Open AccessBandwidth bounds of coherent perfect absorber in resonant metasurfaces
Author(s) -
Ming Kang,
Ming Li,
Jing Chen
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.009004
Subject(s) - physics , bandwidth (computing) , resonator , radiative transfer , optics , coupled mode theory , resonance (particle physics) , q factor , microwave , dissipation , scattering , computational physics , atomic physics , quantum mechanics , refractive index , telecommunications , computer science
Coherent perfect absorber (CPA), a resonator with critical losses that can perfectly absorb all incident light, has been observed at various frequency regimes (from microwave to visible light). Besides the functional frequency, the bandwidth is also an important parameter in characterizing the performance of CPA. Here, we explore the bandwidth of CPA in a kind of weakly-coupled-resonance metasurfaces with 4κ 2 -γs2<0, where κ is the near-field coupling between the radiative and non-radiative resonant modes, and γ s is the scattering loss rate of the radiative resonant mode. Based on the coupled mode theory, we analytically derive the upper and lower bounds of the bandwidth, and show that they are determined by the dissipation loss rates of the composed modes. To narrow the bandwidth, it is better to increase the radiative loss rate when designing a weakly coupled resonator. We also show that CPA is associated with a robust phase singularity with a winding number of ± 1. The conclusions are numerically verified in a designed resonant metasurface and could perform as a guideline for designing CPA in various resonant systems.