Dual Quasi-Bound States in the Continuum Modes for Optical Activity Manipulation

Abstract

Quasi-bound states in the continuum (quasi-BIC) are a particular resonant state, which can be regulated by the degree of symmetry breaking in nanostructures. Here, we propose a fourfold rotationally symmetric (C 4v ) metasurface supporting the dual quasi-BIC modes. The Fano characteristics have observed in the near-infrared region. The resonant peaks of the dual quasi-BIC modes can be adjusted flexibly and independently with a simple breaking of the structural symmetry. More importantly, the dual quasi-BIC modes demonstrate the extraordinary capability in controlling the optical activity. This work will offer us more freedom for controlling the resonance and optical activity by the quasi-BIC modes, which is promising to engineer the optical device in displaying and optics communications.

Multiple Photonic Bound States in the Continuum in an Electromagnetically Induced Transparency Metasurface

“…She is now with the School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, P. R. China (e-mail: xsx@usst.edu.cn). associated high-Q resonances around a BIC point have earned considerable attention to construct ultra-sharp transmission/reflection spectra, leading to a giant near-field enhancement and various promising applications, such as BICbased chirality [8][9][10][11], lasing [12][13][14] beam shifting [15,16], decreasing radiative losses [17], nonlinearity [18][19][20][21][22], modulation [23,24] and sensing [25]. In photonic systems, one case is symmetry-protected BICs located at the center of Brillouin zone (Γ point), which is relevant to the complete incompatibility between resonant mode and radiative channels due to symmetry mismatch [5,26].…”