Tunable plasmon-induced transparency absorbers based on few-layer black phosphorus ribbon metamaterials

Black phosphorus (BP) is a newfangled plasmonic material in the infrared region. We have achieved a mid-infrared plasmon-induced transparency absorption phenomenon via the excitation of BP surface plasmon by using a ribbon structure that contains symmetrical protrusions. The absorption efficiency can be significantly improved by adding a gold mirror at the bottom of the structure. The relative Fermi level can effectively adjust the absorption efficiency and wavelength. The symmetrical protrusions are connected with ribbons, and it is beneficial to the operation of the relative Fermi level. After that, the influence of the size of the symmetrical protrusions on absorption characteristics is researched. The results show that the absorption efficiency of the two absorption peaks reaches up to 75%. The angular dependence of the absorption of the system on the incident wave is discussed under the two orientations of the BP molecule arrangement relative to the structure. This structure can be implemented to realize a mid-infrared modulator, switch controller, and absorption device with three prominent functions.