Measurement of Terahertz radiation from plasma antenna

利用超短激光脉冲照射气体中的高压电极，形成等离子体天线。等离子体中流动的电流的上升时间与激光脉冲的时间尺度相同。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 fs时，我们观测到了0.08 THz的辐射脉冲，而当激光脉冲宽度为30 fs时，我们观测到了0.3 THz的辐射频率。正如理论模型所预期的那样，辐射频率取决于激光脉冲宽度。

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.