中文摘要：

利用全矢量有限元法分析了光子晶体光纤（PCF）的结构参量对其本征模场分布的影响。数值计算结果表明,具有多层空气孔、多层纤芯、大孔间距和大占空比的结构更有利于将光场约束在纤芯中,纤芯层数、孔间距和占空比的增加均会导致PCF本征模场出现更高阶次的模式。纤芯层数和孔间距的增加会对由占空比减小所引起的功率泄漏进行一定的补偿,通过减小空气占空比、增加纤芯层数和孔间距,可实现大模场单模传输的可行性。对于4层空气孔、2层纤芯、占空比为0.01、孔间距为20μm的PCF,在保证单模传输的条件下,纤芯半径可达40μm,有效模面积为3717μm^2,纤芯功率集中度为68.32%。

英文摘要：

Effects of structural parameters of photonic crystal fiber （PCF） on its eigenmode field distribution are analyzed with the full vector finite element method （FEM）. The numerical calculation results show that light field will be confined in fiber core when the PCF structure is with multi-layer air hole and fiber core, long distance between air holes and large filling ratio of air. High order mode appears when the number of fiber core layers, distance between air holes and filling ratio of air increase. In addition, the increasing of the number of fiber core layers and distance between air holes compensates the power leaking at fiber core arising from the decreasing of filling ratio of air. It is demonstrated that the single-mode transmission with large mode field is feasible when we decrease filling ratio of air and increase the number of fiber core layers and distance between air holes. The core radius and effective mode area can reach 40μm and 3717 μm^2 respectively while the power concentration of fiber core is 68.32^ with four-layer air hole, two layer fiber core, air filling ratio of 0.01 and distance between air holes of 20 μm.