应用全矢量频域有限差分法,分析了所提出的一种高双折射光子晶体光纤的模式截止、损耗、模场半径及数值孔径等特性。数值模拟结果表明,通过设置合适的结构参量,可使这种高双折射光子晶体光纤在保持模式双折射为10-3量级的前提下,能够在600～1800 nm波长范围内保持单模传输,并且限制损耗可低于10-4 dB/m量级,同时还可以获得较大的数值孔径,因而聚光能力增强。此外,通过采用高斯曲线拟合基模的模场分布,得到的模场半径与实际模场半径吻合得很好。

The mode cutoff, confinement loss, modal radius, and numerical aperture of photonic crystal fiber (PCF) with high birefringence were analyzed by using full-vector finite difference frequency domain (FDFD) method. The numerical simulation results shown that, by choosing suitable structural parameters, the birefringence of the PCF may reach the order of 10-3 with broad single-mode region (600～1800 nm). A low confinement loss less than 10-4 dB/m and high numerical aperture can be obtained in a properly designed geometrical structure of PCF, so the focusing ability is enhanced. Moreover, by fitting the distribution of the fundamental mode using Gaussian curve, the obtained modal radius agrees well with the actual one.