Dynamically electrical/thermal-tunable perfect absorber for a high-performance terahertz modulation

Abstract

We present a high-performance functional perfect absorber in a wide range of terahertz (THz) wave based on a hybrid structure of graphene and vanadium dioxide (VO2) resonators. Dynamically electrical and thermal tunable absorption is achieved due to the management on the resonant properties via the external surroundings. Multifunctional manipulations can be further realized within such absorber platform. For instance, a wide-frequency terahertz perfect absorber with the operation frequency range covering from 1.594 THz to 3.272 THz can be realized when the conductivity of VO2 is set to 100000 S/m (metal phase) and the Fermi level of graphene is 0.01 eV. The absorption can be dynamically changed from 0 to 99.98% and in verse by adjusting the conductivity of VO2. The impedance matching theory is introduced to analyze and elucidate the wideband absorption rate. In addition, the absorber can be changed from wideband absorption to dual-band absorption by adjusting the Fermi level of graphene from 0.01 eV to 0.7 eV when the conductivity of VO2 is fixed at 100000 S/m. Besides, the analysis of the chiral characteristics of the helical structure shows that the extinction cross-section has a circular dichroic response under the excitation of two different circularly polarized lights (CPL). Our study proposes approaches to manipulate the wide-band terahertz wave with multiple ways, paving the way for the development of technologies in the fields of switches, modulators, and imaging devices.

Tunable VO2 cavity enables multispectral manipulation from visible to microwave frequencies

“…In the THz and MW regions, the dielectric constants of VO 2 can be described using the Drude model 45 , 46 : where ε ∞ = 12 is dielectric permittivity at the infinite frequency, is the plasma frequency of VO 2 that dependent on conductivity, = 5.75 ×10 13 rad· s −1 is the collision frequency, = 3 ×10 5 S· m −1 , = 1.5 ×10 15 rad· s −1 , is the conductivity of VO 2 (Fig. 4d and Supplementary Fig.…”

Switchable Broadband Terahertz Absorbers Based on Conducting Polymer‐Cellulose Aerogels

“…[18,19] Similarly, studies on aerogels composed of phase change materials exhibited switching behavior, but with a more limited tuning range. [13,14] For example, Chang et al reported RL tuned from −17 to −54 dB, corresponding to a modulation in absorption in the range from 98% to ≈100%. [28] In addition, the tuning often covered a relatively narrow band with frequencies mostly located in the microwave range instead of in the THz range.…”

“…Switchable materials that can modulate the absorption or transmission of THz signals are useful for intelligent calibration targets, dynamic attenuators for THz optical circuits, and effective modulators for electromagnetic interference, as demonstrated by multiple simulation results. [13][14][15] Only a few materials have shown decent tunability in the THz range, [13,14,[16][17][18][19] despite significant research progress in electromagnetic absorbers. [20][21][22][23][24][25][26] Several of these systems focused on modulating THz properties via reflection rather than absorption, and often with limited tuning range.…”

Frequency Reconfigurable and Multifunctional Metastructure Regulated by Nematic Liquid Crystal: Broadband Circular to Linear Polarization Converter

“…[32] Hence, in-depth studies on the versatile or frequency reconfigurable MS enter a new boom by combining metallic resonators and tunable materials. Considerable methods of regulation include but are not limited to temperature, [33,34] gravity field, [35] illumination, [36,37] and electric field. [38] For instance, Singh et al experimentally demonstrated and compared the thermal tuning of the fundamental inductive-capacitive resonance, where metals and superconductors are discussed, to active MS resonance tuning.…”

“…[ 32 ] Hence, in‐depth studies on the versatile or frequency reconfigurable MS enter a new boom by combining metallic resonators and tunable materials. Considerable methods of regulation include but are not limited to temperature, [ 33,34 ] gravity field, [ 35 ] illumination, [ 36,37 ] and electric field. [ 38 ] For instance, Singh et al.…”