation of Scattering by Isolated Defects in Periodic Dielectric Media

Posted on 04.05.2021 - 14:55
Scattering by an isolated defect embedded in a dielectric medium periodic in two dimensions, is of interest in many sub-fields of electrodynamics. Present approaches to compute this scattering rely either on the Born approximation and its quasi-analytic extensions, or on \emph{ab-initio} computation that requires large domain sizes to reduce the effects of boundary conditions. The Born approximation and its extensions are limited in scope, while the ab-initio approach suffers from its high numerical cost. In this paper, I introduce a hybrid scheme in which an effective local electric susceptibility tensor of a defect is estimated using a small number of plane wave excitations in domain sizes close to a unit cell. The estimated tensor is embedded into an S-matrix formula based on the reciprocity theorem, which in turn allows the computation of the S-matrix of the defect with only background unit cell field solutions. This scheme reduces the computational cost by almost two orders of magnitude, while sacrificing little in accuracy. I outline the fundamental theory, algorithms and the numerical prescriptions to carry out the computations in high dielectric contrast materials, including metals. I demonstrate the capabilities of this approach with examples from optical inspection of nano-electronic circuitry where the Born approximation fails and the existing methods for its extension are also inapplicable.

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Virk, Kuljit (2021): Fast Computation of Scattering by Isolated Defects in Periodic Dielectric Media. The Optical Society. Collection. https://doi.org/10.6084/m9.figshare.c.5372657.v2
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Journal of the Optical Society of America B

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Kuljit Virk

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