Optimal design of cascading fiber ring depolarizers

The cascaded fiber ring depolarizer is proposed for the purpose of reducing polarization effects in fiber communication and interference sensor systems. Using recirculating loops, countless light components deposed by arbitrary round trips could finally be of random state of polarization (SOP) and mutually incoherent at the output by proper arrangement of lengths of fiber rings, so that the degree of polarization (DOP) approaches zero statistically. In this paper, the depolarization mechanism and key factors of cascaded fiber ring depolarizer are analyzed and discussed, and the performance is measured experimentally. Experiment result proves that optimized 10-fiber-ring depolarizers can work for a light with bandwidth of 1.6nm and gain a stable SOP-independent DOP of less than 2%.