Ultrabroad Terahertz Spectrum Generation from an Air-Based Filament Plasma
Ultrabroad Terahertz Spectrum Generation from an Air-Based Filament Plasma
复制标题
气基灯丝等离子体产生的超宽太赫兹频谱
DOI：
10.1103/physrevlett.116.063902
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发表时间：
2016-02-11
影响因子：
8.6
通讯作者：
Chin, S. L.
中科院分区：
文献类型：
--
作者：
Andreeva, V. A.;Kosareva, O. G.;Chin, S. L.
解决了空气中双色灯丝产生太赫兹（THz）辐射的机制问题，发现中性粒子和等离子体都对辐射有贡献。我们发现，从中性的四波混频的贡献是更弱和更高的频率比独特的等离子体低频的贡献。前者是在向前的方向，而后者是在一个圆锥形，并揭示了一个突然向下移动的等离子体频率。太赫兹辐射的环形空间分布是普遍的性质，它们发生在准直和聚焦传播几何形状。实验测量的130-fs激光脉冲产生的频率-角谱同意基于单向脉冲传播模型的数值模拟。
We have solved the long-standing problem of the mechanism of terahertz (THz) generation by a two-color filament in air and found that both neutrals and plasma contribute to the radiation. We reveal that the contribution from neutrals by four-wave mixing is much weaker and higher in frequency than the distinctive plasma lower-frequency contribution. The former is in the forward direction while the latter is in a cone and reveals an abrupt down-shift to the plasma frequency. Ring-shaped spatial distributions of the THz radiation are shown to be of universal nature and they occur in both collimated and focusing propagation geometries. Experimental measurements of the frequency-angular spectrum generated by 130-fs laser pulses agree with numerical simulations based on a unidirectional pulse propagation model.