Distributed Measurement of Polarization Mode Coupling in Polarization Maintaining Fibers Using Microwave Photonic Filter Technique

Polarization mode coupling (PMC) is a detrimental effect that limits the polarization maintaining performance of polarization maintaining fibers (PMF). In this paper, we propose and demonstrate a novel method based on a principle similar to that of a microwave photonic filter (MPF) for the PMC distribution measurement. By regarding the PMF with PMC taking place as an MPF and measuring its transfer function in frequency domain, we are able to identify the intensities and locations of PMC events along PMFs. After detailed theoretical analysis and numerical simulations, validation experiments have been conducted on four PMF segments with rotational splicing between each other to manually generate PMCs. The measurement results of PMC positions and strengths are in accordance with the preset values. With a frequency scanning step of 16 MHz and a range of 14.4 GHz, such method can achieve a spatial resolution of 30 m and a measurement range of 27 km. The proposed method is suitable for the measurement of PMCs along PMFs up to tens of kilometers.