Fabrication method and sensing characteristics of SPR sensor with helical-core fiber
A method of adjusting the resonance wavelength by changing the incidence angle is provided by prism-based Surface plasmonic resonance(SPR)sensing systems,but it is difficult to achieve this adjustment method for optical fiber SPR sensors.Therefore,a SPR sensor based on side-polished helical-core fiber(HCF)is proposed.HCF is made by twisting the eccentric fiber.Two kinds of SPR excitation methods,cladding Whispering gallery modes(WGM)and fundamental mode of the core,are studied in detail.The results show that the resonance wavelength of the SPR sensor can be effectively adjusted by changing the pitch of the HCF.When the refractive index of the measured medium is 1.333 0～1.375 2,the average sensitivity of the sensor with a pitch of 1.40 mm can reach 5 800 nm/RIU,and the sensitivity can be further improved by using a smaller pitch HCF.According to these characteristics,SPR sensor arrays can be prepared on the same HCF or multi-core HCF with different pitch for multi-parameter measurement,which will be widely used in chemical and biochemical sensing fields.
helical-core fiberSPR sensorfiber fusion twistingfiber side polishing
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