Development of high power THz source using phase control technique

我们已经证明，在脉冲电场作用下，激光产生的电离波阵面在空气中产生光场感应电离(OFI)，产生的猝发电流可以产生相控太赫兹辐射。辐射谱的峰值频率取决于OFI的上升时间。在脉冲宽度分别为30和100飞秒(FWHM)时，观察到辐射的中心频率分别为0.3和0.1太赫兹。我们还利用太赫兹波与超短激光脉冲产生的等离子体之间的相互作用，演示了闪光电离方案的原理验证实验。当在电磁波周围瞬间产生等离子体时，电磁波的频率上转换为取决于等离子体频率的频率。利用激光在锌硒晶体中的辐照度，我们观察到了0.35太赫兹到3太赫兹的频率上转换。

We have demonstrated that the phase-controlled terahertz radiation can be generate by the burst current produced by a laser created ionization front, which is induced an optical-field-induced ionization (OFI) in air with a pulsed electric field. The peak frequency of the radiation spectrum depends on the rise time of the OFI. The central frequencies of the radiation were observed to be 0.3 and 0.1 THz at the pulse durations of 30 and 100 fs (FWHM), respectively. We also have demonstrated the proof-of-principle experiment of flash ionization scheme using the interaction between a terahertz wave and plasmas created by an ultrashort laser pulse. When plasmas were instantaneously created around an electromagnetic wave, frequency of the wave up-converted to the frequency, which depended on the plasma frequency. We observed frequency up-conversion from 0.35 THz to 3 THz by the irradiance of the laser in ZnSe crystal.