High-resolution interrogation of FBG-based inclination sensor with microwave photonic filtering technique

This paper focuses on a multi-point inclination sensing system composed of fiber Bragg grating (FBG)-based inclination sensors. A high-resolution demodulation method is introduced, employing the microwave photonic filtering technique. The system’s frequency response is processed through a frequency-to-time domain transformation, which effectively maps the FBG wavelength into the time domain. This method enables the measurement of the time interval between the two FBGs, facilitating high-precision demodulation of both the tilt angle and direction. Moreover, the system effectively eliminates the influence of temperature fluctuations on inclination measurements. Experimental results demonstrate that the system achieves an inclination measurement sensitivity of 17.806 ps/° within a range of ±10°, with a resolution of 0.023°.