Dual-channel plasmonic refractive index sensor based on H-shaped optical fibres for multi-analyte detection

A highly sensitive multi-analyte detection technique with an H-shaped optical fibre-based surface plasmon resonance sensor is proposed using silver–gold nanowires (Ag–Au NWs). Ag and Au nanowires are deposited on two U-shaped grooves to excite the plasmon modes. As a result, the proposed plasmonic sensor realises dual-channel sensing. The amplitude and wavelength integration methods, as well as figure of merit, are utilised to investigate the sensor performance. The sensor performance and the coupling properties of the proposed plasmonic sensor are numerically analysed by using COMSOL Multiphysics based on finite element method. The proposed plasmonic sensor exhibits maximum wavelength and amplitude sensitivities of 4.0 and 10.5 μm/RIU, and 484 and 288 - 1 , respectively, for channel 1 and channel 2. The analyte RI changes from 1.33 to 1.40, corresponding to the RI resolutions of 2.5 × 10 - 5 and 9.09 × 10 - 6 RIU, respectively. Different structural parameters, such as diameter of (Ag–Au) nanowires, distance of channels from the core and channel width, are optimised to improve sensing response. The designed dual-channel sensor has potential applications in environmental monitoring and biosensing detection, owing to the highly sensitive multi-analyte detection and simple structure.