Simulation of Multiple Optical Fiber Structures as Refractive Index Sensor

Optical fiber technology, prized for its lightness, compact nature, resistance to electromagnetic interference (EMI), and corrosion resistance, has been compelling and widely adopted, particularly in sensing applications. Nevertheless, the use of multiple optical fiber structures such as Single-Mode Fiber (SMF) and Multi-Mode Fiber (MMF) in sensing applications necessitates complex fabrication steps. To address this limitation, No-Core Fiber (NCF) has emerged as a promising alternative, owing to its unique fiber characteristics. Hence, this paper demonstrates a simulation-based analysis for different fiber structures including SMF, MMF and NCF to evaluate their refractive index (RI) changes in responding to the surrounding environment (analytes) ranging from 1.30 - 1.40 RIU based on evanescent wave sensing principle. The simulation is conducted by utilizing the Wave Optics Module of COMSOL Multiphysics software. The best fiber structure is then assessed for a higher range of refractive index variation from 1.46 - 1.56 RIU to observe the leaky mode attenuation. The simulation results show that NCF exhibits significant variations in the evanescent waves, providing a clearer view of their presence at the analyte boundary for lower and higher ranges of RI. This observation substantiates the potential of NCF as a highly sensitive sensor for sensing applications, especially when compared to SMF and MMF, as it is directly exposed to the analyte boundary.