Fig. 1. Structure of optical fiber sensor and optical signal transmission(offset: dco=6 μm,SMF1 length: L=4 cm)

Fig. 2. Experimental setup for strain and refractive index measurement

Fig. 3. (a) Relationship between extinction ratio and SMF1 core-offset; (b) relationship between free spectral range and 1/L

Fig. 4. Near infrared transmission spectrum of optical fiber sensor (dco=6 μm, L=4 cm)

Fig. 5. (a) Strain transmission spectrum of optical fiber sensor;(b) relationship between interference dips of characteristic wavelength and strain

Fig. 6. (a) Transmission spectra of sensor under different refractive indexes; (b) relationship between interference dips of characteristic wavelength and refractive index