非均匀光子晶体光纤光栅慢光的研究

Investigation on Slow Light in Nonuniform Photonic Crystal Fiber Gratings

利用改进的全矢量有效折射率方法结合耦合模理论和传输矩阵法,研究了高斯切趾和线性啁啾对光子晶体光纤光栅群时延的影响。结果表明:随着高斯切趾系数的增大,群时延最大值先增后减,即存在群时延最大的切趾系数。线性啁啾使得光栅群时延产生一段线性良好的区域,而且啁啾系数的绝对值增大时,群时延的线性区域扩大。但是,线性啁啾并不能使光栅在某一波段获得较小的群速度。高斯切趾可以有效调节最大群时延峰的带宽和高度,是一种有效调节光栅群速度的方法。

Based on improved effective index method,the coupled-mode theory and transmission matrix method,the influence of Gaussian apodizations and chirp coefficients on group delay of photonic crystal fiber Bragg gratings are demonstrated. The results indicate that the group delay first increases and then decreases when apodization coefficients increase,which means that the maximum value of group delay can be obtained at a given apodization coefficient. A good linear area of the group delay can be obtained by linear chirp gratings,and the linear area is broadened by increasing the absolute value of chirp coefficient. But linear chirp gratings don't get smaller group velocity in a particular band. Gaussian apodization is an effective way to tailor the group delay of fiber gratings,which can not only adjust the full width at half maximum but also influence the height.