Tunable Anisotropic Perfect Enhancement Absorption in Black Phosphorus-Based Metasurfaces

Bin Tang,Li Huang,Niegang Yang,Jiangbin Su,Chun Jiang

doi:10.1109/jphot.2020.2987157

Bin Tang, Li Huang + Show 3 more

Open Access

https://doi.org/10.1109/jphot.2020.2987157

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Abstract

In this work, we theoretically propose an anisotropic metasurface absorber, unit cell of which consists of a continuous monolayer black phosphorus (BP) sheet, sandwiched between a circular silver ring and a dielectric layer stacking on a silver substrate. Numerical results reveal that perfect enhancement absorption can be achieved in both armchair and zigzag directions, in which the resonant absorption peaks occur at different wavelengths due to the anisotropic property of BP. The calculated results by finite-difference time domain (FDTD) simulations have a good agreement with the coupled-mode theory. The physical mechanism of the perfect absorption is attributable to the critical coupling effect. Furthermore, the anisotropic perfect absorber not only exhibits tunable characteristics by varying the electron doping concentration, but also shows a wide-angle tolerance. In addition, our proposed absorber can achieve an arbitrary number of absorption bands by setting a suitable thickness of the dielectric layer. These results may have great potential applications in spectral imaging and photodetectors in the mid-infrared region.

Highlights

In recent years, black phosphorus (BP) [1], [2], as a newly emerging two-dimensional (2D) anisotropic material with atomic-scale thickness, has received increasing attention due to the intriguing chemical, physical and electronic properties
We theoretically propose an anisotropic metasurface absorber consisting of a continuous monolayer BP sheet sandwiched between a circular silver ring array and a dielectric layer stacking on a silver mirror, which can achieve nearly perfect absorption in both armchair and zigzag directions
Our proposed absorber can achieve an arbitrary number of absorption bands by setting a suitable thickness of the dielectric layer, which may have some potential applications in spectral imaging and photodetectors

Summary

Introduction

Black phosphorus (BP) [1], [2], as a newly emerging two-dimensional (2D) anisotropic material with atomic-scale thickness, has received increasing attention due to the intriguing chemical, physical and electronic properties. Qing et al proposed a perfect absorber by critical coupling of a monolayer BP with guided resonance of a photonic crystal waveguide slab to enhance light absorption at terahertz frequencies [27], and investigated the strong coupling of multiple resonance modes in a BP-hybrid system [28]. We theoretically propose an anisotropic metasurface absorber consisting of a continuous monolayer BP sheet sandwiched between a circular silver ring array and a dielectric layer stacking on a silver mirror, which can achieve nearly perfect absorption in both armchair and zigzag directions. Our proposed absorber can achieve an arbitrary number of absorption bands by setting a suitable thickness of the dielectric layer, which may have some potential applications in spectral imaging and photodetectors

Theoretical Model and Structural Design

Results and Discussions

Conclusions