Theoretical analysis of feedback control on input light polarization of fiber optic interferometer

Demodulated by fiber optic Mach-Zehnder interferometer which has longer unbalance length,the sensing signal of DFB laser experiences the polarization induced fading.The feedback control scheme of interferometer input light polarization is introduced,which can be used to overcome the polarization induced fading.The interferometer signal demodulation system is discussed in detail,which has feedback control function.The relation between control signal and interferometer stripe visibility is deduced.The working process is analysed at different signal input condition.Theoretically the interference stripe visibility can be stabilized nearby 1 under a certain condition.The feedback control scheme can be used to eliminate the polarization induced fading.