六角点阵蜂窝状包层光子晶体光纤中的高双折射负色散效应

High birefringence and negative dispersion effect of hexagonal honeycomb lattice photonic crystal fiber

设计了一种六角点阵蜂窝状包层光子晶体光纤,该光纤中心缺失一根空气柱形成纤芯,包层由椭圆空气孔和小圆空气孔组成.基于全矢量有限元法并结合各向异性完美匹配层边界条件,对其双折射、色散、非线性系数、约束损耗和模场等特性进行了数值模拟;计算了具有相同参数的椭圆状包层光子晶体光纤的双折射、色散及非线性系数.结果发现,若调整光纤结构参数为孔间隔Λ=1.15μm,空气孔椭圆率η=0.5,相对孔间隔比f=0.48,小圆孔直径d_1=0.4μm时,在波长1.55μm处,该光纤的双折射B高达1.02×10^(-2),比传统光纤高约两个数量级,同时,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,其色散斜率在整个C波段附近在-0.132—-0.121ps·km^(-1)·nm^(-2)范围内波动,非线性系数为45.7 km^(-1)·W^(-1),约束损耗接近10~2 dB·km^(-1).蜂窝状包层比椭圆状包层光子晶体光纤的双折射及大负色散特性明显提高,非线性系数低,更有利于进行色散补偿.

A novel hexagonal honeycomb lattice photonic crystal fiber is proposed, which is composed of a central defect core, a cladding with elliptical air-hole and small round air-holes. Based on the full vector finite element method with anisotropic perfectly matched layers, its birefringence, dispersion, nonlinearity, leakage loss and nlode field are numerically investigated. We compare hexagonal honeycomb lattice photonic crystal fiber and hexagonal elliptical lattice photonic crystal fiber, both of which have the same struc- ture parameters. Numerical results indicate that the proposed fiber shows high birefringence and negative dispersion effect. The birefringence is 1.02×10^-2, both its dispersion and dispersion slope are negative, the dispersion slope values are between -0.132- -0.121 ps·km^-1.n^m-2 over C band, the leakage loss is close to 102 dB.m^-1 and the non-linear coefficient is 45.7 km^-1·w^-1 at a wavelength of 1.55 μm, if the parameter is selected as A = 1.15 μm, η = 0.5, f = 0.48, and d1 = 0.4 μm. It is found that the hexagonal honeycomb lattice photonic crystal fiber easily obtains high birefringence, large negative dispersion and low non-linear coefficient. It is demonstrated that the hexagonal honeycomb lattice photonic crystal fiber has huge potential in designing dispersion compensation photonic crystal fiber.