VO₂-enabled transmission-reflection switchable coding terahertz metamaterials

Abstract

Coding metamaterials have offered unprecedented degrees of freedom to manipulate electromagnetic waves in time and frequency domains in terms of various coding sequences, however, it is still challenging to realize dynamic coding metamaterials in the terahertz range. Here, we propose VO2-enabled transmission-reflection switchable coding terahertz metamaterials consisting of multilayered gold and VO2 patterns. The insulator-to-metal transition of VO2 leads to switch between the refractive and reflective scattering beams by changing the temperature. The four 2-bit elements are used to construct coding metasurface-based OAM generator with l = 1. Remarkably, the transmission-reflection switching functionality of the coding metasurface can be achieved at different frequencies. In addition, the novel designs in our work can achieve EM waves manipulation and provide a useful method to dynamically switch transmission-reflection response in the THz frequency regime.

Reprogrammable reflection-transmission integrated coding metasurface for real-time terahertz wavefront manipulations in full-space

“… Refs. Frequency Real-time tunable reflection and transmission Real-time tunable phase Active element Same frequency Same polarization 40 GHz No No – No No 41 GHz Yes No PIN diode Yes Yes 42 , 43 GHz Yes Yes PIN diode Yes Yes 52 , 53 , 56 THz No No - No No 44 , 51 , 54 , 60 THz Yes No Vo2 Yes Yes This work THz Yes Yes Graphene Yes Yes …”

“…This design allows real-time manipulation of waves in full space. However, as the frequency increases from microwave to terahertz, the availability of PIN diodes becomes limited, making their use impractical 44 . Consequently, achieving reprogrammable THz metamaterials that match the performance of existing microwave materials poses a significant challenge.…”

Temperature-switchable anti-reflective structure based on vanadium dioxide phase transition in the visible and near-infrared wavelength regions

“…In another research [29], switching the direction of reflection in a three ML structure consisting of Ge 2 Sb 2 Te 5 as a PCM has been investigated. One of the attractive PCMs is vanadium dioxide (VO 2 ), which can be used to control reflected light passing through a medium [29][30][31][32]. In the current work, VO 2 is considered in a temperature-switchable AR structure due to its extraordinary feature of reversible solid-solid semiconductor to metal phase transition around a critical temperature of 68 °C [33].…”

Frequency tunable switching between transmission and absorption modes based on graphene and VO2 layers at the THz range

“…So, device innovations that can dynamically switch and tune between transmission and absorption at the THz range are still a challenge. Flexible materials such as graphene [7,[10][11][12][13][14], plasma [15], Ge 2 Sb 2 Te 5 [12], and VO 2 [4,12,[16][17][18][19][20] provide a plausible solution to achieve reconfigurable THz wave switching .…”