Tunable anisotropic perfect absorption in hyperbolic metamaterials based on black phosphorous/dielectric multilayer structures

TL;DR

This paper presents a multilayer hyperbolic metamaterial using black phosphorus/dielectric stacks that achieves tunable, anisotropic perfect absorption in the infrared, with potential for polarization-sensitive applications.

Contribution

It introduces a novel BP/dielectric multilayer structure demonstrating tunable anisotropic absorption with angle-insensitive properties and adjustable via doping and geometry.

Findings

Achieves near-perfect absorption for one polarization

Impedance matching leads to critical coupling and perfect absorption

Absorption tunable through doping and geometric parameters

Abstract

Black phosphorus (BP) as a promising two-dimensional material with extraordinary optical properties constitutes an excellent building block in multilayer hyperbolic metamaterials. In this work, we design a multilayer structure composed of BP/dielectric layer stacking unit cells patterned on a gold mirror and theoretically demonstrate the tunable anisotropic absorption in the infrared regime. The electric dipole resonance between the adjacent unit cells drives the structure in the critical coupling state, and impedance of the structure matches to that of free space, showing the perfect absorption for one polarization direction, while the impedance mismatch for the other polarization direction leads to only 8.2$\%$ absorption at the same wavelength. The anisotropic absorption response of the proposed structure can be attributed to the intrinsic anisotropy of BP, which exhibits few dependence on the incident angle. Furthermore, we investigate the tunable optical absorption of the proposed structure with the electron doping of BP and the geometric parameters. These results demonstrate great potentials of BP in constituting multilayer hyperbolic metamaterials, and open up avenues in designing anisotropic metadevices with tunable spectral and polarization selectivity in the infrared regime.