全正色散高阶谐波锁模掺Yb光纤激光器

High-Order Harmonic Mode-Locked Yb-Doped Fiber Laser with All Normal Dispersion

在全正色散（ANDi）系统中,报道了最高为21阶的被动谐波锁模（HML）掺Yb光纤激光器。利用级联长周期光纤光栅（C-LPFG）作为全光纤结构的光谱滤波器,以非线性偏振演化（NPE）效应作为锁模机理,得到了重复频率可调谐的被动谐波锁模掺Yb激光输出,实现输出脉冲重复频率1.544～32.42MHz的可调谐。并进一步论证了谐波阶次的提高不仅与抽运功率有关,而且与光纤的长度有关。

A high-order harmonic and passively mode-locked Yb-doped with all-normal dispersion fiber laser is reported and demonstrated. With the mode-locking mechanism of nonlinear polarization evolution （NPE） effect and a cascade long period fiber grating （C-LPFG） as an all-fiber format spectral filter for the strong pulse shaping, a maximum of 21th-order harmonic mode-locked （HML） Yb-doped fiber laser can be tunably achieved with the repetition rate from 1. 544 MHz to 32.42 MHz. It is further confirmed that the order of the HML is dependent on the cavity length and the pump power.