为了研究纤芯掺杂低折射率材料后三芯光子晶体光纤中任意两超模之间的模间色散特性, 采用全矢量有限元法进行了仿真, 取得了模间色散系数、零模间色散波长随纤芯折射率和结构参量变化的数据。结果表明, 通过调节纤芯折射率、纤芯直径、空气孔直径以及孔间距这4个结构参量, 可以使任意两超模间的模间色散在两个常用波段1.31μm和1.55μm处为0。该结果对于消除基于模分复用的光纤不同模式间因为模间色散导致的脉冲失真和实现零模间色散的模分复用技术是有帮助的。

In order to analyze the intermodal dispersion(IMD) between two random supermodes in a three-core photonic crystal fiber(PCF) with low refractive index material doping into the core, the intermodal dispersion coefficient and zero IMD wavelength as the function of core index and design parameters were investigated by using full-vector finite element method. The results show that zero intermodal dispersion can be achieved at two common wavelengths of 1.31μm and 1.55μm by adjusting the structure parameters, i.e., core index, core diameter, air hole diameter and the pitch of air holes. The result is helpful to eliminate the pulse distortion due to intermodal dispersion between different modes in PCFs based on mode division multiplexing and realize the zero IMD mode division multiplexing technology.