The impact of structural birefringence in multicore fibers

In this work we study the origin of birefringence in multicore fibers. With the help of simulations and experiments we are able to identify a new type of birefringence arising in multicore structures: structural birefringence. Hereby birefringence arises due to the intrinsic stress created by each core in the array and its value and orientation of the main polarization axis is dependent on the position of the cores in the array. We provide a comprehensive analysis of structural birefringence, and discuss ways to solve this problem.