基于时延纹波和带宽均衡的啁啾FBG切趾选择

Chirped FBG Apodization Selection Based on a Balance between Time Delay Ripple and Bandwidth

文章提出一种新颖的切趾选择方法用以简化啁啾光纤布拉格光栅(C-FBG)的切趾选择。该方法基于光栅切趾后带宽会和群时延纹波(GDR)一起减少的矛盾,指出能使光栅带宽变化量尽可能小和群时延纹波减少量尽可能大的切趾即是最佳切趾。利用该方法,数值实验对比了五种常见切趾函数的切趾效果,并考察了光栅长度、周期、啁啾和折射率变化量对切趾效果的影响。结果表明:余弦、双曲正切和柯西三种函数切趾效果优于高斯和汗明函数;而光栅长度、啁啾和折射率变化量等三种光栅参数会对切趾效果产生明显影响,这种影响可以作为光栅参数选择的依据。

Apodizafion is a crucial technology for improving the dispersion performance of fiber Bragg gratings （FBG）. A novel apodization selection method is demonstrated to simplify the apodization selection of chirped fiber Bragg gratings （ C - FBG）. The method based on the conflict between the FBG bandwidth and the average group delay ripple （GDR） considers the apodization that can minimize the bandwidth change and maximize the GDR reduction to be the op- timal apodization. And a apodization performance distance is defined to measure the apodization performances of different profiles. Experiment shows that the method can select an optimal apodization profile and parameter for chirped FBGs easi- ly and accurately compared with other approaches because it makes a selection via only two parameters - bandwidth and GDR. The numerical experiments based on the method exhibit the different performances of five different apodization profries and evaluate the influence of FBG parameters such as grating length, period, chirp, and index change on the apedization performance. The experiment results show that the apodization performances of the cosine, tanh and Cauehy pro- files are better than those of the Gauss and Hamming profiles, and the apodization performance could be noticeably influenced by the grating length, chirp, and index change, these influences can be used as a foundation for FBG parameters selection.