Dual-channel step multimode fiber SPR sensor based on sawtooth structure

The fiber SPR sensor with a single sensing channel can not detect multiple analytes at the same time and introduce the reference channel to eliminate nonspecific interference. Hereby we proposed a sawtooth dual-channel fiber SPR sensor based on WDM technology. By CO2 laser, multiple V-shaped grooves are processed on the step multimode fiber to form a sawtooth structure. The first stage of the sensor was fabricated by coating gold film on the sawtooth area, and the second stage was fabricated by coating gold film on the cladding area 2 cm behind the sawtooth area. The sensitivity and dynamic range of the two channels are 3114.86 nm/RIU and 1584.23 nm/RIU, 719.93 nm-854.2 nm, and 584.24 nm-667.62 nm, respectively. The proposed fiber SPR sensor employs the sawtooth structure to adjust the SPR resonance wavelength, so as to realize dual-channel sensing, which is of significance in the fields of simultaneous detection of multiple analytes and temperature compensation of reference channels.