Temperature Compensation Method for Polarization-Multiplexed Fiber-Optic Vibration Sensing Unit

Temperature cross-sensitivity, which especially performs complicatedly and severely in fiber-optic sensors composed of various materials, will significantly affect the stability and the accuracy of the parameter to be measured. Consequently, the polarization-multiplexed technology is introduced to separate the temperature and strain parameters, while a piecewise uniform compensation method is further proposed and employed to get rid of the nonlinear temperature effects in the fiber-optic vibration sensing unit (FOVSU). In the sensitive fiber coil (SFC) of the FOVSU, the solution interval of temperature coefficient is subdivided and employed for decoupling in different temperature ranges; then, the data are processed by splicing finally. The experimental results show that a suppression effect of temperature drift noise of 43 dB at 1 mHz is achieved under unidirectional self-cooling temperature conditions and 33 dB at 1 mHz under continuous temperature rise and fall conditions by using the piecewise method, which demonstrates that the performances in both situations are better than the original method using only one set of temperature coefficients. Therefore, the proposed new method could significantly reduce the temperature noise, leading to the testing accuracy and stability enhancement of FOVSUs.