Plasmonic CH4 Sensor Based on MIM Waveguide Coupled to Circular Nanorod in a Square-Shaped Cavity

Abstract

A novel refractive index (RI) plasmonic sensor is designed and simulated, which is expected to make a significant advancement in gas sensing. The sensor is composed of silver, air-filled waveguide and a square shaped cavity. In the implemented cavity, 16 silver circular nanorods (CNs) are locally placed to enhance the sensing performance. Moreover, the cavity is filled with ultraviolet-curable fluoro-siloxane (UVCFS) in order to faithfully characterise methane gas concentrations. RI sensitivity (RIS) for Peak I is 1210.12 ± 4.62 nm/RIU and for Peak II is 969.64 ± 8.56 nm/RIU as well as figure of merit (FoM) of 20.00 ± 0.08 1/RIU at Peak I and 11.82 ± 0.10 1/RIU at Peak II, respectively. Furthermore, a significant methane gas sensitivity (S_Gas) is achieved: about 4 nm/% for Peak I and about 3 nm/% for Peak II which shows that it can well determine methane gas concentrations. The introduced plasmonic-based sensor brings potential applications in gas sensing due to its high sensitivity as well accuracy in detecting methane gas concentrations.