Measurement of Terahertz radiation from plasma antenna

等离子体天线是用超短激光脉冲照射气体中的高压电极形成的。等离子体中的电流及其上升时间与激光脉冲具有相同的时间尺度。发射的辐射频率估计在太赫兹区数量级。在实验中，我们在真空容器中使用氮气，当激光脉冲宽度为120 fsec时，我们在频率上观察到0.08太赫兹的辐射脉冲，而使用30 fs的激光脉冲时，我们观察到0.3太赫兹的辐射频率。辐射频率取决于理论模型所期望的激光脉冲宽度。

The plasma antenna forms by the ultra short laser pulse irradiation to the high-voltage applied electrodes in the gas. The current flows in the plasma and its rise time is expected to be same time scale of laserpulse. The emitted radiation frequency is estimated in the order of THz regime.In the experiments, we used nitrogen gas in the vacuum vessel, when laser pulse width is 120 fsec, we observed 0.08 THz radiation pulse in the frequency, moreover 0.3 THz radiation frequency was observed by using 30 fs laser pulse. The radiation frequency depends on the laser pulse width as expected by the theoretical model.