Terahertz (THz) radiation from an inhomogeneous plasma filament generated by focusing two-color femtosecond laser pulses into argon gas filled in a chamber is investigated experimentally by tailoring the Gaussian pump laser beams with an iris, where broadband THz emission over 10 THz is produced. It is found that the collected far-field THz radiation includes not only coherent but also partial-coherent components of the THz waves, which are emitted from the different parts of the inhomogeneous plasma filament with different plasma densities, contributing correspondingly to the different frequencies of the THz spectrum. Our results suggest that the THz spectrum can be manipulated by controlling the plasma density distribution of the filaments.

中文翻译：

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通过定制两种颜色的激光束来控制不均匀等离子灯丝的太赫兹辐射的光谱

通过定制具有虹膜的高斯泵浦激光束，对通过将两种颜色的飞秒激光脉冲聚焦到填充在室内的氩气中而产生的不均匀等离子灯丝产生的太赫兹（THz）辐射进行了研究，产生了超过10 THz的宽带THz发射。发现所收集的远场太赫兹辐射不仅包括太赫兹波的相干分量，而且还包括部分相干分量，这些分量是从具有不同等离子体密度的不均匀等离子灯丝的不同部分发出的，分别对应于太赫兹频谱。我们的结果表明，可以通过控制细丝的等离子体密度分布来控制THz光谱。