双孤子被动锁模光纤激光器的实验研究

Experimental study on dual-soliton operation of a passive mode-locked fiber laser

利用非线性偏振旋转(NPR)效应,对被动锁模掺Er光纤激光器同时输出双波带、双孤子的现象进行了实验研究和理论分析。结果发现,激光腔内存在高的线性双折射是得到双波带、双孤子输出的关键条件,提供宽的增益带宽和较大的增益有利于得到稳定的锁模输出。通过在腔内引入较大的线性双折射,在基于NPR锁模技术的被动锁模掺Er光纤激光器中得到了重复频率为7.49 MHz、中心波长分别在1 542 nm和1 557 nm附近的双波带、双孤子锁模脉冲的同时输出。

A dual-wavelength and dual-soliton operation in a passive mode-locked Er-doped fiber laser is demonstrated by using nonlinear polarization rotation（NPR） technique and the formation mechanisms of this phenomenon are experimentally investigated.It is found that a high linear birefringence in the laser cavity is the key to obtain the dual-wavelength and dual-soliton mode-locked output.In order to get stable output,a broad gain bandwidth and a high gain are preferred.By introducing high linear birefringence in the laser cavity,a passive mode-locked Er-doped fiber laser is achieved with dual-wavelength mode-locked operation and dual-soliton output,with a repetition rate of 7.49 MHz and center wavelengths at 1 542 nm and 1 557 nm,respectively.Several mode-locked states of the laser are also experimentally investigated and discussed.