Recent Progress on Graphene-Functionalized Metasurfaces for Tunable Phase and Polarization Control

Abstract

The combination of graphene and a metasurface holds great promise for dynamic manipulation of the electromagnetic wave from low terahertz to mid-infrared. The optical response of graphene is significantly enhanced by the highly-localized fields in the meta-atoms, and the characteristics of meta-atoms can in turn be modulated in a large dynamic range through electrical doping of graphene. Graphene metasurfaces are initially focused on intensity modulation as modulators and tunable absorbers. In this paper, we review the recent progress of graphene metasurfaces for active control of the phase and the polarization. The related applications involve, but are not limited to lenses with tunable intensity or focal length, dynamic beam scanning, wave plates with tunable frequency, switchable polarizers, and real-time generation of an arbitrary polarization state, all by tuning the gate voltage of graphene. The review is concluded with a discussion of the existing challenges and the personal perspective of future directions.

Tunable Bound States in the Continuum in All-Dielectric Terahertz Metasurfaces

“…Generally, most of the aforementioned dielectric metasurfaces exhibit fixed functionalities once fabricated, which is unable to support a dynamic resonance and thus limit many practical applications. By integrating with active materials such as semiconductors, liquid crystals, graphene, and phase-change materials [21,[29][30][31][32][33], some metasurfaces were proposed with tunable characteristics whereas only the resonance amplitude or frequency can be tuned. For example, the optically induced dynamic control and modulation of sharp BIC resonances are demonstrated by Fan et al and Han et al in the silicon-based THz metasurfaces [21,29].…”

Efficient Optical Reflection Modulation by Coupling Interband Transition of Graphene to Magnetic Resonance in Metamaterials

“…Dynamically controlling the spectral properties of electromagnetic waves by external stimuli such as mechanical force, temperature change, electrical voltage, and laser beam [1][2][3][4] has been drawing increasing interest, because of many applications in the fields of holographic display technology, highperformance sensing, and optical communications. In the past few years, much effort has been made to actively manipulate the transmission, reflection, or absorption spectra of electromagnetic waves, which is based on electrically tunable surface conductivity of graphene, in a very wide frequency range including microwave [5,6], terahertz (THz) , infrared , and visible regime [66][67][68][69].…”

“…Such graphene-based active manipulation of electromagnetic waves is under external electrical stimulus without re-building-related structures, which aims to efficiently modulate the amplitude [5, 7-21, 34-57, 66-72], phase [6,[22][23][24][25][26][27][28][58][59][60][61][62], and polarization [29-33, [63][64][65] of electromagnetic waves. The three kinds of electromagnetic wave modulators are the most important for signal processing in free-space optical communications [1][2][3][4]. In the far-infrared and THz regime, the surface conductivity of graphene only comprises the contribution of intraband, and graphene has an effective dielectric function that can be described with the standard Drude model [27].…”

“…Medical Physics, College of Science, Zhejiang University of Technology, Hangzhou 310023, China 4. College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China.…”

Polarization properties of few-layer graphene on silicon substrate in terahertz frequency range

“…Currently, one of the relevant problems for development of THz photonics is the lack of efficient and affordable tunable under external influences devices for modulating the polarization of an electromagnetic radiation in the THz frequency range [11][12][13][14][15]. Polarization, amplitude, and frequency modulators are basic components in the security and telecommunication systems, for example, for communication between geostationary satellites.…”