Nonlinear polarization dynamics in a weakly birefringent all-normal dispersion photonic crystal fiber: toward a practical coherent fiber supercontinuum laser.
Nonlinear polarization dynamics in a weakly birefringent all-normal dispersion photonic crystal fiber: toward a practical coherent fiber supercontinuum laser.
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DOI：
10.1364/oe.20.001113
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发表时间：
2012-01-16
期刊：
影响因子：
3.8
通讯作者：
Boppart SA
中科院分区：
文献类型：
--
作者：
Tu H;Liu Y;Liu X;Turchinovich D;Lægsgaard J;Boppart SA
色散-平坦色散-减小全正常色散（DFDD-ANDi）光子晶体光纤被认为是高光谱功率相干超连续谱（SC）产生的有前途的候选者。然而，光纤的非故意双折射对SC产生的影响被忽略了。这种双折射现象广泛存在于典型纤芯尺寸为2 μ m的非线性非偏振维持光纤中，可能是由于光纤拉伸过程中引入的结构对称性破坏。我们发现，在DFDD-ANDi光子晶体光纤中，10−5量级的本征形式双折射深刻地影响SC的产生。基于标量广义非线性Schrödinger方程（GNLSE）的传统模拟无法再现在短段（9厘米）光纤中SC产生的突出特征。然而，考虑到形式双折射的耦合GNLSE可以定性或半定量地理解这些特征。双折射引起的非线性极化效应显著地扭曲了SC脉冲的光谱时间场。因此，我们建议制造保偏DFDD-ANDi光纤，以避免在追求实用的相干光纤SC激光器中这些不利影响。
Dispersion-flattened dispersion-decreased all-normal dispersion (DFDD-ANDi) photonic crystal fibers have been identified as promising candidates for high-spectral-power coherent supercontinuum (SC) generation. However, the effects of the unintentional birefringence of the fibers on the SC generation have been ignored. This birefringence is widely present in nonlinear non-polarization maintaining fibers with a typical core size of 2 µm, presumably due to the structural symmetry breaks introduced in the fiber drawing process. We find that an intrinsic form-birefringence on the order of 10−5 profoundly affects the SC generation in a DFDD-ANDi photonic crystal fiber. Conventional simulations based on the scalar generalized nonlinear Schrödinger equation (GNLSE) fail to reproduce the prominent observed features of the SC generation in a short piece (9-cm) of this fiber. However, these features can be qualitatively or semi-quantitatively understood by the coupled GNLSE that takes into account the form-birefringence. The nonlinear polarization effects induced by the birefringence significantly distort the otherwise simple spectrotemporal field of the SC pulses. We therefore propose the fabrication of polarization-maintaining DFDD-ANDi fibers to avoid these adverse effects in pursuing a practical coherent fiber SC laser.