Multiple Fano resonances on the metastructure of all-dielectric nanopore arrays excited by breaking two-different-dimensional symmetries.

We have designed and analyzed the high quality-factor (Q-factor), multiple Fano resonances device on the basis of the all-dielectric metastructure. The unit structure consists of two rectangular air holes etched within a silicon cube and periodically aligns on the substrate of silicon dioxide. The results demonstrate that four Fano resonances are achieved by integrating the theory of bound states in the continuum (BIC)and breaking the symmetry (width symmetry or depth symmetry) of two rectangle air holes, and the resonant wavelength can be modified by altering structural parameters. The sensing characteristics of the presented structure are studied. The sensitivity(S) of 304 nm/RIU, the maximal Q-factor of 2142 and the figure of merit (FOM) of 515.3 are achieved while width symmetry is broken. Meanwhile, the sensitivity of 280 nm/RIU, the maximal Q-factor of 2517 and the FOM of 560 are gotted through breaking depth symmetry. The proposed metastructures can be used for the lasers, biosensing and nonlinear optics.