Resonant field enhancement near bound states in the continuum on periodic structures

Abstract

On periodic structures sandwiched between two homogeneous media, a bound state in the continuum (BIC) is a guided Bloch mode with a frequency within the radiation continuum. BICs are useful, since they give rise to high quality-factor ($Q$-factor) resonances that enhance local fields for diffraction problems with given incident waves. For any BIC on a periodic structure, there is always a surrounding family of resonant modes with $Q$-factors approaching infinity. We analyze field enhancement around BICs using analytic and numerical methods. Based on a perturbation method, we show that field enhancement is proportional to the square-root of the $Q$-factor, and it depends on the adjoint resonant mode and its coupling efficiency with incident waves. Numerical results are presented to show different asymptotic relations between the field enhancement and the Bloch wavevector for different BICs. Our study provides a useful guideline for applications relying on resonant enhancement of local fields.

References in corpus (4)

• Topological nature of bound states in the radiation continuum
• Bloch bound states in the radiation continuum in a periodic array of dielectric rods
• Bound states with complex frequencies near the continuum on lossy periodic structures
• Indirect link between resonant and guided modes on uniform and periodic slabs

Cited by in corpus (9)

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• Parametric Dependence of Bound States in the Continuum on Periodic Structures
• Parametric dependence of bound states in the continuum in periodic structures: vectorial cases
• Parametric dependence of bound states in the continuum: a general theory
• On the robustness of bound states in the continuum in waveguides with lateral leakage channels
• Resonant field enhancement in lossy periodic structures supporting complex bound states in the continuum
• A Fourier-matching Method for Analyzing Resonance Frequencies by a Sound-hard Slab with Arbitrarily Shaped Subwavelength Holes
• Frequency perturbation theory of bound states in the continuum in a periodic waveguide