Vanadium dioxide-assisted switchable multifunctional metamaterial structure

Abstract

A multifunctional design based on vanadium dioxide (VO2) metamaterial structure is proposed. Broadband absorption, linear-to-linear (LTL) polarization conversion, linear-to-circular (LTC) polarization conversion, and total reflection can be achieved based on the insulator-to-metal transition (IMT) of VO2. When the VO2 is in the metallic state, the multifunctional structure can be used as a broadband absorber. The results show that the absorption rate exceeds 90% in the frequency band of 2.17 - 4.94 THz, and the bandwidth ratio is 77.8%. When VO2 is in the insulator state, for the incident terahertz waves with a polarization angle of 45°, the structure works as a polarization converter. In this case, LTC polarization conversion can be obtained in the frequency band of 0.1 - 3.5 THz, and LTL polarization conversion also can be obtained in the frequency band of 3.5 - 6 THz, especially in the 3.755 - 4.856 THz band that the polarization conversion rate is over 90%. For the incident terahertz waves with a polarization angle of 0°, the metamaterial structure can be used as a total reflector. Additionally, impacts of geometrical parameters, incidence angle and polarization angle on the operating characteristics have also been investigated. The designed switchable multifunctional metasurfaces are promising for a wide range of applications in advanced terahertz research and smart applications.

A tri-functional, independently tunable terahertz absorber based on a vanadium dioxide–graphene hybrid structure

“…The Drude model can be employed to depict the dielectric constant of VO 2 around the terahertz frequency: 30,31…”

“…The Drude model can be employed to depict the dielectric constant of VO 2 around the terahertz frequency: 30,31 where ε ∞ is defined as the high-frequency relative permittivity of VO 2 , with a specific value of 12; γ , which represents the collision frequency, is assigned a numerical value of 5.75 × 10 13 rad s −1 ; ω is the frequency of the incident electromagnetic wave. ω p 2 ( σ ) is the plasma frequency associated with the conductivity of VO 2 and satisfies eqn (6):where σ 0 = 3 × 10 5 S m −1 , ω p 2 ( σ 0 ) = 1.4 × 10 15 rad s −1 .…”

Actively tunable and switchable terahertz metamaterials with multi-band perfect absorption and polarization conversion

“…4,5 Metamaterials, 6 as a new type of artificial composite material with a sub-wavelength periodic unit cell, have attracted much attention due to their wide-ranging applications, 7 such as electromagnetic cloaking, 8 metalens, 9 perfect absorption, 10 and polarization conversion. 11 The flexible design of the meta-atoms allows for the effective permittivity and permeability of metamaterials to be artificially set. Since Landy first proposed the metamaterial perfect absorber, 12 different types of metamaterial absorbers have been presented theoretically and experimentally, with operating bands ranging from narrowband 13,14 to dual-band, 15 multi-band, 16 and broadband ranges, 17,18 and with operating frequencies ranging from microwave 19 to terahertz, 20 infrared waves, 21 and even visible light frequencies.…”

Metallic VO2−x Nanobeam Implanted With an Insulating VO2 Segment Toward Artificial Electrical Modulation

“…A field-dependent IMT can be triggered in VO 2 by external thermal, [1] stress, [2] electrical, [3] or optical stimuli. [4,5] VO 2 has been one of the candidates for Mott field-effect transistors, [6,7] photodetectors, [8][9][10] electrical switches, [11] smart windows, [12][13][14][15][16] and thermal regulators. [17,18] To manipulate IMT on the nanoscale is of broad scientific interest and is always critical for functional vanadium oxides toward advanced sensors and information devices.…”

“…A field‐dependent IMT can be triggered in VO 2 by external thermal, [ 1 ] stress, [ 2 ] electrical, [ 3 ] or optical stimuli. [ 4,5 ] VO 2 has been one of the candidates for Mott field‐effect transistors, [ 6,7 ] photodetectors, [ 8–10 ] electrical switches, [ 11 ] smart windows, [ 12–16 ] and thermal regulators. [ 17,18 ]…”