Microstructured Optical Fiber Based on Surface Plasmon Resonance for Dual-Optofluidic-Channel Sensing

A surface plasmon resonance (SPR)-based microstructured optical fiber (MOF) is designed and theoretically investigated for dual-channel optofluidic sensing. The design of the MOF consists of a solid silica core surrounded by double air holes, and the hollow section is coated with thin Ag film to excite the surface plasmon waves on the dielectric interface. The optofluidic sensing characteristics of the individual channel have been analyzed based on the mode-coupling theory between core and plasma modes. By filling the dual channel with different liquid analytes, the resonance wavelengths are adjusted away from each other to achieve dual-optofluidic-channel sensing. When the refractive index (RI) of liquid samples varies from 1.33 to 1.39 RIU, the optofluidic sensing sensitivities of channel 1 and channel 2 in MOF are 1439.29 nm/RIU and 4003.57 nm/RIU, respectively. The proposed SPR-based MOF is appropriate for multi-channel biological and chemical sensing fields.