Quasi-normal mode theory of the scattering matrix, enforcing fundamental constraints for truncated expansions

Benzaouia, Mohammed; Joannopoulos, John D.; Johnson, Steven G.; Karalis, Aristeidis

doi:10.1103/physrevresearch.3.033228

Cited by 22 publications

(18 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…On the other hand, the current coupled-mode formalism does not work well for resonance modes that are not well isolated. To accurately include the effects of all resonance modes supported by a resonator, it is necessary to introduce quasi-normal modes to the coupled-mode formalism. , Meanwhile, plane-wave channels do not describe the near field around the metasurface. More complex basis for the channels in the coupled-mode formalism are required to achieve inverse design of near field …”

Section: Discussionmentioning

confidence: 99%

Inverse Design of Metasurfaces Based on Coupled-Mode Theory and Adjoint Optimization

et al. 2021

View full text Add to dashboard Cite

Metasurfaces typically have sizes much larger than the wavelength yet contain a large number of subwavelength features. Thus, it is difficult to design entire metasurfaces using full-wave simulations. However, without full-wave simulations, most existing design approaches cannot accurately model the interactions between the individual elements comprising the metasurface. Here, we demonstrate an approach for the design of resonant metasurfaces based on coupled-mode theory. Our approach fully describes wave dynamics and coupling in metasurfaces and is much more computationally efficient than full-wave simulations. As an example, we show that the combination of coupled-mode theory and adjoint optimization can be used for the inverse design of high-numerical-aperture (0.9) metalenses with sizes as large as 10000 wavelengths. The computation efficiency of our approach is orders of magnitude faster than full-wave simulations. Complex functionalities such as angle-multiplexed metasurface holograms can also be realized. With its accuracy and efficiency, the proposed framework can be a powerful design tool for large-scale resonant flat-optics devices.

show abstract

Section: Discussionmentioning

confidence: 99%

Inverse Design of Metasurfaces Based on Coupled-Mode Theory and Adjoint Optimization

et al. 2021

View full text Add to dashboard Cite

show abstract

“…This is because the largest contributions come from terms where β 0;m,k (z) is smallest due to the integral over the phase in Eq. (36). In this case, β 0;m,k (z) may be smallest when k = −1, 0, or 1 depending on the propagation directions of the incident wave and guided mode (if both propagate in the same direction, it is when k = 0).…”

Section: Validationmentioning

confidence: 98%

“…II C, for a particular instantaneous waveguide, we compute the guided mode and LPA solutions, then use these to compute the overlap integrals and phase terms in Eq. (36). While Eq.…”

Section: Validationmentioning

confidence: 99%

“…However, LPA and LUA cannot be applied to the "nonlocal" problem of radiation coupling to and from guided modes since in a periodic surface guided modes do * sefisher@mit.edu not radiate by definition [35]. This is in contrast to previous nonlocal metasurfaces employing leaky resonances [36][37][38][39][40][41][42][43] which radiate even for purely periodic surfaces [44]. On the other hand, guided-wave propagation can be treated by spatial coupled-wave theories (CWTs)-eigenmode-expansion methods resulting in a set of coupled ordinary differential equations in the mode coefficients, which can be solved perturbatively for slowly varying media [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…Other methods of domain decomposition besides LUA and LPA have been proposed to handle strong near-field intercell coupling, such as overlapping domains that model the overlapping regions from neighboring unit cells [61], combined with absorbing-wall domains that model each unit cell with perfectly matched layer boundary conditions [62]; however, these methods explicitly discard long-range interactions and hence omit guided-mode propagation. We also note that many techniques have been developed to design large-scale metasurface antennas, filters, and other devices at optical and microwave frequencies, but these make use of leaky waves rather than completely guided waves and thus solve a fundamentally different problem [36][37][38][39][40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Efficient perturbative framework for coupling of radiative and guided modes in nearly periodic surfaces

2022

View full text Add to dashboard Cite

We present a semianalytical framework for computing the coupling of radiative and guided waves in slowly varying (nearly uniform or nearly periodic) surfaces, which is especially relevant to the exploitation of nonlocal effects in large-area metasurfaces. Our framework bridges a gap in the theory of slowly varying surfaces: aside from brute-force numerical simulations, current approximate methods can model either guided or radiative waves but cannot easily model their coupling. We solve this problem by combining two methods: the locally periodic approximation, which approximates radiative scattering by composing a set of periodic scattering problems, and spatial coupled-wave theory, which allows the perturbative modeling of guided waves using an eigenmode expansion. We derive our framework for both nearly uniform and nearly periodic surfaces, and we validate each case against brute-force finite-difference time-domain simulations, which show increasing agreement as the surface varies more slowly.

show abstract

Chiral TeraHertz Surface Plasmonics

Aupiais,

Grasset,

Daineka

et al. 2024

ACS Photonics

View full text Add to dashboard Cite

Quasi-normal mode theory of the scattering matrix, enforcing fundamental constraints for truncated expansions

Cited by 22 publications

References 29 publications

Inverse Design of Metasurfaces Based on Coupled-Mode Theory and Adjoint Optimization

Inverse Design of Metasurfaces Based on Coupled-Mode Theory and Adjoint Optimization

Efficient perturbative framework for coupling of radiative and guided modes in nearly periodic surfaces

Chiral TeraHertz Surface Plasmonics

Contact Info

Product

Resources

About