Dual-channel surface plasmon resonance refractive index sensor based on modified hetero-core structure fiber

We propose and demonstrate a novel dual-channel SPR refractive index sensor based on hetero-core structure fiber. For the traditional hetero-core structure fiber SPR sensor, the resonance wavelength range is unchangeable. We solve this issue by polishing the traditional hetero-core structure fiber as circular truncated cone shape. By this method, we can adjust the resonance wavelength range flexible by changing fiber polishing angle. With increasing of fiber polishing angle, the resonance wavelength range will red-shift. When fiber polishing angle is 14°, and refractive index range is from 1.333 to 1.385, the resonance wavelength range is from 754 nm to 965 nm, which is away from that of the traditional hetero-core structure fiber SPR sensor (600 nm to 700 nm). Therefore, we realize dual-channel sensing by wavelength division multiplexing technology. The sensitivity of two channels are 1980.77 nm/RIU and 4057.69 nm/RIU respectively. In addition, the resonance wavelength and sensitivity of the sensor have a well consistency no matter which working way we adopt. The proposed dual-channel SPR sensor has important applications for multiple analytes detection.