对圆芯型边孔光纤固有双折射的研究结果进行了报道。在对边孔光纤固有双折射的产生机理和计算原理进行研究的基础之上,采用有限元法分析了圆芯型边孔光纤的内部应力分布和双折射的大小。研究结果表明圆芯型边孔光纤的几何双折射较小,以应力双折射为主;边孔的存在导致光纤纤芯和包层区域的应力分布发生了较大的变化。文章提出了两边孔的连线方向为边孔光纤的快轴方向,并就不同的边孔结构对光纤双折射的影响进行了研究,发现圆芯圆孔型边孔光纤的固有双折射随边孔张角的增加而成指数关系增长,可通过增大边孔半径和减小两孔间距提高边孔光纤的双折射。

The research results of the intrinsic birefringence of the circular-core side hole fiber are reported. On the basis of the study on the production mechanism and calculation principles of the intrinsic birefringence of the side hole fiber, the finite element method is used to analyze the interior stresses distribution and the birefringence values of the circular-core side hole fiber. The research results indicate that the geometrical birefringence of the circular-core side hole fiber can be neglected, and the birefringence mainly relies on the stress birefringence; the stresses distributions in the core and cladding field have changed greatly because of the presence of the side holes. The conclusion is put forword that the fast axis of the circular-core side hole fiber is parallel to the link line of the two holes. The influence of different physical dimensions of the holes on the intrinsic birefringence of the side hole fiber is also discussed and the results show that the intrinsic birefringence of the circular-core side hole fiber with round holes increases exponentially with the angle of side holes. The birefringence can be improved through increasing the radius of the side holes and reducing the distance between the core and the side hole.