Modeling Noise Transfer in Phase Demodulation Algorithm for Mach-Zehnder and Sagnac Hybrid Fiber Optic Interferometer

The Mach-Zehnder and Sagnac hybrid fiber optic interferometer (MZSI) is widely applied in numerous fields and capable of retrieving phase signals with the application of the appropriate demodulation algorithm. However, the performances of demodulation algorithms in MZSI are mainly evaluated based on empirical experiments. To address the lack of theory for selecting the optimal demodulation algorithm in MZSI, the noise transfer models of the differential cross multiplexing (DCM) and Arctangent (Atan) demodulation algorithms are investigated in both frequency and time domains. A novel analytical expression is proposed to characterize the noise transfer in the frequency domain, which accords with that in the time domain. The theoretical noise transfer models of the DCM and Atan demodulation are verified by simulation and experiment. The performance comparison between the DCM and Atan demodulation algorithms are conducted through the noise transfer models. It provides a reference for the selection of DCM and Atan demodulation algorithms in MZSI, which contributes to enhancing the demodulation performance of MZSI.