实验采用共振增强式非线性折射率调制技术实现了半导体可饱和吸收镜锁模全保偏掺镱光纤激光器重复频率的精确锁定。在掺镱光纤激光器的腔内加入一个980/1064 nm的波分复用器(WDM)和一段掺铒增益光纤，通过反馈控制加载在该掺铒光纤上的976 nm抽运光LD2功率调控掺铒光纤的非线性折射率，进而对激光器的光学腔长实施控制，最终实现重复频率的精确锁定。优化了不同掺铒光纤长度及抽运光初始功率对激光器重复频率控制范围和锁定精度的影响。结果表明：当掺铒光纤长度为1.75 m时，通过调整抽运光功率能够实现180 Hz的重复频率调整范围；而重复频率的锁定精度仅与抽运光的初始功率密切相关，并不受掺铒光纤长度的明显影响。当LD2抽运光强度为18 mW时，重复频率峰-峰值的波动范围小于0.5 mHz,相应的标准偏差为0.16 mHz，输出功率的标准偏差为0.009 mW。此外，通过反馈控制抽运源LD1的强度，并取掉了腔内的掺铒增益光纤及与其相连的WDM，发现由于共振增强非线性和克尔非线性对光纤折射率的叠加，在稳定的单脉冲锁模区间内，重复频率单调变化的范围增加至1 kHz，而锁定精度略有降低。

High precision locking of the repetition rate of a semiconductor saturable absorber mirror mode-locked all polarization maintaining fiber laser is achieved by using the method of resonance-enhanced nonlinearity in an additional active fiber. A 980/1064 nm wavelength division multiplexer (WDM) and a piece of Er-fiber are added in the fiber cavity to induce the change of nonlinear refractive index and optical cavity length. By feedback controlling the pump power of LD2, the refractive index of the Er-fiber is modulated, and thus the optical length of the laser can be controlled to achieve the high precision locking of the repetition rate. The length of the Er-fiber and the initial pump power of LD2 are optimized to maximize the range and precision for repetition rate locking. Results show that as much as 180 Hz controlling range is obtained in the condition of 1.75 m length of Er-fiber. The repetition rate of locking accuracy is just closely related to the initial pump power and is not significantly affected by the length of Er-fiber. The range of repetition rate peak-to-peak is less than 0.5 mHz, the corresponding standard deviation is 0.16 mHz, and the standard deviation of output power is 0.009 mW in the condition of 18 mW pump power of LD2. Moreover, the pump power of LD1 is controlled by the feedback, when removing Er-fiber and the WDM. Due to the superposition of the resonance-enhanced nonlinearity and the Kerr nonlinearity on the refractive index of Yb-fiber, the repetition rate increases to 1 kHz with a slightly decrease of locking accuracy in a stable single pulse mode locking range.