低损耗低非线性高负色散光子晶体光纤的优化设计

设计了一种同轴双芯六角点阵光子晶体光纤, 该光纤中心缺失一根空气柱形成内纤芯, 通过减小第4环空气孔的直径形成外纤芯. 采用全矢量有限元法并结合各向异性完美匹配层边界条件, 对其色散、非线性、约束损耗和模场等特性进行了数值模拟. 结果发现, 该光纤呈现高负色散可调效应和较强的模场约束能力, 约束损耗接近10^-2 dB· m^-1. 调整光纤结构参数(即空气孔间隔Λ, 小孔直径d₁和相对孔间隔比f), 可以控制其高负色散工作波长. 若调整光纤结构参数Λ=1.2 μ, f=0.917, d₁=0.515 μm时, 该光纤在低损耗通信窗口C波段呈现负色散和负色散斜率, 其色散斜率在-1----6 ps· km^-1nm^-2范围内波动, 在波长1.55 μm处负色散值为-3400 ps· km^-1nm^-1, 模场面积高达43 μm², 非线性系数仅有3.6 km^-1W^-1. 该光纤在C波段呈现的低损耗低非线性高负色散特性, 具有很好的色散补偿能力, 将在长距离大容量 高功率高速光通信系统中获得很好的应用.

Design and optimization of low-loss low-nonlinear high negative-dispersion photonic crystal fiber

A novel hexangular lattice dual-concentric-core photonic crystal fiber is proposed,which is composed of a central defect core, an outer ring core by introducing small air-holes on the forth ring and double cladding circle air-holes along the direction of fiber length.Based on full vector finite element method with anisotropic perfectly matched layers,its dispersion,nonlinear,leakage loss and mode field are numerically investigated.Numerical results indicate that the proposed fiber shows higher negative dispersion tunable effect and stronger confinement ability of guided mode,which the leakage loss is close to 10^-2 dB-m^-1.The wavelength for high negative dispersion value can be adjusted by artificially choosing the parameters of proposed fiber,i.e.A,d₁ and f.Both its dispersion and dispersion slope are negative,the dispersion slope values are between - 1--6 ps-km^-1 nm^-2 over C band,and its negative dispersion value is—3400 ps·km^-1nm^-1,the nonlinear coefficient is only 3.6 km-1W-1,and the corresponding area of mode field is 43μm² at wavelength of 1.55μm,if the parameter is selected as A = 1.2μm,f = 0.917,d₁ = 0.515μm.Obviously,it has a good dispersion compensation,therefore it has admirable applications in the field of high-speed large-capacity high-power pulses long-distance communication system.