Stress birefringence in the three-core optical fiber and its effects on the transmission property

•Stress field distribution characteristics in the three-core optical fiber are analyzed.•Effective method to extract stress induced birefringence in the fiber is acquired.•Three-core optical fiber with ultra-low PMD is found and its parameter is present. This paper investigates the stress field distribution characteristics in the three-core optical fiber. Utilizing Fourier transform analysis of the stress tensor components, it is shown that the constant part in the stress tensor, or the overall elevated value of the oscillation curve, is directly related to the stress induced birefringence. So, an effective method to extract information about stress induced birefringence is acquired. The polarization mode dispersion (PMD) and the relationship between stress induced birefringence and the structural parameter of the optical fiber are investigated by numerical simulation. It is found that the PMD usually decreases with the increase of the distance from the core to the fiber center. And it even reaches zero at a certain distance; while increases again thereafter. Some three-core optical fibers with ultra-low PMD and high transmission rates are designed based on these results.