Multi-layered graphene-phosphorene structures for tunable sensing in the mid-infrared region: a computational study

Abstract

This study presents a comprehensive computational investigation of multi-layered graphene-phosphorene structures for tunable absorption in the mid-infrared region (25–60 THz). Using Finite-Difference Time-Domain simulations, we explore the unique properties of asymmetric dark mode configurations in these structures. Our work introduces several novel aspects, including a systematic comparison of graphene and phosphorene as dark mode materials, revealing their distinct absorption characteristics and stability. We also introduce mixed-material structures, combining graphene and phosphorene dark modes to achieve tailored absorption profiles. Furthermore, we analyze dynamic tunability through Fermi level adjustment in graphene layers, demonstrating the potential for adaptive sensing applications. A detailed study on the impact of sample layer positioning on sensing performance provides crucial insights for optimizing refractive index sensors. We observe that structures incorporating diverse dark mode materials exhibit enhanced absorption peaks at higher frequencies. The asymmetric configuration allows for complex mode interactions, leading to the formation of multiple Fabry–Perot cavities and resultant absorption peaks. Our findings show that mixed-material structures can achieve sensitivities up to 14.13 THz/RIU with a figure of merit of 33.885 1/RIU, surpassing many existing designs. This work provides a foundation for designing advanced, tunable plasmonic sensors in the mid-infrared range, with potential applications in sensing.