Fig. 1. Schematic diagram of the proposed EFPI.

Fig. 2. Microscope images of the (a) fiber end face A, (b) fiber end face B, and (c) whole assembly.

Fig. 3. Experiment setup of RI sensing.

Fig. 4. Spectrum of the EFPI in air.

Fig. 5. Spectra of the EFPI filled with a NaCl solution (5%–10%).

Fig. 6. Amplification of part of the spectra.

Fig. 7. Wavelength shifts versus RI for the EFPI.

Fig. 8. Spectrum of the sensor in water with a cavity length of 358.5 μm.

Fig. 9. Wavelength shifts for the sensor with a cavity length of 358.5 μm.

Fig. 10. 11×81 values of the demodulated cavity length Lf.

Fig. 11. Cavity length Lf variations versus RI for the EFPI.

Fig. 12. Cavity length Lf variations versus temperature, from 30°C to 60°C.