级联马赫曾德尔干涉仪滤波器可实现平顶化的滤波器频谱响应,但是利用传统的传输矩阵法,并不能方便地得到级联马赫曾德尔干涉仪滤波器中各耦合器的耦合系数。将级联马赫曾德尔干涉仪滤波器与数字信号处理中的有限脉冲响应滤波器进行了类比,并将数字滤波器的设计方法引入到级联马赫曾德尔干涉仪滤波器的设计中,将滤波器的传输函数表示成为各耦合器耦合系数的显式函数,同时利用遗传算法,计算了对于给定的滤波器频谱响应,级联马赫曾德尔干涉仪光滤波器中各耦合器的耦合系数。通过实例证明了利用数字滤波器的设计方法及遗传算法设计级联马赫曾德尔干涉仪光滤波器,不仅可以得到理想的结果,而且可以提高光滤波器的设计效率。

A cascaded Mach-Zehnder interferometer filter is used to construct a flat-top filter, but couplers' coefficients of the cascaded interferometer-based filter cannot be determined directely by the traditional transfer matrix way. An analogy between the cascaded Mach-Zehnder interferometer-based filter and the finite impulse response filter used in the signal processing is given, the transfer function of the filter can be explicitly expressed by the couplers' coefficients. Thus, some methods commonly used in digital filter design can be used to design the cascaded Mach-Zehnder interferometer-based filter. For a specified frequency response, the couplers′ coefficients of the cascaded interferometer-based filter are determined by the genetic algorithm. An example is given to verify the availability and efficiency of this method.