为了使光纤激光器同时运转在不同的工作状态, 搭建了非线性偏振旋转(NPR)技术和碳纳米管可饱和吸收体(CNT-SA)混合的掺铒光纤激光器。其中, 基于NPR效应的腔内双折射引入的梳状滤波器可以实现双波长输出, NPR和CNT-SA的可饱和吸收效应共同作用可以获得调Q或调Q锁模脉冲, 因此在该激光器中通过调节参数可以使光纤激光器同时获得双波长调Q和调Q锁模脉冲输出。该双波长脉冲经滤波处理后, 观察到1531.23 nm处的波长对应调Q脉冲, 其重复率为45.62 kHz, 1557.18 nm处的波长对应调Q锁模, 调Q包络重复率也为45.62 kHz, 包络内锁模脉冲的重复率为18.18 MHz, 与激光器腔长相符。该实验结果增强了光纤激光器工作的灵活性, 有望进一步拓展其在相关领域的应用。

In order to make the fiber laser operate in two different states simultaneously, the erbium-doped fiber laser with both nonlinear polarization rotation (NPR) technique and carbon nanotube saturable absorber (CNT-SA) was fabricated in this experiment. The intra-cavity birefringence-induced comb filter based on NPR effect was employed to realize the dual-wavelength operation, and the Q-switched and Q-switched mode-locking pulses could be achieved by utilizing the NPR technique and the CNT-SA together. Therefore, the coexistence of Q-switched and Q-switched mode-locking pulses could be obtained in the fiber laser by finely adjusting the cavity parameters. After filtering each wavelength, it was found that the lasing line at 1531.23 nm corresponded to the Q-switched pulse with repetition rate of 45.62 kHz, while the lasing line at 1557.18 nm corresponded to the Q-switched mode locking pulse. The Q-switched envelope repetition rate and pulse repetition rate of the Q-switched mode locking pulses are 45.62 kHz and 18.18 MHz, respectively. The experimental results would enhance the operation flexibility of fiber laser, and further expand its application in related fields.