Near-unity broadband infrared absorption in a graphene-black phosphorus bimodal triple-layer structure

It is well known that both graphene and monolayer black phosphorus (BP) can excite and generate surface plasmonic resonances in the infrared spectrum, providing suitable conditions for strong light-matter interactions. To take full advantage of this benefit, a three-layered infrared absorbing structure with broadband absorption effect based on a hybrid graphene-BP metamaterial was developed. Using numerical research methods, the absorption effect of the structure could be well modulated by adjusting the geometrical parameters of the structure and the doping levels of graphene and BP. In addition, the sensitivity of the structure to the angle of incidence is also investigated. By optimizing the previous parameters, the structure achieves an absorption of more than 87.5% in the wavelength range from 10.1 to 24.5 um and a maximum absorption of 99.97%. The proposed broadband infrared structure could have many potential applications in infrared sensing, bio-imaging and environmental monitoring.