Design and Simulation of a Highly Sensitive Plasmonic Sensor Based on Graphene and Black Phosphorus Strips

Abstract

In this article, a nine-layer hybrid plasmonic sensor structure based on a Kretschmann configuration is designed and simulated, comprising a graphene strip and two separate rows of black phosphorus strips with different widths of 110 and 70 nm. Unlike conventional configurations with a continuous layer of graphene and a single layer of black phosphorus, the dual plasmonic structure with induced transparency phenomenon and only one dark mode is achieved here by breaking the continuous symmetry and creating two independent dark modes. The results of numerical simulations show that the proposed structure is capable of creating two distinct transparent valleys at wavelengths of 7.2 and 8.8 μm in the absorption spectrum. With the increase in the refractive index of the medium from 1.33 to 1.40, these valleys shift to 90 and 110 nm, respectively. The figure of merit (FOM) is calculated to be 3.7 based on the two absorption peaks. The sensor designed for operation in biological environments with a high refractive index (~ 1.35) is optimized in the performance range of 1.33 to 1.40.