Bandwidth-tunable THz absorber based on diagonally distributed double-sized VO₂ disks

Abstract

Terahertz absorbers combined with phase-changing V O 2 are a class of stealth materials with adjustable absorptance. However, such absorbers still suffer from insufficient absorption bandwidth. We propose a three-layer terahertz (THz) absorber, consisting of an array of diagonally distributed double-sized V O 2 disks on a silica-coated gold film. We find this structure can generate the superposition of three resonant absorption peaks to broaden the absorption band. The finite element simulation (FES) results show that the absorption bandwidth can be adjusted from 2.63 to 5.04 THz by simply changing the sizes of the V O 2 disks. In addition, the peak absorptance can be continuously regulated from 9.8% to 96% by varying the conductivity of V O 2 . Finally, the absorber is polarization-insensitive and has wide-angle absorption. The wide absorption band and adjustable bandwidth of the absorbers have important applications potentially for intelligent stealth materials.

Circular Dichroism Enhancement and Biosensing Application of Composite Dielectric Chiral Nanostructures

“…Vanadium dioxide (VO 2 ) is a phase change material, a sudden insulator−metal transition (IMT) occurs at a temperature of about 68 °C, resulting in dramatic changes in electromagnetic properties. 50 By the IMT characteristics of VO 2 , the absorption intensity of the nanosystem coupled between the nanostructure and VO 2 can be thermally switched for linearly polarized light 51 and perfect absorption and asymmetric transmission can be thermally switched for circularly polarized light. 52 Hence, the introduction of MoS 2 and VO 2 into our dielectric nanostructures is expected to enhance and dynamically adjust the CD signal of the dielectric nanostructures.…”

Dynamic Quarter‐Wave Metasurface for Efficient Helicity Inversion of Polarization Beyond the Single‐Layer Conversion Limit

“…[35] The roomtemperature-bonding technique developed here is compatible with high temperature and chemical etching, and is applicable to switchable multifunctional terahertz devices. [47,49,50]…”

“…[6] These two factors prevent the simultaneous achievement of orthogonal-polarization modulation and high efficiency, especially in terahertz or higher frequency regions. Although multilayer vanadium-dioxide metasurfaces have been seen as promising for use in efficient multifunctional devices, such as reconfigurable absorbers, [36][37][38][39][40][41][42][43][44][45][46][47][48] reprogrammable wavefront-engineering metasurfaces, [49,50] and devices switchable between quarterand half-wave plates, [51] these proposals have not been realized experimentally, because of the stringent fabrication challenges. Although a few studies have reported experimental realization of multilayer vanadium-dioxide structures for infrared polarization modulation [52] and terahertz asymmetric transmission, [53] they did not focus on orthogonal-polarization modulation.…”

Dynamic quarter-wave metasurface for efficient helicity inversion of polarization beyond the single-layer conversion limit

“…Checkerboard structures might be helpful for achieving broadband operation [35]. The room-temperature-bonding technique developed here is compatible with high temperature and chemical etching, and is applicable to switchable multifunctional terahertz devices [47,49,50].…”

“…These two factors prevent the simultaneous achievement of orthogonal-polarization modulation and high efficiency in any frequency region. Although multilayer vanadium-dioxide metasurfaces have been seen as promising for use in efficient multifunctional devices, such as reconfigurable absorbers [36,37,38,39,40,41,42,43,44,45,46,47,48], reprogrammable wavefront-engineering metasurfaces [49,50], and devices switchable between quarter-and half-wave plates [51], these proposals have not been realized experimentally, because of the stringent fabrication challenges. (Although a few studies have reported experimental realization of multilayer vanadium-dioxide structures for infrared polarization modulation [52] and terahertz asymmetric transmission [53], they did not focus on orthogonalpolarization modulation.)…”