Simultaneous Beat-Length Measurement of a Polarization-Maintaining Few-Mode Fiber

Based on the polarization interference technique, we propose a modified method for simultaneously measuring the beat length of all guided modes in a polarization-maintaining few-mode fiber (PM-FMF). We experimentally demonstrate the effectiveness of our proposed method on a 3-mode PANDA-type PM-FMF. The simultaneous measurement results agree well with the results obtained by one-by-one measurement process. What's more, the modified measurement method is easier to be implemented and more scalable to a larger mode number.