Broadband Polarization‐Insensitive Coherent Rasorber in Terahertz Metamaterial with Enhanced Anapole Response and Coupled Toroidal Dipole Modes

Abstract

AbstractEnhanced anapole and coupled toroidal dipole moments sustaining the synthesized terahertz (THz) metamaterial innovatively promise for absorption‐transmission‐absorption (ATA) metamaterial rasorber (MMR). The anapole mode, due to the strong interaction of electric and magnetic dipole moments, and Fabry–Pérot resonance are supported by the dumbbell‐shaped apertures topologically distributed in a double‐layer silver plate, thus forming the transmission window with high frequency‐selectivity. Meanwhile, the coupled toroidal dipole moments depending on the toroidal structure can cause destructive and constructive interference in far and near fields, respectively, thus causing much electromagnetic energy loss in a wide band. Combining anapole with toroidal dipole moments, the ATA MMR depending on the THz metamaterial can attain high absorption (over 0.88) at 1.46–2.29 THz with relative absorption bandwidth (RABW) of 44.27%, and at 3.51–4.3 THz the RABW of 20.26%, and simultaneously the transmission (over 0.7) window covering 2.9–3.21 THz, with relative transmission bandwidth (RTBW) of 10.3%. These superior properties of the MMR promise a great potential for practical application in radar and electromagnetic stealth fields. Furthermore, the innovative combination of anapole and toroidal dipole moments in the MMR assists in enriching the theoretical framework and strategically opening up state‐of‐the‐art pathways of multipole electrodynamics.