Optical Perfect Absorber Based On Graphene And Two-dimensional Black Phosphorus

Since the birth of two-dimensional materials,the related research based on twodimensional materials has gradually attracted the interest of many researchers due to its excellent physical and chemical properties,such as high electron mobility,good heat resistance and chemical stability.Thanks to the excellent properties of two-dimensional materials,the research of perfect absorber has also been rapidly developed.Compared to conventional absorbers,two-dimensional material-based absorbers can achieve adjustable,broadband,wideangle,insensitive to polarization states and perfect absorption of multiple channels.This paper mainly studies the perfect absorption based on several common two-dimensional materials,and has achieved some results.The main research contents of this paper are mainly divided into the following three parts:1.Perfect absorption of graphene based on Tamm plasmons: This section proposes to replace the traditional metal layer which can excite Tamm plasmons with graphene to achieve perfect absorption.Owing to the metal-like nature of graphene,it is possible to achieve perfect absorption by exciting Tamm plasmons.In addition,the Fermi level of graphene can be adjusted by changing the external voltage,which leads to the perfect absorption can be flexible adjusted.Compared to conventional plasmons,the excitation conditions of Tamm plasmons are simpler and do not require specific angles and polarization states,which results in the proposed perfect absorber with the properties of wide-angle and insensitive polarization states.In addition,multichannel perfect absorption can also be achieved by adjusting the thickness of the top layer of the structure.2.Coherent perfect absorption based on monolayer black phosphorus: This part mainly uses the interference of two beams of coherent light on a monolayer black phosphorus to achieve perfect absorption.We first analyze the conditions of coherent absorption from the propagation matrix of two beams of coherent light propagating in black phosphorus,and obtain the coherent absorption wavelength,and then at the coherence wavelength,the phase difference between the two coherent lights can be adjusted to obtain perfect absorption.The flexible adjustment of the absorption rate can be achieved by adjusting the phase difference.Due to the tunable band gap characteristics of black phosphorus,we can control the perfect absorption from the infrared band to the terahertz band by changing the concentration of the doping charge,while still maintaining excellent modulation depth.Finally,we analyzed the coherent absorption of different incident angles for the two polarization states.The results show that the coherent perfect absorption of monolayer black phosphorus is little affected by the polarization state and the incident angle.3.Perfect absorption based on graphene/one-dimensional topological photonic crystal: Here,a graphene/one-dimensional topological photonic crystal/Ag structure is designed to excite TPP mode and topological edge mode to achieve multi-channel perfect absorption.First,we removed the graphene from the structure,it appears a single peak perfect absorption.We theoretically explained that the perfect absorption is caused by the excitation of TPP mode.When graphene is added to the structure,the perfect absorption of the two channels occurs.By analyzing the field intensity distribution at the perfect absorption wavelength,it is found that the two perfect absorptions are caused by the topological edge mode and the TPP mode,respectively,and multi-channel perfect absorption by increasing the number of cycles of onedimensional photonic crystal.In addition,multi-channel absorption exhibits good angular selection characteristics.