针对三通道波分复用技术，本文提出了一种利用三个3×3 光纤耦合器级联组成的全光纤Mach-Zehnder 干涉仪型三波分复用器，运用光纤传输理论和矩阵理论，得到光谱的输出表达式。通过数值模拟分析了各3×3 耦合器耦合比和光纤臂长差对该三波分复用器的影响，并进行了实验。结果表明，当组成的全光纤Mach-Zehnder 干涉仪型三波分复用器的三条光纤干涉臂两两之间分别存在长度差ΔL 和2ΔL 时，在耦合器分光比取一些定值时即可实现三波分复用功能，三端口输出谱线理想，波长间隔仅仅取决于ΔL 的大小，且该器件的输出谱线对耦合器的耦合比不太敏感。实验样品采用的波段为1.55 μm，波长复用间隔为0.8 nm，实验所得的结果与理论相吻合。

According to three-wavelength-division-multiplexer, a three-port all-fiber optical Wavelength-divisionmultiplexer was developed by using a new configuration of cascading three 3×3 directional fiber couplers, which was made of three 3×3 single-mode fiber couplers connected by 3 single-mode fibers. Based on the principle of characteristics of fiber transmissivity, the complex amplitude output spectral expression was established and described by using the matrix transfer function. Through numerical simulation and experiment, the influence of the coupling coefficient of the couplers and the lengths of these 3 single-mode fiber on the three-wavelength-division-multiplexer was analyzed. The analytical results indicate that when the lengths of these 3 single-mode fiber are L, L+ΔL, and L+ 2ΔL, respectively and the coupling coefficient of the couplers is some certain values, three-wavelength-division-multiplexer acts as a 3 channel wavelength-division-multiplexer and the port output curves are quite ideal. The experimental sample is tested at 1.55 μm working wavelength and the peak output power interval of 0.8 nm. The experiment results are in good agreement with the analytical ones.