设计了一种新型的光子晶体光纤(PCF)，使其能同时实现高非线性，超平坦色散和低损耗。通过基于全矢量有限元算法的模拟软件COMSOL，分析加了各向异性完美匹配层的八层空气孔光子晶体光纤的有效模场面积，色散特性以及光纤的限制损耗。数值模拟结果指出在波长1.55 μm处可获得36.2 W-1·km-1的高非线性系数。在1.37~1.70 μm共330 nm波长范围内，光子晶体光纤的色散值可达到(0.3±0.3)ps/(nm·km)，同时限制损耗在1.37~1.62 μm波长范围始终低于0.1 dB/km。

A simple design procedure is used to generate photonic crystal fibers (PCFs) with ultra-flattened chromatic dispersion. Only four parameters are required, which not only considerably saves the computing time, but also distinctly reduces the air-hole quantity. The influence of the air-hole diameters of each ring of hexagonal PCFs (H-PCF, including 1-hole-missing and 7-hole-missing H-PCFs), circular PCFs (C-PCF), square PCFs (S-PCF), and octagonal PCFs (O-PCF) is investigated through simulations. Results show that regardless of the cross section structures of the PCFs, the 1st ring air-hole diameter has the greatest influence on the dispersion curve followed by that of the 2nd ring. The 3rd ring diameter only affects the dispersion curve within longer wavelengths, whereas the 4th and 5th rings have almost no influence on the dispersion curve. The hole-to-hole pitch between rings changes the dispersion curve as a whole. Based on the simulation results, a procedure is proposed to design PCFs with ultra-flattened dispersion. Through the adjustment of air-hole diameters of the inner three rings and hole-to-hole pitch, a flattened dispersion of 0+-0.5 ps/(nm.km) within a wavelength range of 1.239–2.083 \mum for 5-ring 1-hole-missing H-PCF, 1.248–1.992 \mum for 5-ring C-PCF, 1.237–2.21 \mum for 5-ring S-PCF, 1.149–1.926 \mum for 5-ring O-PCF, and 1.294–1.663 \mum for 7-hole-missing H-PCF is achieved.

文章提出一种新型低损耗太赫兹波塑料光子晶体光纤(THz-PPCF)结构，其包层是由两种直径不同的空气孔周期性排列而成。利用时域有限差分法(FDTD)对其色散特性进行了分析。结果表明，通过调节包层中两种空气孔的直径以及晶格常数，可以得到低损耗、超平坦趋于零色散的太赫兹波塑料光子晶体光纤。

以多极法理论为基础,提出了一种阶梯结构的光子晶体光纤。通过改变其内四层的三个结构参量(内两层孔孔径,外两层孔孔径和孔间距),实现色散绝对值在1.1～1.8 μm 的波段内变化仅为0.05～2 ps/(km·nm)的平坦甚至超平坦的特性。在此情况下对其有效模场面积进行数值模拟,充分展示了达到色散平坦和超平坦时,相对于传统光子晶体光纤,此种结构的光纤对芯区内光场的局域能力有很大程度的增强,其有效模场面积可仅为传统光子晶体光纤的1/30。最后,经过大量的数值计算和理论分析,归纳出若要此种阶梯结构的光纤在1.1~1.8 μm的波段内达到色散平坦甚至超平坦特性的设计依据。

提出了一种复合六边形空气孔格点光子晶体光纤,其包层是由两种不同大小的空气孔组合而构成的。利用带有良匹配层(APML)吸收边界的全矢量频域有限差分法(FDFD)对其色散特性进行了数值分析。结果表明,通过调节包层中两种不同尺寸的空气孔的大小以及孔间距这三个参量,可以得到不同水平的平坦色散曲线,甚至超低超平坦的色散曲线。在孔间距Λ取2.1 μm,小尺寸空气孔直径取0.5 μm, 大尺寸空气孔直径取0.8 μm的条件下,在1.48～1.78 μm的波长范围内得到了0±0.545 ps/(km·nm)的色散。

利用有效折射率方法的标量近似理论对三角排列的光子晶体光纤超平坦色散特性进行了理论分析和数值模拟，研究发现改变光子晶体光纤包层空气孔半径或空气孔间距可以改变波导色散的特性，从而可以设计在不同波段，不同大小值的超平坦色散。本文的计算和分析可以为设计不同色散特性的光子晶体光纤提供理论依据。