Abstract
The active control to the local resonant mode of metasurface is a promising route for improving the operation bandwidth limitation of metasurface. Here, we propose and experimentally demonstrated the active tunabilities in a frequency-agile Fano-resonant metasurface. The metasurface with a pair of asymmetric split ring resonators is integrated with double varactor diodes for active control of the sharp Fano resonance. It is found that the sharp Fano-type spectrum appears due to the near-field interferences between the collective electric and magnetic dipole modes. The physical insight is revealed through local field analysis, multipole decomposition and temporal coupled-mode theory. It is also found that the metasurface can be employed as a broadband and unity modulator. Hopefully, our results could inspire sophisticated electrically controlled photonic devices with novel functions.
Highlights
Metamaterials are artificial engineered subwavelength structures with tailorable properties superior to the natural materials, which have shown unprecedented capability in exterior light manipulations [1,2,3,4,5]
It consists of a pair of asymmetric split ring resonators (ASRRs) with different side lengths
Four inductors are located between the bias wires and ASRRs to effectively avoid the cross talk
Summary
Metamaterials are artificial engineered subwavelength structures with tailorable properties superior to the natural materials, which have shown unprecedented capability in exterior light manipulations [1,2,3,4,5]. Since three-dimensional metamaterials are difficult to design and fabricate, their twodimensional (2D) counterpart, metasurfaces [6,7,8,9,10], constructed by subwavelength metallic or dielectric particles in a planar platform, have attracted considerable attention in recent years for the arbitrary control of electromagnetic waves [11,12,13]. Metasurfaces have inspired extraordinary light manipulations such as invisibility cloak [14], broadband achromatic metalens [15], arbitrary orbital angular momentum generation [16], enhanced nonlinear photonics [17], and meta-hologram [18]. Metasurfaces with so-called bright and dark modes are designed to resemble the original physical mechanism of Fano resonance [26,27,28], i.e., interference between a narrow discrete resonance with a broadband spectral line in a quantum system.
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