研制了一种基于掺Yb3+的双包层大模场面积偏振光子晶体光纤的耗散孤子锁模激光器.利用数值模拟分析了光纤激光器中耗散孤子动力学过程,与全正色散锁模激光器相比,脉冲窄化机理更加丰富,半导体可饱和吸收镜(SESAM)的非线性吸收,啁啾脉冲的光谱滤波以及光纤的增益色散同时起作用,这些因素使耗散孤子锁模更加容易实现,并且稳定运行.其中,光谱滤波的耗散过程是稳定锁模机制的主导因素,滤波片能够在频域和时域同时窄化脉冲,并且去除脉冲啁啾,限制脉冲在腔内始终小于1ps.在实验上实现了无色散补偿腔中直接输出脉冲宽度777fs,最高平均功率达到1W,重复频率48·27MHz,对应单脉冲能量20nJ的飞秒激光.
A dissipative-soliton mode locked laser based on Yb-doped single polarization large-mode-area photonic crystal fiber is demonstrated. The dissipative soliton dynamics is explored by numerical simulation. Compared with all normal dispersion fiber lasers, there are more pulse shaping mechanisms in a dissipative-soliton fiber laser, including the nonlinear absorption of SESAM, spectrum filtering of the chirped pulse and gain dispersion, which results in robust and stable operation. Among them, spectrum filtering plays a dominant role in mode-locking, it shapes pulse both in frequency domain and time domain and keeps the pulse duration below 1 ps in the cavity. For the first time, sub-1 ps pulse is directly generated in a dispersion compensation free cavity. The fiber laser directly generates 777 fs pulse at 1 W average power at a repetition rate of 51.4 MHz, corresponding to a single pulse energy of 20 nJ.