设计了一种基于阿基米德螺线的新型螺旋光子晶体光纤, 该光纤以二氧化硅为基底材料, 包层由24个螺旋臂组成, 每个螺旋臂包含11个小空气孔, 纤芯设有大空气孔, 包层与纤芯中间的环形区域用于传输轨道角动量模式。该结构在1300~1800nm波段上可支持22种轨道角动量模式稳定传输, 在1550nm波长下, 有效折射率差最高可达 2.89×10-3, 色散系数最低可达 66.4ps/(nm·km), 非线性系数最低可达2.17W-1·km-1, 且1500~1600nm 波段上的色散值变化均小于15.15ps/(nm·km)。此螺旋光子晶体光纤不仅结构简单, 且具有低非线性、色散平坦的性能, 为螺旋光子晶体光纤的设计提供了思路。

利用多极法对光子晶体光纤的色散特性进行了模拟,通过结构参数的精确设计,得到了具有三个零色散波长的单模光纤,获得了色散值极低的超平坦色散曲线.对三个零色散波长光子晶体光纤特殊的相位匹配特性进行了研究,在不同光纤结构参数下,得到了相位匹配波长随抽运波长及抽运功率的变化规律,分析了不同色散曲线对应的相位匹配波长特点.三个零色散波长光纤能实现两个反常色散区之间光孤子的高效波长变换,可以获得6个新的四波混频相位匹配波长,产生更多光子对,为高效、多波长四波混频的产生及超连续谱的研究提供了新的物理环境.

The effective index of the cladding fundamental space-filling mode in photonic crystal fiber (PCF) is simulated by the effective index method. The variation of the effective index with the structure parameters of the fiber is achieved. For the first time, the relations of the V parameter of Yb³⁺-doped PCF with the refractive index of core and the structure parameters of the fiber are provided. The single-mode characteristics of large-core Yb³⁺-doped photonic crystal fibers with 7 and 19 missing air holes in the core are analyzed. The large-core single-mode Yb³⁺-doped photonic crystal fibers with core diameters of 50 μm, 100 μm and 150 μm are designed. The results provide theory instruction for the design and fabrication of fiber.

设计了一种宽带色散补偿光子晶体光纤，此光子晶体光纤在整个C波段具有较大的负色散值，且其色散斜率值均为负值。通过合理选取光子晶体光纤的层数和孔间距，同时优化各层的空气孔直径大小，分别设计了在1550nm附近的色散值为-425、-440和-400ps·km-1·nm-1；且色散斜率分别为-1.49、-4.31和-8.59ps·km-1·nm-2的宽带色散补偿光子晶体光纤。可以分别实现与G.652和G.655光纤的卡帕值和相对色散斜率相匹配，具有较好的宽带色散补偿能力。

When using normalized dispersion method for the dispersion design of photonic crystal fibers (PCFs), it is vital that the group velocity dispersion of PCF can be seen as the sum of geometrical dispersion and material dispersion. However, the error induced by this way of calculation will deteriorate the final results. Taking 5 ps/(km·nm) and 5% as absolute error and relative error limits, respectively, the structure parameter boundaries of PCFs about when separating total dispersion into geometrical and material components is valid are provided for wavelength shorter than 1700 nm. By using these two criteria together, it is adequate to evaluate the simulated dispersion of PCFs when normalized dispersion method is employed.

A simple method is presented to measure the transmission spectrum of hollow-core microstructured fibers in the visible, near-infrared, and mid-infrared regions. The plane wave expansion method is applied to analyze the photonic bandgaps of hollow-core microstructured fibers. The experimental results indicate that there are several strong transmission bands in the near-infrared and mid-infrared region, but hardly any transmission phenomena in the visible region, which shows that there are some bandgaps in near-infrared wavelength. The experimental results are consistent with the numerically simulative results using a plane wave expansion method.