A simplified method to eliminate polarization induced distortion in dual Mach-Zehnder interferometry disturbance sensing system

In dual Mach-Zehnder interferometry sensing system, polarization induced phase distortion (including polarization induced phase shift (PIPS)) will lead to big location errors. By analyzing relationship of phase shift and polarization state (PS) of transmitted light, a simplified polarization control method using polarized light and a half-wave plate is proposed to eliminate PIPS. In this method, half-wave plate is the sole polarization control actuator, which simplifies the polarization control process, reduces time consuming and system cost, comparing to traditional polarization control method by using a three-wave-plate polarization controller (PC) or an opto-electrical PC. Experimental results indicate that the proposed method can increase the correlation of detected signals and obtain high positioning accuracy very well.