Nikolaeva I A, Shipilo D E, Pushkarev D V, Rizaev G E, Mokrousova D V, Koribut A V, Grudtsyn Y V, Panov N A, Seleznev L V, Liu W, Ionin A A, Kosareva O G
Opt Lett. 2021 Nov 1;46(21):5497-5500. doi: 10.1364/OL.439901.
In the experiment, the laser pulse (744 nm, 0.5 mJ, 90 fs) focused into the air gap between the plane electrodes biased by a 10 kV/cm field (DC-biased filament) produced terahertz (THz) radiation. At the selected frequencies of =0.3, 0.5, 1 THz, a wide flat-top angular distribution was measured by a bolometer rotating in the plane of the electrodes. The simulations based on the unidirectional pulse propagation equation with fine 0.01 THz resolution and 3 PHz frequency domain showed the transition of the THz directional diagram from the flat-top at ≲1 to the conical one at >8 due to the destructive interference of THz waves from the ionization front propagating with the superluminal velocity. Refraction on the plasma is not the major factor in ring formation.
在该实验中，将激光脉冲（744纳米，0.5毫焦，90飞秒）聚焦到由10千伏/厘米电场（直流偏置细丝）偏置的平面电极之间的气隙中，产生太赫兹（THz）辐射。在选定的频率 =0.3、0.5、1太赫兹下，通过在电极平面内旋转的测辐射热计测量到宽平顶角分布。基于具有0.01太赫兹精细分辨率和3拍赫兹频域的单向脉冲传播方程进行的模拟表明，由于以超光速传播的电离前沿产生的太赫兹波的相消干涉，太赫兹方向图从低于1时的平顶转变为高于8时的锥形。等离子体上的折射不是形成环形的主要因素。
