Research on polarization control in the long distance fiber-optic sensing

The long distance fiber-optic sensing system based on Mach-Zehnder interferometer has been widely used in many fields. We discussed the polarization signal fading caused by the birefringence property of the fiber. Research results show that, due to the birefringence effect of long distance fiber-optic sensing, when incident light polarization state changes, the output power will change which causing interference signal changes. This phenomenon is called "polarization-induced signal fading". In order to eliminate polarization fading in long distance fiber-optic sensing, add the system with polarization controller to adjust light polarization state, can get a good visibility of interference signal.