C波段具有平坦近零色散光子晶体光纤的一种改进设计方法

摘要

光子晶体光纤的最内层空气孔在拉制过程中容易发生形变,从而严重影响色散.基于多极法,模拟了当最内层空气孔为不易发生形变的较小值时,第二、三层空气孔对色散的影响,结果表明这种简单的色散控制方法也可以实现零色散点的快速平移,且保持色散平坦.以此为基础,设计了应用于C波段具有近零平坦色散的光子晶体光纤,色散系数为-0.24—0.33ps/（km·nm）.模拟表明,从第五层开始增加空气孔的层数对已设计光纤的色散影响很小,可以通过增加空气孔的层数得到理想的限制损耗.这一方法亦适用于S,L波段具有类似性质PCF的设计.%The innermost air holes of photonic crystal fibers deform easily during the draw process,resulting in serious influcence on the practical fiber dispersion.Based on the multipole method,the simulation in the paper only changes the air holes in the secondlayer and the third layer to adjust the dispersion,while the innermost air holes each are set to have a smaller parameter.The simulation shows that this simple dispersion control method can also make zero-dispersion point quickly move and keep the dispersion flat.Based on the detailed analysis,we propose C-band near-zero flat dispersion photonic crystal fiber with the dispersion coefficient varying from-0.24ps/（km·nm） to 0.33 ps/（km·nm）.Simulation shows that the air holes increasing from the fifth layer have little influence on the dispersion of previously proposed fiber,So by increasing the layers of air holes we can obtain an ideal confinement loss.This method is also applicable for the design of PCF operating in S and L bands with similar properties.