基于FDTD方法的光子晶体光纤色散特性分析

基于电磁场时域有限差分法(FDTD)计算光子晶体光纤(PCF)的方法, 分析了运用该方法时需要注意的一些问题, 特别是关于晶格位置、晶格上各个电磁场分量的分布以及完全匹配层(PML)中在边界处的电磁场的处理。以此为理论依据分析了一种纯石英材料双层芯PCF, 对这种光纤的传输特性进行了详细的数值模拟。通过调整光纤的结构参数, 设计出大负色散值的宽带色散补偿光子晶体光纤(DCPCF)。数值模拟结果显示在1530～1565 nm波长范围内其色散值在-400和-600 ps/(km·nm)之间变化, 达到了具有相同有效模面积的普通色散补偿光纤(DCF)的5倍。在整个C波段可以有效补偿长度25倍以上的标准单模光纤(SMF), 其色散剩余量在±1.0 ps/nm·km以内。该种结构的PCF对于制作高增益和宽带色散补偿于一体的集中式光纤放大器具有十分重要的意义。

Analysis of Dispersion Characteristic in Photonic Crystal Fibers Based on FDTD Method

A method based on finite difference time domain (FDTD) is applied to calculate the photonic crystal fiber (PCF). Some problems by using FDTD have been pointed out, especially the distribution of mesh and set to the properties of PML. A dual-concentric-core photonic crystal fiber based on pure silica has been analyzed by the proposed method. The transmission characteristic of such PCF has been deeply numerically simulated. By adjusting the structural parameters, we designed broadband dispersion compensating PCFs (DCPCFs) with large negative dispersion values. Simulation results show that the dispersion values vary between -400 and -600 ps/(nm·km) over the C band (from 1530 to 1565 nm), which is 5 times larger than the conventional dispersion compensating fibers (DCF) with nearly equal effective mode area. It can effectively compensate for the dispersion of 25 times of its length of standard single-mode fiber (SMF) with residual dispersion below ±1.0 ps/(nm·km) over the entire C band. It is very useful of such PCFs to be applied in leap optical amplifiers with high gain and dispersion compensation functionalities in a single component.