Fig. 1. Working principle of double-beam thin-film interferometric fiber microphone based on phase demodulation

Fig. 2. Structural diagram of double-beam thin-film interferometric fiber microphone

Fig. 3. Principle of three-wavelength phase demodulation algorithm

Fig. 4. Outputs of double-beam thin-film interferometric fiber microphone based on phase demodulation under different signal frequencies. (a) 500 Hz; (b) 1000 Hz; (c) 2000 Hz

Fig. 5. Outputs of double-beam thin-film interferometric fiber microphone based on phase demodulation under different deviations of phase difference. (a) 5°; (b) 10°; (c) 15°

Fig. 6. Outputs of double-beam thin-film interferometric fiber microphone based on phase demodulation under different deviations of DC subentry and AC subentry. (a) 5%; (b) 10%; (c) 15%

Fig. 7. Experimental setup of double-beam thin-film interferometric fiber microphone based on phase demodulation

Fig. 8. Transmission spectrum of double-beam thin-film interferometric fiber microphone

Fig. 9. Test results of double-beam thin-film interferometric fiber microphone based on phase demodulation for different signal frequencies. (a) 500 Hz; (b) 1000 Hz; (c) 2000 Hz

Fig. 10. Frequency response of double-beam thin-film interferometric fiber microphone based on phase demodulation