Abstract
We numerically demonstrate an ultra-wideband terahertz absorber using dielectric circular truncated cones on a non-structured graphene layer supported by a dielectric spacer on a metal reflector in the bottom. The absorber has an ultra-wideband absorption bandwidth from 0.34 to more than 10 THz with an average absorbance of 95.88% and a relative bandwidth of 186% because of the continuous multimode Fabry-Perot (FP) resonances. The absorber also possesses excellent absorption characteristics with polarization independence under normal incidence and angular stability up to 60°. The proposed ultra-wideband absorber may have promising applications in terahertz trapping, imaging, and detecting.
Highlights
Terahertz technology has attracted extensive attention in recent years [1]
We numerically demonstrate an ultra-wideband terahertz absorber using dielectric circular truncated cones on a non-structured graphene layer supported by a dielectric spacer on a metal reflector in the bottom
We propose a novel ultra-wideband terahertz absorber based on dielectric circular truncated cones on a non-structured graphene layer supported by a dielectric spacer on a metal reflector in the bottom
Summary
Terahertz technology has attracted extensive attention in recent years [1]. As one of the key devices in terahertz region, terahertz absorbers have great applications in terahertz imaging, thermal detectors, and communication [2]–[5]. Various terahertz absorbers with different structures including electric ring resonators (ERRs) [6], [7], patterned graphene absorbers [8]–[13], and all dielectric absorbers [14], [15] have been investigated. Most of these absorbers are operating in a single-band, dual-band, or multi-band with limited absorption bandwidth. Xu et al proposed an ultra-broadband absorber based on multilayer-graphene with an absorption band ranging from 3 to 7.8 THz and a relative bandwidth of 89% [16]. The ultra-wideband absorption characteristic of the proposed absorber is mainly attributed to the continuous multimode FP resonances, which is fundamentally different from the localized surface plasmon resonance of the patterned graphene in the reported broadband graphene absorbers [8]–[13]
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