Depolarization compensation in spun highly birefringent fiber with built-in half waveplate

Abstract

Nowadays, the spun highly birefringent single-mode optical fiber is increasingly being considered for current-sensing applications. However, when a broadband polarized light is launched into the fiber, apparent depolarization will occur with its propagation. This leads to a decrease in the polarization sensibility. In this paper, we propose a kind of method to compensate for the depolarization in spun highly birefringent fibers. An all-fiber half waveplate made of the helically wound spun highly birefringent fiber is placed at the center of the whole fiber. To obtain this half waveplate, the torsion of the helix should be equal to the inherent polarization rotation of the spun highly birefringent fiber. The advantages of the proposed method are simple, effective and without breaking the fiber. Simulations and experiments have demonstrated the excellent performance of the proposed method.