Graphene-based metasurface absorber for the active and broadband manipulation of terahertz radiation

Abstract

Graphene-based metasurface nearly perfect absorbers (MPAs) can be used as an efficient tool for the active control and manipulation of waves in the terahertz (THz) gap. Here, we propose a novel, to the best of our knowledge, graphene-based MPA that is designed based on a simple configuration and is capable of absorbing THz radiation within a broad bandwidth of almost 3 THz with polarization-insensitive and omnidirectional characteristics. The MPA comprises a periodic array of graphene patches with two different dimensions that are separated from a gold bottom reflector with an SiO 2 spacer layer. The broadband spectral response of the MPA, which is also verified by analytical calculations, is due to the support of propagating surface plasmon excitations and can be either actively tuned via changes in the chemical potential of graphene or passively adjusted by the modification of the geometrical parameters of the patches and thickness of the spacer layer. As a complement to the previous studies in the literature, due to the simplicity of its design and broad spectral response, it is believed that the suggested graphene-based MPA will find potential applications in THz spectroscopy and communications.

Metamaterial Absorbers: From Tunable Surface to Structural Transformation

“…[ 87 ] In a most recent work from Bosdurmaz et al., an MA with a periodic array of two graphene patches with different sizes has been designed and analytically verified to achieve a broadband absorption of 3 THz as well as a tunability of both the operating frequency and the absorbing bandwidth. [ 73 ] Note that the tunability of all aforementioned MAs is based on the change in E f of graphene by applying external bias voltages, which is effective and convenient to control the response of MAs.…”

“…As illustrated in Figure 6a,b, by controlling the V g , the E f of graphene can be tuned, resulting in the conveniently and dynamically tunable absorption performance of MAs. [74,104,163,167] Currently, both graphene films [107,163] and graphene patterns [73,162,164,[168][169][170] with single-layer or multilayer structures have been employed in tunable MAs designs. In a work from Ye et al, a frequencyreconfigurable narrowband MA has been proposed using double-layer graphene ribbon with decussate arrays (Figure 6c) to significantly enhance the relative frequency tunability as well as the angular stability.…”

“…[4,62,64] In addition, broadband absorption can also be achieved by incorporating these lumped elements, followed by selecting optimized values of these elements. [65][66][67] In addition to lumped elements, active materials including phase-change materials (PCMs), [27,30,41,[68][69][70][71] 2D materials, [18,[72][73][74][75][76] shape-memory materials (SMMs), [77][78][79][80] and liquid metals, [81][82][83] have also been explored in the design of tunable/reconfigurable MAs due to their change in electrical properties under external stimuli including heat, electric field, and light. The integration of active materials to MAs design has been found to be effective in controlling EM properties of MAs (Figure 2g) operating at frequencies from gigahertzes (GHz), terahertz (THz), infrared (IR) and even to optical regimes.…”

Adaptive thermally tunable radiative cooling with angle insensitivity using phase-change-material-based metasurface

“…These artificially engineered materials are distinguished by their exceptional optical, and thermal properties, making them promising candidates for the development of novel devices that can manipulate thermal radiation in innovative ways. These artificial materials typically include geometrical shapes such as gratings [13], crosses [14], and hole-arrays [15] or they can be planar [16] surfaces to achieve strong light-matter interactions in terahertz [17], nearinfrared [18], and mid-infrared [19] regimes.…”

Tunable Ultra-Broadband Terahertz Metamaterial Absorbers Based on Complementary Split Ring-Shaped Graphene

“…Among those, the most notable property is that the conductivity and permittivity of graphene can be dynamically tuned by varying the Fermi energy through external bias voltage and chemical doping. Utilizing such a special property, a great number of tunable THz metamaterial absorbers based on various graphene structures like disks [28], [29], ribbons [30]- [32], patches [33], [34], cross shnets [35], hourglass [36], fractal [37] and other microstructures [38]- [42] have been proposed. Nevertheless, the above mentioned tunable absorbers still suffer from the di culty of absorption tuning via bias voltage, because their discrete graphene patterns inevitably cause great barriers in practical fabrication and electrical control of graphene-based metamaterial absorbers.…”