用于级连EDFA增益谱平坦的滤波器透过谱设计的迭代算法

An Iterative Algorithm for Transmission Function Designing of Gain Flattening Filters

针对在两段掺铒光纤中插入滤波器实现宽带 (35nm)增益平坦的滤波器透过谱的设计问题 ,提出了一种新的迭代算法。其原理是利用放大器的均匀展宽特性和级连放大器自动增益补偿的特性。在每次迭代中 ,都取要求带宽内增益 (分贝数 )的平均值为参考轴 ,在增益比该轴高的波长范围内再附加一与增益谱反对称的损耗谱。而增益低于参考值的波长处则会得到自动的增益补偿。模拟计算结果表明 ,用该方法得到的滤波谱能使放大器的增益平坦在原放大器可能得到的最高增益水平 ,同时因滤波器的引入带来的噪声特性恶化也最小。

In broadband (35 nm) EDFAs, gain flattening filter can be inserted between the two stages of EDFs. In this paper, an iteration algorithm for designing the filter's transmission function is proposed. The principle of this algorithm is taking the advantages of homogeneous broadening and gain compensation between two stages. In each iteration step, the average gain level is taken as reference, and within the wavelength range where the gain is higher than the reference, an inverse gain spectrum is used to modify the transmission function. Then the gain within other wavelength range will be compensated automatically. Simulation results show that by using this iteration algorithm, the flattened gain can reach the possible highest value of the original amplifier, and noise penalty is the minimum.