Merging absorption bands of plasmonic structures via dispersion engineering

Abstract

In this paper, a comprehensive scheme based on the dispersion engineering of spoof surface plasmon polariton (SSPP) is proposed which attempts to merge absorption bands of plasmonic structure into a continuous one. Theoretical investigation shows that multi-resonance can be tailored in a meandered wire structure, and thus, the closed interval of adjacent absorption is achieved. Then, the plasmonic absorbing structure (PAS) consisting of a meandered wire array with the gradient length are employed here to achieve spatial k-dispersion engineering of SSPP, and the original isolated absorption bands are demonstrated to be merged into a continuous one. On such a basis, a hybrid PAS consisting of a meandered wire array and a straight wire array is proposed. Simulation and experimental measurements show that the proposed hybrid PAS can achieve ultra-wideband absorption with an efficiency of more than 90% in the frequency range of 5.0–31.6 GHz, which is 107.7% broader with respect to the original PAS of the straight wire array at the same thickness. Our strategy overcomes the contradiction between broadening absorption bandwidth and keeping high absorption efficiency in PAS, enabling a wide range of applications, such as radar stealth technology, electromagnetic compatibility, and so on.