椭圆六角分布微结构光纤中的双折射

Birefringence in Squeezed Hexagonal Lattice Microstructure Fiber

利用全矢量有限元方法,对椭圆六角对称分布微结构光纤(MF)的双折射特性进行了理论分析,得到了双折射大小与结构参量、入射波长间的依赖关系。分析表明:合理设计结构参量可得到10-3量级大小的双折射;微结构光纤的双折射对光波波长极其敏感,并出现随波长变化快慢轴交换的现象。采用统计的方法对双折射与微结构光纤空气孔直径随机变化的统计相关性进行了理论分析,假定空气孔直径为高斯分布,获得了双折射大小的平均值和标准偏差与随机变化孔径的统计关系。结果表明,由孔径分布不规则所产生的双折射的大小主要取决于空气孔直径的平均值。

Based on the full-vector finite element method, the birefringence in microstructure fiber with squeezed hexagonal lattice is numerically analyzed. The correlation between the birefringence and the structural parameters, incidence wavelength is obtained. The numerical results show that the birefringence is sensitive to wavelength, and can be achieved by a magnitude of 10^-3 with a proper design and the fast and slow axes can swap as incidence wavelength is changed. To simulate the practical situation, each air hole diameter is assumed with a Gaussian distribution. The birefringence is found to be largely dependent on the variation of air hole diameter. In the statistical analyses, the correlation between the variation of air hole diameters and the birefringence in such microstructure fiber is obtained. One important result is that the non-intentional birefringence depends on the mean air hole diameter, and a increase of the size of the fiber structure the birefringence.