以二氧化硅为基材, 优化设计了一种圆空气孔六角点阵光子晶体光纤, 通过减小纤芯内层6个小空气孔以增加模场面积, 降低非线性系数. 采用时域有限差分法结合完美匹配层吸收边界条件, 对该光纤色散、非线性、约束损耗和基模模场与光纤结构参数之间的关系进行了数值分析. 结果表明, 该光纤呈现一定的超低损耗低非线性色散平坦特性, 其在最优结构参数下通信波长处的约束损耗小于10－7 dB·km－1, 在波长1.55 μm和1.31 μm处约束损耗分别为2.93×10－8 dB·km－1和7.33×10－10dB·km－1, 且波长从1.05 μm到1.65 μm色散值大约为0±1.7 ps·km－1·nm－1, 呈现双零色散点和较长波长范围的色散平坦特性. 在低损耗通信波长1.55 μm附近非线性系数约为4.88 km－1W－1. 该光纤呈现的超低损耗低非线性平坦色散能力, 可用于长距离大容量高速光通信系统.

A novel simple structure of photonic crystal fiber is optimized based on silica as the backing material, which has a cladding of hexagonal symmetric array uniform circle air hole and a larger the area of fiber core by missing central air column and reducing six air holes around the central core. Based on finite difference time domain method with the boundary conditions of anisotropic perfectly matched layers, its dispersion, nonlinear, confinement loss and fundamental mode field is numerically investigated. Numerical results indicate that the proposed fiber shows ultra-low loss, low non-linear and flattened dispersion performance. Its confinement loss is less than 10－7 dB·km－1 over communication band, which is 2.93×10－8 dB·km－1 and 7.33×10－10 dB·km－1 at wavelength of 1.55 μm and 1.31 μm, respectively. Furthermore, it appears double zero dispersion point and a certain ultra-flatten dispersion in the longer wavelength range, which flattened dispersion is 0±1.7 ps·km－1·nm－1 over 1.05~1.65 μm. Another, its non-linear coefficient is only 4.88 km－1W－1 at wavelength of 1.55 μm. It is obviously to obtained admirable application in the field of long distance high speed optical communication system due to its ultra-low loss low non-linear and flatten dispersion capability.