A domain decomposition method for computing the scattering matrix of waveguide circuits

Fuente: arXiv
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Main Authors: Goodwill, Tristan, Jiang, Shidong, Rachh, Manas, Sugita, Kosuke
Format: Preprint
Published: 2025
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author Goodwill, Tristan
Jiang, Shidong
Rachh, Manas
Sugita, Kosuke
author_facet Goodwill, Tristan
Jiang, Shidong
Rachh, Manas
Sugita, Kosuke
contents We analyze and develop numerical methods for time-harmonic wave scattering in metallic waveguide structures of infinite extent. We show that radiation boundary conditions formulated via projectors onto outgoing modes determine the coefficients of propagating modes uniquely, even when the structure supports trapped modes. Building on this, we introduce a fast divide-and-conquer solver that constructs solution operators on subdomains as impedance-to-impedance maps and couples them by enforcing continuity conditions across their interfaces. For Dirichlet waveguides, the computation of impedance-to-impedance maps requires the solution of mixed Dirichlet-Impedance boundary value problems. We construct a second-kind Fredholm integral equation that avoids near-hypersingular operators, requiring only integral operators whose kernels are at most weakly singular. Numerical experiments on large structures with many circuit elements demonstrate substantial efficiency gains: the proposed approach typically outperforms state-of-the-art fast iterative and fast direct solvers by one to two orders of magnitude.
format Preprint
id arxiv_https___arxiv_org_abs_2509_20695
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A domain decomposition method for computing the scattering matrix of waveguide circuits
Goodwill, Tristan
Jiang, Shidong
Rachh, Manas
Sugita, Kosuke
Numerical Analysis
Optics
31A10, 35Q61, 45B05, 65R20, 65F55
We analyze and develop numerical methods for time-harmonic wave scattering in metallic waveguide structures of infinite extent. We show that radiation boundary conditions formulated via projectors onto outgoing modes determine the coefficients of propagating modes uniquely, even when the structure supports trapped modes. Building on this, we introduce a fast divide-and-conquer solver that constructs solution operators on subdomains as impedance-to-impedance maps and couples them by enforcing continuity conditions across their interfaces. For Dirichlet waveguides, the computation of impedance-to-impedance maps requires the solution of mixed Dirichlet-Impedance boundary value problems. We construct a second-kind Fredholm integral equation that avoids near-hypersingular operators, requiring only integral operators whose kernels are at most weakly singular. Numerical experiments on large structures with many circuit elements demonstrate substantial efficiency gains: the proposed approach typically outperforms state-of-the-art fast iterative and fast direct solvers by one to two orders of magnitude.
title A domain decomposition method for computing the scattering matrix of waveguide circuits
topic Numerical Analysis
Optics
31A10, 35Q61, 45B05, 65R20, 65F55
url https://arxiv.org/abs/2509.20695