Large-range, continuously tunable perfect absorbers based on Dirac semimetals

Abstract

Plasmonic metamaterials enable manipulation of light at subwavelength scales and exhibit unique optical functionalities. However, the realization of high-performance, large-range, and dynamically tunable optical absorbers based on plasmonic metamaterials remains challenging. Here, we propose and demonstrate a continuously tunable absorbers consisting of a zigzag array of bulk Dirac semimetals (BDS) meta-atoms and a metal reflector spaced by insulator layers. This structure exhibits a collective resonance formed by the electric dipole modes polarized along the long axis of each individual meta-atom, which allows us to precisely control this resonance frequency by fine-tuning the unit cell geometry and the Fermi energy levels of the BDS. In addition, the related physical mechanism behind this complete absorption can explained by employing coupled-mode theory (CMT) and mode-expansion theory (MET). Our results may arouse the investigations of the tunable metamaterials device based on the BDS.

Dynamically tunable multi-band coherent perfect absorption based on InSb metasurfaces

“…The length, width, and thickness of the InSb strip are l 1 = 140 µm (l 2 = 55 µm), d 1 = 7.8 µm (d 2 = 22 µm), and h = 1 µm, respectively. The refractive index of SiO 2 is n = 2.1025 and can be regarded as lossless [28,29]. The relative permittivity of InSb is estimated by the Drude model as follow [30,31]:…”

Study on vanadium dioxide based terahertz metamaterials with switchable functions from five-band absorption to triple-band plasmon-induced transparency

“…Meanwhile, the electromagnetic behavior of metamaterials can only be adjusted by changing the sizes of patterns, so that changing operating frequency or working intensity seems like an impossible thing to do, which not only wastes materials to a great extent, but also lacks real-time modulation performance and compatibility. To enable switching of different functions in the same device, tunable materials are often introduced into the design of metamaterials, such as liquid crystal [53], graphene [54,55], and Dirac semimetals [56][57][58][59]. For instance, a dual-tuned broadband metamaterial absorber based on Dirac semimetals and water that can operate in the terahertz band was proposed [60].…”