Ultrahigh-speed phase demodulation of a Fabry–Perot sensor based on fiber array parallel spectral detection

An ultrahigh-speed phase demodulation system was designed for the Fabry–Perot (F–P) interferometric sensor based on fiber array parallel spectral detection. A high-power amplified spontaneous emission (ASE) source served as the broadband detection light. The spectrum generated by the dispersion of the F–P interference light through an arrayed waveguide grating (AWG) was incident into the fiber array and was detected in parallel by 48 photodiodes. The 48-channel signals were acquired synchronously and processed in real time to achieve a phase demodulation for the F–P cavity at 200 kHz. As a result, a low-resolution spectral detection and demodulation system was constructed with high speed. The length demodulation range of the F–P cavity was 60–700 µm, and the demodulation resolution was as high as 0.22 nm. The designed high-sensitivity demodulator is expected to be used for ultrasonic and high-frequency vibration detection.