Planar infrared double-layer black phosphorus tunable filter independent of polarization and with low angle of incidence dependence

Abstract

The anisotropic properties of monolayer black phosphorus (BP) allow the creation of plasmonic devices with directional-dependent properties. In this work, we propose an electromagnetic component based on BP for the THz and infrared regions, which is independent of polarization. The proposed device presents a periodic structure with a unit cell that consists of two square coupled BP layers with a thin dielectric sheet of h-BN between them. The two squares are rotated by 90^∘ with respect to each other. Such a structure provides a transmittance curve with one dipole resonant frequency regardless of the incident wave polarization. It is also characterized by a low dependence on the angle of incidence. The results are obtained by finite-element electromagnetic simulations and temporal coupled-mode theory. The suggested BP metasurface can be used as a dynamically tunable filter, switch, modulator, and sensor at frequencies much higher than those of the corresponding graphene structures.