Planar chiral metasurfaces with maximal and tunable chiroptical response driven by bound states in the continuum

Optical metasurfaces with high quality factors (Q-factors) of chiral resonances can boost substantially light-matter interaction for various applications of chiral response in ultrathin, active, and nonlinear metadevices. However, current approaches lack the flexibility to enhance and tune the chirality and Q-factor simultaneously. Here, we suggest a design of chiral metasurface supporting bound state in the continuum (BIC) and demonstrate experimentally chiroptical responses with ultra-high Q-factors and near-perfect circular dichroism (CD = 0.93) at optical frequencies. We employ the symmetry-reduced meta-atoms with high birefringence supporting winding elliptical eigenstate polarizations with opposite…

• NN
  National Natural Science Foundation of China

  Awards: 62075084, 12074420
• FR
  Fundamental Research Funds for the Central Universities

  Award: 21620415
• BA
  Basic and Applied Basic Research Foundation of Guangdong Province

  Awards: 2020A1515010615, 2022B1515020004