Experimental Realization of a Superdispersion‐enabled Ultrabroadband Terahertz Cloak

Invisibility has been a topic of long-standing interest owning to the advent of metamaterials and transformation optics, but still faces open challenges after its tremendous development in recent decades. One of the big challenges is the narrow bandwidth, as the realization of an invisibility cloak is usually based on a metamaterial - an artificial composite material composed of subwavelength resonator structures that are always associated with dispersion. Different from previous works that tried to eliminate the material dispersion to enhance the bandwidth of the invisibility cloak, in this paper, we find that by judiciously harnessing the material dispersion, one can still significantly increase the bandwidth of the cloak. Interestingly, the material dispersion does not violate the law of causality. As a proof of concept, we experimentally demonstrate an ultrabroadband terahertz (THz) carpet cloak through an array of superdispersive microparticles, rendering the target object invisible to the detection of both time- and frequency-domain wideband systems. Our work presents a feasible invisibility strategy that is closer to practical applications and may pave a brand-new way for the development of dispersion-dominated ultrabroadband metadevices. This article is protected by copyright. All rights reserved.