Multifunctional Reconfigurable Electromagnetic Metamaterials Based on Compression‐Torsion Coupling Structures for Transmission Modulations and Holographic Displays

Abstract Mechanically controlled reconfigurable electromagnetic metamaterials that can dynamically modulate their electromagnetic properties by simple mechanical compression/stretch hold great potential in wavefront control, tunable filtering, and holographic display. Undesired operating frequency shift and difficult independent controlling of unit cells in existing mechanically controlled reconfigurable metamaterials greatly limit their wide developments. Here, a multifunctional reconfigurable electromagnetic metamaterial based on a compression‐torsion coupling structure with the unit cell featuring a split‐ring resonator, a pair of parallel square frames, and four inclined beams between the frames, is reported. The unit cells can be globally or selectively compressed to induce the uniform or patterned in‐plane rotations of split‐ring resonators, enabling the multifunctionalities of electromagnetic transmission modulation and holographic display, which are not easily accessible by existing mechanically controlled electromagnetic metamaterials based on in‐plane compression and tension schemes. Numerical and experimental studies are carried out to reveal the design and operation of reconfigurable metamaterials enabled by the compression‐torsion coupling structure. Demonstrations of the metamaterials in modulating the transmittance of linearly polarized waves with stable resonant frequencies and multi‐imaged holographic display functions illustrate the versatility and feasibility of compression‐torsion strategy in realizing multifunctional electromagnetic metamaterials.