Graphene-Integrated Nonradiative Anapole-Mode Metasurfaces for Sensing

The nonradiative anapole mode is a unique state of light induced by the interference of electric and toroidal dipole (TD) moments, which can be used to enhance the nonlinear electromagnetic properties of materials in micro-nanophotonics. In this work, we propose and experimentally demonstrate a graphene-integrated anapole mode metasurface (Gr-AnMS) used for the ultrasensitive quantitative detection of the insecticide acetamiprid in the terahertz region. The limit of detection (LOD) of this Gr-AnMS sensor for acetamiprid is 10.72 fg/ml and the depth of modulation is 43.78%. The unique electromagnetic properties of the anapole mode and the fact that a slight change in the dielectric environment causes the Fermi level (
${E}_{F}$
) of graphene to move to the Dirac point combine to enable the ultrasensitive detection of acetamiprid. The anapole metasurface provides a platform for effective control of far-field radiation and near-field enhancement in optics, which is a promising basis for quantitative detection in chemical and biological sensing.