Model order reduction of layered waveguides via rational Krylov fitting

Abstract Rational approximation recently emerged as an efficient numerical tool for the solution of exterior wave propagation problems. Currently, this technique is limited to media which are invariant along main direction. We propose a new model order reduction-based approach compressing unbounded waveguides with layered inclusions. It based on nonlinear rational least squares problem using RKFIT method. show that approximants can be converted into accurate finite difference representation within Krylov framework. Numerical experiments indicate computes more grids than previous analytic approaches and even works in presence pronounced scattering resonances. Spectral adaptation effects allow dimensions near or below Nyquist limit.