Performance Comparison of Lossy Mode Resonance Refractive Index Sensors on Structures Based on Graphene and MoS2

Abstract

2D materials such as graphene and MoS2 play an essential role in improving the performance of optical sensors. This paper numerically investigates a lossy mode resonance (LMR) sensor that uses MgF2 as its matching layer. The transfer matrix method was chosen to determine the reflectance curve of LMR sensors with different thicknesses of MgF2 and 2D materials. The computational results show that the LMR sensor generated with s-polarized light has a better resonance. The existence of exciton in MoS2 also has a dominant contribution to the resulting resonance. There are two absorption peaks around the wavelengths of 610 nm and 652 nm, which are caused by the presence of excitons A and B in MoS2. When graphene and MoS2-based chips are compared, MoS2-based chips display a wider detection range with better signal stability. A sensitivity of 70.37°/RIU can be achieved with MgF2 (200 nm)/MoS2 (5 layers). In addition, the proposed LMR sensor has penetration depth that is 2 times higher than the conventional surface plasmon resonance (SPR) sensor, making it possible to replace SPR sensors that rely heavily on gold as their transducer.