为克服基于普通单模光纤的声光效应只能实现带阻滤波器的问题 ,提出并实现了一种三段式结构的全光纤带通型可调谐声光滤波器。该文分析了三段式结构实现带通滤波的原理 ,考虑声波的衰减而优化了第一段和第三段光纤的长度比 ,并且指出中间段光纤的长度对于滤波器消光比的影响。这种新型结构的滤波器与以往的全光纤滤波器相比 ,边带抑制比高 ,没有移频现象 ,适合于高速波分复用系统的应用 In order to overcome the problem of band-stop filter based on the acousto-optic effect of ordinary single-mode fiber, a three-stage all-fiber band-pass tunable acousto-optic filter is proposed and implemented. This paper analyzes the principle of band-pass filtering in three-stage structure, and optimizes the length ratio of the first and the third fiber considering the attenuation of the acoustic wave. It also points out the influence of the length of the middle fiber on the extinction ratio of the filter. Compared with the conventional all-fiber filter, the novel structure of the filter has high sideband suppression ratio and no frequency shift, and is suitable for the application of a high-speed wavelength division multiplexing system