非线性放大环形镜被动锁模光纤激光器重复频率精确锁定研究

Repetition Rate Precision Lock of Nonlinear Amplifying Loop Mirror Passively Mode-Locked Fiber Laser

采用共振增强式非线性折射率调制技术实现了非线性放大环形镜锁模掺镱全保偏光纤激光器重复频率的精确锁定。通过在激光器非线性环内加入一个能提供线性相移的非互易性元件,有效减小了锁模脉冲的抽运阈值。进一步优化激光器的锁模抽运功率和控制光纤非线性折射率的抽运功率,可使激光器直接输出的最短脉冲为590fs,重复频率为20.48 MHz,重复频率峰-峰值的波动范围小于0.4mHz,相应的标准偏差为0.1mHz。

High precision repetition rate stabilization is realized in an all polarization-maintaining nonlinear amplifying loop mirror（NALM）mode-locked Yb-fiber laser.An additional Er-fiber is added in the nonlinear loop to control the optical length by the resonance-enhanced nonlinearity modulation technique.Moreover,an integrated nonreciprocal device with linear phase shift effectively reduces the mode-locking threshold.By optimizing both the pump power from two laser diodes for mode locking and the nonlinear refractive index modulating,we can obtain the shortest pulse of 590 fs and repetition rate of 20.48 MHz,the peak-to-peak fluctuation of repetition rate is less than 0.4 mHz,and the corresponding standard deviation is 0.1 mHz.