论文部分内容阅读
EDFA的增益平坦化是WDM系统中的重要问题 ,用成本低、插损小的光纤光栅实现该功能是一项有吸引力的方案 ,采用剥层法设计了基于啁啾光栅的增益平坦滤波器。基于时间因果律的剥层算法将光纤光栅看成一个分离的模型 ,由一系列长度为Δ的复反射器所组成 ,每个反射器的后端耦合系数都可由它的前端耦合系数递归地求出 ,从而能快速、精确地反演出光栅的耦合系数函数。啁啾光栅的目标反射谱由理想的增益平坦滤波器透射谱获得 ,利用与反射谱群时延有关的常数α可控制光栅的长度 ,α取值为 0 0 0 2 4cm2 时 ,对应的光栅长度为 3 5cm。用剥层法反演出耦合系数函数后 ,又通过解Riccati方程模拟了合成光栅的透射谱。数值模拟结果显示理想透射谱与合成光栅透射谱之间的峰峰值误差小于 0 1dB ,并且在工作带宽范围内 ,透射谱群时延的变化量小于 0 6 ps ,表明该滤波器对系统没有额外的色散影响。
The gain flattening of EDFA is an important issue in the WDM system. It is an attractive scheme to realize this function by using a low cost and small insertion loss fiber grating. The peek method is used to design a gain flattening filter based on chirped grating . The stripping algorithm based on time causality considers the fiber grating as a separate model consisting of a series of complex reflectors of length A. The back coupling coefficient of each reflector can be recursively determined by its front coupling coefficient , Which can quickly and accurately reverse the grating coupling coefficient function. The target reflection spectrum of the chirped grating is obtained by the ideal transmission gain spectrum of the flattened filter. The length of the grating can be controlled by a constant α related to the reflection spectral group delay. When the value of α is 0 0 0 2 4cm2, the corresponding grating length For 3 5cm. After inverting the coupling coefficient function by peel-off method, the transmission spectrum of the composite grating was simulated by solving the Riccati equation. The numerical simulation results show that the peak-to-peak error between the ideal transmission spectrum and the transmission spectrum of the composite grating is less than 0 1 dB, and the variation of the transmission spectral group delay is less than 0 6 ps over the operating bandwidth, indicating that the filter has no additional system overhead The dispersion effect.