Dynamic Beam Switching by the Highly Sensitive Metasurface Composed of All-Metallic Split-Ring Resonators

The development of metasurfaces capable of arbitrarily manipulating electromagnetic waves has created new opportunities for various applications. However, most tunable metasurface devices via different modulation techniques exhibit large fabrication difficulties or narrow bandwidths. Here, we use the all-metallic split-ring resonator to design a dynamically tunable metasurface that is highly sensitive to the ambient refractive index and capable of broadband beam switching. Different from the previous optical scatters, the split-ring resonator is put on the metal substrate. Due to the existence of metallic substrate and large interaction of corner modes, the proposed resonator has small ohmic loss and high sensitivity to the ambient refractive index. By arraying the all-metallic split-ring resonators with different parameters, dynamic beam switching of anomalous reflection is demonstrated numerically. In particularly, the designed metasurface exhibits the dynamic beam switching in a broadband wavelength range of Δλ≈100 nm. Such an all-metallic metasurface with high sensitivity can greatly reduce the designing difficulty of the tunable optical devices. The dynamic metadevices may find potential applications in stealth camouflage, information encryption, and data storage.