针对大容量光纤通信系统, 设计了一种实用化的椭圆纯硅芯少模光纤, 给出了光纤的设计原理与参考标准, 运用全矢量有限元法结合完美匹配层边界条件分析了光纤的传输特性.在1.4~1.65 μm波长处, 光纤处于稳定的HE11和HE21双模运转, 模式有效折射率差大于1.8×10-3, 避免了模间耦合和串扰; 在工作波长1.55 μm处, HE11和HE21模的色散系数分别为19.61和4.41 ps/(nm·km),色散斜率分别为0.048和0.002 ps/(nm2·km),模场面积分别为97.17和143.96 μm2,模式的衰减系数均小于0.21 dB/km.该光纤的传输特性基本符合G.652和G.655光纤标准, 可利用现有成熟的“预制棒拉丝工艺”制备, 同时与波分复用技术相结合可以成倍提升光网络的传输容量, 对于下一代通信网络带宽的提升具有重要意义.

An practical few-mode fiber with elliptical pure SiO2 core was designed for large-capacity optical communication systems. The design principle and reference standard are presented, and the transmission properties were analyzed with full vector finite element method combined with perfectly matched layer boundary conditions. At the wavelength of 1.4~1.65 μm, the fiber is in stable dual-mode operation with modes HE11 and HE21, and the effective refractive index difference between the modes is greater than 1.8×10-3, which can avoid the mode coupling and crosstalk. At the wavelength of 1.55 μm, the chromatic dispersion of the modes HE11 and HE21 is 19.61 and 4.41 ps/(nm·km) respectively, the dispersion slope is 0.048 and 0.002 ps/(nm2·km) respectively, the mode field area is 97.17 and 143.96 μm2 respectively, and the attenuation coefficient of each mode is less than 0.21 dB/km. Transmission properties of the fiber can basically meet the G.652 and G.655 fiber standards, and it can be made by the existing mature “preform drawing” technology. This is significant for the promotion of next generation communication network bandwidth, which can be combined with WDM technologies to increase optical network transmission capacities exponentially.