Tunable and Broadband Coherent Perfect Absorption by Ultrathin Black Phosphorus Metasurfaces

TL;DR

This paper introduces a tunable, broadband, ultrathin coherent perfect absorber device using black phosphorus metasurfaces, operable in the terahertz range, with dynamic modulation capabilities and polarization insensitivity.

Contribution

It presents a novel BP-based bifacial metasurface design for broadband, tunable CPA in the THz range, enabling dynamic control and polarization versatility.

Findings

Achieves broadband CPA due to ultrathin design and BP properties

Enables dynamic modulation between CPA and transparency

Operates under various incident angles and polarizations

Abstract

Black phosphorus (BP), a relative new plasmonic two-dimensional (2D) material, offers unique photonic and electronic properties. In this work, we propose a new tunable and broadband ultrathin coherent perfect absorber (CPA) device operating in the terahertz (THz) frequency range. It is based on a bifacial metasurface made of BP patch periodic arrays separated by a thin dielectric layer. Broadband CPA bandwidth is realized due to the ultrathin thickness of the proposed device and the extraordinary properties of BP. In addition, a substantial modulation between CPA and complete transparency is achieved by adjusting the phase difference between the two counter-propagating incident waves. The CPA performance can be tuned by dynamically changing the electron doping level of BP. The CPA response under normal and oblique transverse magnetic (TM) and electric (TE) polarized incident waves is investigated. It is derived that CPA can be achieved under both incident polarizations and across a broad range of incident angles. The presented CPA device can be used in the design of tunable planar THz modulators, all-optical switches, detectors, and signal processors.