Towards Mirror-Less Graphene-Based Perfect Absorbers

Abstract

Owing to its exceptional electronic and optical properties, graphene has attracted extensive attention among researchers in the development of high-performance optoelectronic devices. However, the light absorption of pure graphene is very poor, limiting its development in practical application. In this review, as a solution for this issue, various types of graphene-based perfect absorbers are addressed in terms of their operation principles and design requirements. Their recent progress and potential applications such as photodetectors and modulators are also discussed. In particular, we emphasize the importance of mirror-less (in particular, one-port mimicking) perfect absorber design due to simplified fabrication processes or enhanced tolerance for fabrication error.

Tunable High-Sensitivity Four-Frequency Refractive Index Sensor Based on Graphene Metamaterial

“…The effect of graphene’s relaxation time on the absorption spectrum is explored below, beginning with the relaxation time (an important graphene property), using this expression [ 51 , 52 ]: where and are the chemical potential and carrier mobility of graphene, respectively, e represents the charge of the meta-charge, and V F is the Fermi velocity of graphene, which can be calculated as , according to the simple energy band theory.…”

Cutting nanodisks in graphene down to 20 nm in diameter

“…In particular, 2D nanomaterials with heavy metal atoms like MoS 2 can be a better choice to limit the vaporization phenomenon observed on graphene. Considering now how to use the obtained nano-hole in graphene, our process can be also used to fabricate metal-surface [26] and grating [27]. In this direction, new 2D materials like black phosphorus [28,29] are also of interest for HIM milling.…”

Perfect Absorption and Reflection Modulation Based on Asymmetric Slot-Assisted Gratings without Mirrors

“…Recently, our research group has introduced a novel approach inspired by the concept of a one-port system mimicking, leading to the development of some mirrorless perfect absorbers. These absorbers are based on an asymmetric single resonator supporting two degenerate resonant modes, in which only one mode experiences loss while the other mode acts as an internal reflector in conjunction with background scattering [22][23][24][25]. The asymmetric resonator can be easily implemented with a vertically asymmetric slab-waveguide grating (SWG) [22][23][24][25].…”

“…These absorbers are based on an asymmetric single resonator supporting two degenerate resonant modes, in which only one mode experiences loss while the other mode acts as an internal reflector in conjunction with background scattering [22][23][24][25]. The asymmetric resonator can be easily implemented with a vertically asymmetric slab-waveguide grating (SWG) [22][23][24][25]. In this approach, a guided-mode resonance (GMR), which is of a relatively low-quality factor, was employed to function as the internal mirror, and the other resonant mode, which is responsible for absorption and of a relatively highquality factor, could be another GMR mode of a higher diffraction order [22,23] or a quasibound states in the continuum (quasi-BIC) [24,25].…”

“…The asymmetric resonator can be easily implemented with a vertically asymmetric slab-waveguide grating (SWG) [22][23][24][25]. In this approach, a guided-mode resonance (GMR), which is of a relatively low-quality factor, was employed to function as the internal mirror, and the other resonant mode, which is responsible for absorption and of a relatively highquality factor, could be another GMR mode of a higher diffraction order [22,23] or a quasibound states in the continuum (quasi-BIC) [24,25]. When a high-order diffraction GMR mode is employed, it is required that the index of the substrate should be lower than half of that of the grating (i.e., nSWG > 2nSub).…”