A vector power coupling model for analyzing polarization-dependent loss of equilateral triangular 3×3 weakly fused fiber couplers

摘要

A rigorous power coupling model for weakly fused 3×3 triangular fiber couplers is proposed based on a full-wave surface integral equation method. In addition to the birefringence effect of the coupler considered in the proposed model, the influence of the state of the polarization (SOP) of the input light on the coupling behavior of the 3×3 triangular couplers can also be simulated. The accuracy of the power coupling model is checked by comparing with the experimental results. The agreement between them is reasonably good. The effect of fabricating parameters of the coupler, fusion degree, and heated length on the polarization-dependent loss (PDL) of the coupler is investigated by combining the Mueller matrix method into the power coupling model. It is found that the fusion degree is the dominant factor to influence the PDL performance of the coupler. The PDL significantly increases as the coupler is fused in weakly fused condition and the low-PDL coupler can be achieved by stronger fused couplers.