High Q-factor fano resonances on permittivity-asymmetric dielectric meta-surfaces

We designed ab all-dielectric device based on permittivity-asymmetric rectangular holes, yielding multiple Fano resonances with high Q-factor in the near-infrared regime. there is a newly-generated sharp Fano peak with arising from the interference between sub-radiant modes and the electric and magnetic dipole resonance modes. Combining the multipole decomposition based on cartesian system and the field distribution, the resonance modes are analyzed to be toroidal dipole (TD) and magnetic dipole (MD). Furthermore, the dependence on materials and geometric parameters has been studied and the maximal quality (Q)-factor reaches 28503. This structure may be used for optical switching, nonlinear optical devices, and laser