All-Dielectric Near-Infrared Metasurface with Field Enhancement and High Q-Factor Based on Anapole Precise Manipulation

Anapole resonances with high-quality factor (Q-factor) can provide strong local electromagnetic fields for dielectric metasurfaces, combined with unique non-radiation which can play an important role in sensing, nonlinear optics, and other fields. Perfect anapole mode excitation is still a challenge in the near-infrared band. In this work, a method is proposed to realize the precise control of electric dipole (ED) and toroidal dipole (TD) by introducing elliptical air holes (EAH) and semi-elliptical slit (SES), so as to excite the perfect anapole mode. The proposed patterned-matesurface (Pa-Meta) is prepared by electron beam lithography (EBL) technology, and combined with the built spectral detection system, it is verified that the method can increase the Q-factor by 7.84 times (58 to 455). In addition, through the simulation calculation, the electric field enhancement factor |E/E0| can be increased by 5.87 times (9.2 to 54). Based on the anapole characteristic of patterned metasurfaces, An analysis of their sensing properties is conducted, revealing a sensitivity of 399.4 nm RIU-1. This study offers a novel perspective for accurately controlling anapole modes in all-dielectric metasurfaces, as well as their potential applications in optical sensing and spectroscopy.