为消除体相位调制器工作过程中热效应对偏振调制测距精度的影响，提出了利用波导式相位调制器替代体相位调制器的全光纤波导式偏振调制测距方法。对波导式偏振调制测距系统进行原理分析，利用琼斯矩阵得出传输过程中测量光偏振态的变化规律，建立调制信号频率、偏振光强度与被测距离的函数关系。然后，进行了直波导相位调制器特性测试，验证其半波电压随调制频率在3.5~7 V之间变化，正反电光响应一致性为-2%~3%。最后，构建波导式偏振调制测距系统装置并进行实验验证，重复性测试实验中测量平均误差为0.44 mm，测量重复性为0.54 mm，变距离实验中测量平均误差为0.39 mm。波导式偏振调制测距系统能够实现距离的有效测量，具有不产生热效应，结构简单等优点，在激光测距方面具有应用价值。

In this Letter, we report on a novel architecture for a self-starting mode-locked figure-eight erbium-doped fiber laser using a loss-imbalanced nonlinear optical loop mirror (NOLM) with a bidirectional output coupler. An all-polarization-maintaining structure is adopted. A 2 × 2 optical coupler with a splitting ratio of 50:50 is used at the junction to form an NOLM. Another coupler with a splitting ratio of 10:90 is introduced at one end of the fiber loop. The 10:90 coupler plays two roles: power attenuator and bidirectional output coupler. This architecture can achieve both large modulation depth and good self-starting ability simultaneously. With this architecture, the self-starting mode-locking operation is achieved easily with pump power above the threshold. The clockwise and counter-clockwise mode-locked output powers are 10.1 and 10.3 mW, respectively, with the repetition rate of 3.63 MHz. The spectral bandwidths of the clockwise and counter-clockwise mode-locked output pulses are 7.4 and 2.9 nm, and the corresponding pulse widths of the direct outputs are 530.6 fs and 1.55 ps, respectively.