Abstract
Fiber-optic Fabry-Perot (F-P) sensors are widely used in precision metrology, and their phase demodulation accuracy as well as long-term reliability strongly depend on the frequency stability of the light source. Traditional tunable laser schemes are simple and easy to operate, but they suffer from wavelength drift during long-term operation, which causes fluctuations of the demodulation noise floor and degrades the system stability in practical environments. To address this issue, we propose a three-wavelength phase-shift demodulation scheme based on an optical frequency comb (OFC). Exploiting the multi-tooth nature and high frequency stability of the OFC, we design a fiber-optic sensing scheme resistant to wavelength jitter and with potential for parallel demodulation, thereby suppressing the interference of wavelength jitter on demodulation accuracy at the source side. Comparative experiments with a tunable laser scheme are carried out to evaluate the system performance. Experimental results show that in the frequency band from 100 Hz to 2 kHz, characteristic signals are successfully demodulated, thus verifying the scheme’s effectiveness. Regarding noise suppression, the noise spectral level of the OFC system remains stable between -80 dB and -90 dB, whereas under the same conditions the noise floor of the tunable laser system exhibits significant drift over time. In summary, the OFC-based three-wavelength phase-shift demodulation scheme not only maintains signal detection capability but also significantly improves the system immunity against source wavelength disturbances, providing a new technical path for developing highly stable, multi-channel multiplexed fiber-optic F-P sensing demodulation technology.