A Novel Demodulation Scheme of Fiber-Optic Interferometric Sensor Based on FM SSB Signal

A novel vibration signal demodulation scheme of fiber-optic interferometric sensor is proposed and demonstrated. A frequency-modulated (FM) single sideband (SSB) light-wave signal is generated by applying an FM microwave signal to a Mach-Zehnder modulator (MZM) for the demodulation of fiber-optic vibration interferometric sensor. A method of 12-sample orthogonal demodulation algorithm (ODA) based on setting the system sampling rate to 12 times of the FM frequency is adopted for the generation of two orthogonal signals for arc tangent transformation. The experimental results show that the harmonic distortion is well suppressed compared with the traditional phase generation carrier (PGC) arctangent (PGC-Arctan) algorithm, and a minimum detectable phase shift is achieved about 6.3 × 10
^-5
rad/√Hz at 5 kHz.