Tunable light trapping and absorption enhancement with graphene ring arrays

Abstract

Surface plasmon resonance (SPR) has been intensively studied and widely employed for light trapping and absorption enhancement. In the mid-infrared and terahertz (THz) regime, graphene supports tunable SPR via manipulating its Fermi energy and enhances light-matter interaction at the selected wavelength. Most previous studies have concentrated on the absorption enhancement in graphene itself while little attention has been paid to trapping light and enhancing the light absorption in other light-absorbing materials with graphene SPR. In this work, periodic arrays of graphene rings are proposed to introduce tunable light trapping with good angle polarization tolerance and enhance the absorption in the surrounding light-absorbing materials by more than one order of magnitude. Moreover, the design principle here could be set as a template to achieve multi-band plasmonic absorption enhancement by introducing more graphene concentric rings into each unit cell. This work not only opens up new ways of employing graphene SPR, but also leads to practical applications in high-performance simultaneous multi-color photodetection with high efficiency and tunable spectral selectivity.

Strong interaction between graphene and localized hot spots in all-dielectric metasurfaces

“…[49] The graphene over the all-dielectric metasurfaces can be modeled as a 2D sheet and the surface conductivity is governed by the random phase approximation (RPA) in the local limit. The 3 conductivity of graphene is related to the Fermi level E F and includes the interband and intraband contributions as follows, [50,51]…”

Dynamically Tunable Plasmon-Induced Transparency in On-chip Graphene-Based Asymmetrical Nanocavity-Coupled Waveguide System

“…Graphene, a monolayer of carbon atoms arranged in a two-dimensional (2D) honeycomb lattice [18], shows great potential for developing highly efficient optoelectronic devices due to its exceptional electrical and optical properties including the ability of extreme confinement [19–21], dynamic tunability, and relatively low damping losses [22, 23]. Particularly, the surface conductivity of graphene can be dynamically tuned by chemical potential via external gate voltage or chemical doping [24, 25], which makes graphene to be a promising candidate for designing tunable PIT while the geometrical parameters are fixed.…”

Dynamically tunable electromagnetically induced transparency analogy in terahertz metamaterial

“…In the THz regime, the complex valued surface conductivity of graphene can be modeled by the Drude-like expression, σ = ie 2 E F /(π 2 (ω + iτ −1 )), where e is the charge of an electron, E F is the Fermi level in graphene, is the reduced Planck's constant and τ is the relaxation time. [20][21][22] The relaxation time τ = µE F /(ev 2 F ) is dependent on the Fermi level E F , carrier mobility µ and Fermi velocity v F . 23,24 According to the experimental measurements, we set the Fermi velocity as 1.1 × 10 6 m/s, and the mobility as 3000 cm 2 /V·s in this work.…”