提出并分析验证了一种利用有源环形滤波器对有理数谐波锁模激光器输出光脉冲幅度进行均衡的方案。方案中，光纤结构的有源环形滤波器被视为一个自由光谱范围可调谐的梳状滤波器，使有理数谐波锁模激光器输出光脉冲中的锁模分量通过而其他谐波分量和超模得到抑制，获得幅度均衡的光脉冲。理论上，对经过有源环形滤波器前后光脉冲的波形和频谱分别进行了仿真，结果表明有源环形滤波器能有效滤出所需的锁模频率，且Q 值越高，光脉冲的幅度均衡效果越佳。在7阶、11阶、14阶有理数谐波锁模条件下通过实验进行验证，均获得了良好的效果，模式抑制比可提高20 dB以上。

A scheme of equalizing the uneven pulse amplitude from a rational harmonic mode-locked laser is proposed and verified, in which an optical fiber active ring filter is employed. The active ring filter is a comb filter with tunable free spectral range, which can select the mode-locked component and suppress other harmonics and super-modes by carefully tuning the optical delay line in it. This process is able to effectively balance the pulse amplitude. Theoretically, the simulation is performed to compare the waveform and radio frequency spectrum before and after filtering. The results show that the active ring filter can effectively filter the expected frequency, and the higher the Q is, the better the amplitude equalizationisis. In the experiment, the 7th, 11th, 14th mode-locked pulses are verified respectively and mode-suppression ratio can be improved by more than 20 dB.