Fig. 1. Three-core tapered fiber SPR sensor

Fig. 2. Complex refractive index curves of high-purity indium

Fig. 3. Resonance spectra under different silver film thicknesses

Fig. 4. Resonance spectra of silver/high-purity indium films

Fig. 5. Resonance spectra under different structural parameters. (a) Resonance spectra under different sensing area lengths;(b) resonance spectra under different cone waist diameters

Fig. 6. Physical drawing of tapered three-core optical fiber

Fig. 7. Physical drawing of coated optical fiber

Fig. 8. Schematic of refractive index sensing and measuring experimental device

Fig. 9. Transmission spectra and fitting results of resonance wavelength and refractive index of silver plated SPR sensor. (a) Normalized transmission spectra; (b) fitting results of resonance wavelength and refractive index of solution

Fig. 10. Transmission spectra and fitting results of resonance wavelength and refractive index of SPR sensor with high-purity indium and silver film. (a) Normalized transmission spectra; (b) fitting results of resonance wavelength and refractive index of solution