Multi-Channel Seven-Core Fiber SPR Sensor Without Temperature and Channel Crosstalk

Biochemical processes are often very complex. Therefore, how to realize the monitoring of multiple biochemical parameters while eliminating the influence of ambient temperature change is always a challenging problem. For this purpose, using a seven-core fiber (SCF), we propose and demonstrate a multi-channel surface plasmon resonance (SPR) sensor, employing space division multiplexing (SDM) technology. The proposed SPR sensor has six sensing channels with the same structure. The cladding corresponding to the six side cores of the SCF is side polished and deposited with gold film to realize SPR sensing, and the fiber Bragg grating (FBG) inscribed on the central core is used for temperature sensing in each channel. We utilize SDM technology to independently detect each channel, effectively resolving the crosstalk issue often found in multi-channel SPR sensors. The measurements for proof-of-concept were made with glycerol aqueous solutions of different refractive indices (RIs), and the results indicated that the average refractive index sensitivity of the six channels is 2678 nm/RIU, 2636 nm/RIU, 2668 nm/RIU, 2623 nm/RIU, 2672 nm/RIU, 2653 nm/RIU in the RI range of 1.333–1.405 RIU, and the temperature sensitivity of each channel is about 9 pm/°C. The proposed sensor adopts the parallel multi-channel configuration, with flexible locations in each channel. As a result, the sensor enables remote quasi-distributed measurement and multi-analyte detection while eliminating the issues related to channel and temperature crosstalk. With its compact structure, low cost and easy preparation, this multi-channel SPR sensor has practical applications potential in biochemical detection, food production and environmental monitoring.