Beyond dipole excitation: the performance of quadrupole-based Huygens' metasurface.

Due to the utilization of overlapped dipole resonances, traditional Huygens' metasurfaces suffer from dipole interactions. In this Letter, we propose a design of phase-gradient Huygens' metasurface based on the quadrupole resonances excited in the cross-shaped structures. The quadrupole resonances are theoretically shown insensitive to the quadrupole interactions. Benefiting from this intrinsic property, the proposed metasurface can well suppress element interaction influence and exhibits some impressive properties, including the ability to suppress high diffraction orders, tunable anomalous refractive angles, and high transmission efficiency. The numerical results show promising potential for quadrupole resonances to be applied in advanced Huygens' metasurface designs.