八边形低色散高非线性光子晶体光纤的设计

为了得到平坦色散高非线性的光子晶体光纤,设计了一种用于新颖的八边形三包层光子晶体光纤结构,采用多极法研究了空气孔直径、孔间距对色散和非线性的影响。结果表明,色散值和非线性系数随着内层空气孔直径d1的增大整体逐渐减小;随着第3圈空气孔直径d3的逐渐增大,色散值逐渐增大,但非线性基本保持不变;第2圈及外圈空气孔直径的变化对色散及非线性的影响较小。通过合理调节结构参量,在1.46μm～1.73μm近270nm波段内,色散绝对值在0.5ps/(km·nm)范围内波动;在1.5μm～1.65μm近150nm范围内的非线性系数值介于42.5W-1·km-1～50W-1·km-1。这一结果对设计特定功能的光子晶体光纤提供了理论参考。

Design of a novel octagonal photonic crystal fiber with flat dispersion and high nonlinearity

In order to obtain a new flattened dispersion photonic crystal fiber with high nonlinearity, a novel octagonal photonic crystal fiber(O-PCF) with three-cladding structure was designed. The effect of the hole size and hole space on the nonlinearity and dispersion of the PCF was analyzed by means of the multi-pole method. The result shows that the dispersion and the nonlinearity coefficient of O-PCF decrease with the increasing of the diameter of inner air hole. With the increasing of the diameter of the third air hole, the dispersion increases. Meanwhile, the nonlinearity coefficient almost remains constant. The dispersion and nonlinearity coefficient is affected little by the diameter of the second layer and peripheral air hole. By optimizing the diameters of the O-PCF holes and the hole pitch, an O-PCF with high flattened dispersion and nonlinearity was achieved. At the wavelength range of 1.46μm~1.73μm, the dispersion coefficient is merely changed within ±0.5ps／(km·nm), and the nonlinearity coefficient is merely changed from 42.5W-1·km-1 to 50W-1·km-1 at 1.5μm to 1.65μm. These results offer theoretical references for designing the photonic crystal fiber with some specific function.