Fig. 1. Schematic of the sensor. (a) Schematic of the fiber optic microphone; (b) design of the photoacoustic cell

Fig. 2. Simulated results of the photoacoustic cell at 101.325 kPa and 15 ℃. (a) Longitudinal resonant frequency of the photoacoustic cell versus its length and inner radius; (b) longitudinal resonant frequency versus temperature when the length is 100 mm and inner radius is 1.8 mm

Fig. 3. Output voltage of the microphone versus its resonant frequency

Fig. 4. Deformation of the first order resonant mode for the fiber optic microphone

Fig. 5. Fabrication process of the fiber optic microphone. (a) A mini FRM and the copper capillary tube wrapped with an ultra-thin fiber; (b) photoacoustic cell with inserted copper capillary tube; (c) left view of the fiber optic microphone integrated with the photoacoustic cell; (d) right view of the fiber optic microphone integrated with the photoacoustic cell

Fig. 6. Experimental setup of the fiber optic microphone integrated with a photoacoustic cell

Fig. 7. Output voltage response of the fiber optic microphone under the acoustic pressure of 0.1 Pa (100--5100 Hz). (a) 14^th June, 2020; (b) 15^th June, 2020

Fig. 8. Noise factor of the fiber optic microphone in a quiet condition

Fig. 9. Measured voltage sensitivity and acoustic pressure resolution of the fiber optic microphone versus the frequency. (a) 14^th June, 2020; (b) 15^th June, 2020

Fig. 10. Output voltage of the fiber optic microphone versus the amplitude of acoustic pressure at 1 kHz

Fig. 11. Dynamic range of the fiber optic microphone at 1 kHz