Wide-Band Circularly Polarized ReflectarrayUsing Graphene-Based Pancharatnam-Berry Phase Unit-Cells for Terahertz Communication

Abstract

A wide-band and high gain circularly polarized (CP) graphene-based reflectarray operating in the THz regime is proposed and theoretically investigated in this paper. The proposed reflectarray consists of a THz CP source and several graphene-based unit-cells. Taking advantages of the Pancharatnam Berry (PB) phase principle, the graphene-based unit-cell is capable of realizing a tunable phase range of 360° in a wide-band (1.4–1.7 THz) by unit-cell rotating, overcoming the restriction of intrinsic narrow-band resonance in graphene. Therefore, this graphene-based unit-cell exhibits superior bandwidth and phase tunability to its previous counterparts. To demonstrate this, a wide-band (1.4–1.7 THz) focusing metasurface based on the proposed unit-cell that exhibits excellent focusing effect was designed. Then, according to the reversibility of the optical path, a CP reflectarray was realized by placing a wide-band CP THz source at the focal point of the metasurface. Numerical simulation demonstrates that this reflectarray can achieve a stable high gain up to 15 dBic and an axial ratio around 2.1 dB over the 1.4–1.7 THz band. The good radiation performance of the proposed CP reflectarray, as demonstrated, underlines its suitability for the THz communication applications. Moreover, the design principle of this graphene-based reflectarray with a full 360° phase range tunable unit-cells provides a new pathway to design high-performance CP reflectarray in the THz regime.

A Review on the Development of Tunable Graphene Nanoantennas for Terahertz Optoelectronic and Plasmonic Applications

“…Li Deng and coworkers theoretically inspected a circularly polarized graphene-based reflectarray to achieve wide bandwidth and better gain in the terahertz region [242]. The investigated graphene-based reflectarray was excited by a terahertz circularly polarized source (Figure 18g).…”

Mode‐switchable orbit angular momentum waves by mechanically rotating 2 bit phase quantization transmitarray

“…However, the feed network tends to be much more complex as the total number of controlled OAM modes increases, while the complicated feed network produces high costs and serious divergence between different OAM modes, which makes them limited in practical applications. (2) Reconfigurable MSs by varactor diodes, PIN diodes or employing tunable metaparticles (such as vanadium dioxide, 19 graphene, 20 liquid crystal, 21 etc.). With low profile, low cost and simple feed structure, the 1‐bit or 2‐bit reflective programable MSs are proposed by using reconfigurable units integrated with the voltage‐controlled varactor diodes or PIN diodes 22 .…”

Terahertz Reconfigurable Metasurface for Dynamic Non-Diffractive Orbital Angular Momentum Beams using Vanadium Dioxide

“…In the optical regime, such control can be achieved straightforwardly using devices such as spatial light modulators [23], but such technology is not readily available in the microwave or THz bands. As such, in recent years, significant effort has been made to develop reconfigurable metasurfaces by employing tunable metaparticles, such as vanadium dioxide (VO 2 ) [24], indium tin oxide [25], graphene [26], liquid crystal [27] germanium antimony telluride (GST) [28], InSb/In0.8Al0.2Sb heterojunctions [29], micro-electromechanical systems (MEMS) [30], varactor diodes [31], and PIN diodes [32].…”