为改善全光纤三信道波长交错器的输出特性，提出了一种不对称结构的三光纤臂Mach-Zehnder干涉仪(A-MZI)，这种光纤干涉仪由一个一字型3×3 单模光纤耦合器和一个品字型3×3 单模光纤耦合器以及三条光纤干涉臂组成，其中一字型3×3 单模光纤耦合器作为输入耦合器，品字型3×3 单模光纤耦合器作为输出耦合器。推导了该器件的输出表达式，并进行了数值模拟。模拟结果表明，与常规的全光纤MZI型三信道波长交错器(C-MZI)相比，本文提出的交错滤波器的信道间功率旁瓣降低了约13.6 dB，并且具有对器件参数偏差不敏感等优点。用光纤熔融拉锥法实验制作了该器件，实验结果与理论分析吻合得很好，实验样品的信道间功率旁瓣值<－34.6 dB, 插入损耗< 1.0 dB，信道隔离度>30 dB。

In order to improve the transmission performance of the all-fiber three-channel interleaver, a novel asymmetrical structure of a Mach-Zehnder interferometer(A-MZI) with three fiber arms is proposed. The A-MZI consists of a fused planar 3×3 coupler, a fused triangular 3×3 single mode fiber coupler and three fiber arms in series,in which the planar 3×3 coupler is used as an input coupler, and the triangular 3×3 coupler as an output coupler. The output expression is derived and the numerical simulation is performed.The simulation indicates that the crosstalk characteristics and the coupling-coefficient-angle tolerance can be improved greatly, and the sidelobe level of channel of the proposed device has been reduced more than 13.6 dB as compared with that of the conventional all-fiber three-channel interleaver. A interleaver is fabricated with the fused biconical taper technics in an experiment. The experimental results are in good agreement with the analytical ones. The result shows that the measured sidelobe level and the insertion loss are less than -34.6 dB and 1.0 dB,respectively, and the channel isolation is higher than 30 dB.