Fig. 1. Structure of the F-P interferometer cavity

Fig. 2. Sensing diaphragm. (a) Overall structure of the diaphragm; (b) structure is deformed by force

Fig. 3. Simulation of frequency response for rotation angle α. (a) Diaphragm rotation structure; (b) different angular frequency responses

Fig. 4. Combination of L-shaped cantilever of different lengths. (a) Schematic diagram of L-shaped cantilever structure; (b) effect of L-shaped cantilever length combination on sensitivity

Fig. 5. Simulation of diaphragm natural frequency and frequency response. (a) Resonance frequency simulation; (b) frequency response at different thicknesses; (c) frequency response at different widths

Fig. 6. Dimensions of π-shaped cantilever and rectangular cantilever. (a) π-shaped cantilever dimensions; (b) rectangular cantilever dimensions

Fig. 7. Frequency response curves of π-shaped cantilever and rectangular cantilever

Fig. 8. π-shaped cantilever sensor. (a) Structure of the sensor; (b) sensing diaphragm; (c) physical sensor

Fig. 9. Fiber optic acoustic sensor test experiment. (a) Schematic diagram of experimental system; (b) interferometric spectra of the sensor

Fig. 10. Acoustic response curves for different frequency acoustic signals. (a) Time-domain waveform of sensor; (b) corresponding frequency-domain waveform

Fig. 11. Frequency response curve of the sensor

Fig. 12. Sound pressure response of the sensor

Fig. 13. Signal at different volume fractions of acetylene. (a) Second harmonic signals; (b) peak fitting curve of the second harmonic signal