Fig. 1. Diagram of SPS fiber sensor structure

Fig. 2. Light path in curvature measurement experiment

Fig. 3. Transmission spectra of sensor after light passing. (a) Light directly passing; (b) light passing after employing Sagnac interferometer

Fig. 4. Spatial frequency spectrum of sensor when the length of PMF is 7 cm

Fig. 5. Interference spectra of curvature measurement for sensor when the length of PMF is 7 cm

Fig. 6. Linear analysis of sensor when length of PMF is 7 cm

Fig. 7. Round trip repeat test of sensor when the length of PMF is 7 cm

Fig. 8. Linear correlation contrast of sensors under different lengths of PMF