“…The FMM technique is currently considered as one of the most efficient and accurate electromagnetic analysis frameworks for optics and photonics, in terms of allowing general structure modulation, oblique incidence, and analysis of sharp resonance, as required in this paper. We have relied on our previous profound experience with both periodic (1D and 2D cases) and aperiodic (i.e., isolated structures-for 2D and 3D cases) versions of the FMM technique, with several important technical extensions, such as proper Fourier factorization, adaptive spatial resolution [23], the normal vector method, symmetrization techniques, and recently also non-locality [24], applied extensively to various rather complex problems, including, e.g., high-Q optical nanocavities [25], plasmonic gratings, metasurfaces, and waveguides [26], plasmonic sensor structures [27], magneto-optic structures [28], periodic arrays exhibiting the EOT effects [29,30], bound modes in the continuum [29], or graphene plasmons [30,31].…”