Multi-channel SPR sensor based on the cascade application of the Single-mode and multimode optical fiber

We propose and demonstrate a multi-channel SPR sensor based on the cascade application of the single-mode and multimode optical fiber. At this article, we studied the relationship between the gold film thickness and the sensing performance of the multimode fiber-based SPR sensor, the larger is the gold film thickness, the longer is the resonance wavelength, and the better is the sensitivity. We also studied the relationship between the grinding angle of the single mode optical fiber and the sensing performance of the single mode fiber-based SPR sensor, the larger is the grinding angle, the longer is the resonance wavelength, and the better is the sensitivity. Based on the above research, the reflected light of the single mode fiber-based SPR sensor is injected into the multimode fiber, and the multi-channel fiber-based SPR sensor is realized by fabricating transmitted SPR sensor on the multimode fiber. We realize the designable dynamic range adjustment by the cascade application of the single-mode and multimode optical fiber, and the sensitivity keeps constant. When the thickness of the gold film on the multimode fiber is 35 nm and the grinding angle of the single mode fiber is 16 (the gold film on the single mode fiber has a fixed thickness of 50 nm), the sensitivity of the two sensing zone on the multi-channel SPR sensor reach 2115 nm/RIU and 5212 nm/RIU respectively.