Tunable broadband terahertz metamaterial absorber using multi-layer black phosphorus and vanadium dioxide

We propose a dual-controlled switchable broadband metamaterial sandwich-structured absorber composed of black phosphorus (BP) and vanadium dioxide (VO2), suitable for operation in the terahertz range. The proposed absorber consists of multi-layered sinusoidally patterned BP, sandwiched between dielectric layers, and a VO2 bottom layer. Numerical results reveal that the broadband absorption can be dynamically tuned over a wide range by adjusting the electron doping of BP and conductivity of VO2. Owing to the fully metallic state of VO2, the proposed absorber realizes a more than 98% absorptance with the bandwidth of 2.9 THz under TE polarization and more than 90% absorptance with the bandwidth of 3.25 THz under TM polarization when the armchair direction of BP is along the y-axis and x-axis, respectively. Most importantly, by utilizing the dual independent controls in tandem, the state of proposed absorber can be switched from absorption (>98%) to reflection (>63.5%) while maintaining the broad bandwidth. Our research that utilizes the advantages of BP and VO2 presents a new perspective on the design of tunable broadband THz absorbers promising for potential applications such as switching, modulation, and sensing.