超低阈值Q调制，锁模Yb3+光纤环形腔激光器

 在一种掺镱（Yb³⁺）光纤锁模激光器中。谐振腔采用近“8”字形环形结构，并巧妙地引入半导体可饱和吸收镜（SESAM），腔内引入起偏器和偏振控制器，利用非线性偏振旋转的被动锁模机理，结合SESAM慢可饱和吸收体的自启动作用，在极低的泵浦功率下，实现了稳定的调Q脉冲输出和锁模输出。当泵浦功率为18 mW时，调Q脉冲重复频率为16 kHz，脉冲宽度4 μs，光谱宽度为2.34 nm。当泵浦功率为60 mW时，实现了激光器连续锁模，输出功率8 mW，重复频率20 MHz，光谱宽度3.54 nm，脉宽在ps和亚ps量级，而且在调整偏振控制器的角度时，观察到了波长的调谐现象，调谐范围为1 028~1 530 nm。

Mode-locked and Q-modulation switched Yb3+ doped ring cavity fiber laser with low pump power

The experimental study of a passive mode locked Yb3+ doped fiber laser was reported, which utilized a 8 shaped ring cavity with semiconductor saturable absorber mirror(SESAM) as well as the polarizer and polarization controllers. Combining the effect of non-linear polarization rotation with the self starting of SESAM, stable operations of Q switched and CW mode locked regime at the low pump power were achieved. When the pump power was 18 mW, the Q switched pulse with a repetition of 16 kHz, a pulse width of 4 μs ,and an output spectrum width of 2.34 nm was obtained. When the pump power was 60 mW, the output power of mode locked pulses was 8 mW, the repetition was 20 MHz, the output spectrum width was 3.54 nm, and the pulse width was ps or sub ps orders. The tunable phenomenon with proper