Random polarization effects on the dual M-Z fiber optic micro vibration sensor

The random polarization effects on the dual M-Z fiber optic micro vibration sensor was analyzed, and random polarization state resulting in the invalidation of time difference locating method was demonstrated. Random polarization state caused amplitude fluctuations of the two interferometric outputs and a-π-π phase difference between the two interferometric outputs. The phase difference made the dual M-Z fiber optic sensor working on two different working points, therefore the same phase modulation could generate two uncorrelated interferometric outputs. This could invalidate the time difference locating method, which was based on signal correlation. The analysis results was verified experimentally.