Cavity-birefringence-dependent h-shaped pulse generation in a thulium-holmium-doped fiber laser.
Cavity-birefringence-dependent h-shaped pulse generation in a thulium-holmium-doped fiber laser.
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DOI：
10.1364/ol.43.000247
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发表时间：
2018-01
期刊：
影响因子：
3.6
通讯作者：
Junqing Zhao;Lei Li;Luming Zhao;D. Tang;D. Shen
中科院分区：
文献类型：
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作者：
Junqing Zhao;Lei Li;Luming Zhao;D. Tang;D. Shen
报道了一种在掺Tm-Ho光纤激光器中产生的2μmh形脉冲，并对其腔双折射和泵浦功率进行了实验研究。采用非对称非线性光学环镜作为人工可饱和吸收体，采用∼52.7m色散位移光纤和∼3.8m超大数值孔径光纤来增强非线性。即使采用随机弱双折射光纤，H型脉冲也表现出与偏振态(PS)和泵浦功率相关的演化。通过进一步加入不同长度的高双折射保偏光纤(PMF)，即引入不同量的线腔双折射，可以实现更大的脉冲调谐范围。特别是，当通过操纵PS将偏振模色散延长到∼2.3m时，获得的最长脉冲宽度为∼318.14 ns，几乎可以覆盖∼323.96 ns的整个重复周期，相当于∼98.2%的脉冲占空比，这是我们所知的光纤激光器中最大的。我们详细地展示了相关的特征。
We report on a type of 2 μm h-shaped pulse generation in a thulium-holmium-doped fiber laser and experimentally investigate its cavity birefringence and pump power dependences. An asymmetric nonlinear optical loop mirror is employed as an artificial saturable absorber, which incorporates ∼52.7 m dispersion-shifted fiber and ∼3.8 m ultra-high numerical aperture fiber to enhance the nonlinearity. The h-shaped pulse shows both a polarization state (PS) and pump power related evolutions, even when randomly weak birefringence fibers are employed. By further incorporating different lengths of high birefringence polarization-maintaining fiber (PMF), i.e., introducing different amounts of linear cavity birefringence, much larger pulse tuning ranges can be realized. In particular, when the PMF is lengthened to ∼2.3 m through manipulating the PS, the achieved longest pulse duration of ∼318.14 ns can almost cover the whole repetition period of ∼323.96 ns, corresponding to a pulse duty circle of ∼98.2%, the largest ever reported from a fiber laser, to the best of our knowledge. We demonstrate the related characteristics in detail.