Fig. 1. Schematic diagram of optical fiber liquid/gas pressure sensing

Fig. 2. Schematic diagram of multiple Fabry-Perot cavities

Fig. 3. Simulation results of the relationship between L_x and P_w

Fig. 4. Pressure testing system diagram

Fig. 5. Sensor gas pressure testing. (a) Reflection spectra of the sensor at different gas pressures; (b) pressure response of sample at different wavelengths

Fig. 6. Sensor temperature response testing. (a) Interference spectra at different temperatures; (b) wavelength shift variations of different dips

Fig. 7. Dynamic change of liquid surface curvature under different pressures. (a) Microscopic photos of capillary column under different gravity directions (the arrow in the illustration indicates the gravity direction); (b) experimental results of arc height Δx under different pressures

Fig. 8. Sensor hydraulic testing. (a) Reflection spectra of the sensor under different hydraulic pressures; (b) FFT spectrum of the reflection spectrum; (c) filtered spectra after the first dominant frequency peak; (d) filtered spectra after the second dominant frequency peak

Fig. 9. Sensor hydraulic performance testing. (a) Hydraulic response and error analysis of sensor cavity length; (b) temperature response of the sensor (P_w=9 kPa)