缓慢上升快速下降的飞秒激光脉冲与气体等离子体作用的太赫兹辐射产生研究

THz generation from slow turn-on,rapid turn-off femtosecond laser pulses interaction with gas plasma

飞秒激光脉冲与气体等离子体作用可以产生宽带、强的太赫兹脉冲辐射。采用一种缓慢上升、快速下降的飞秒激光脉冲与气体等离子体作用产生太赫兹辐射,并基于等离子体电流模型计算了这种太赫兹辐射的特性。由于这种特殊整形的激光脉冲能够对电子的加速产生较大的速度,从而可以产生较大的等离子体电流和较强的太赫兹辐射。计算结果显示:尽管这种特殊整形的飞秒激光脉冲能量有所损失,它能够比普通双色飞秒激光脉冲产生更强、更宽的太赫兹脉冲辐射。该项研究为基于激光等离子体作用的太赫兹辐射源提供了新的思路。

The interaction between the femtosecond laser pulses and the gas plasma has been widely used to generate strong and broadband THz pulse radiation.A femtosecond laser pulse with slow turn-on,rapid turn-off shape was used to generate THz radiation by interacting with gas plasma.Based on the plasma current model,the properties of the THz generation from such scheme were investigated in detail.Because the electrons were accelerated to a fast velocity by such specially shaped laser pulses,their motions form a fast oscillation current,which emits electromagnetic wave with frequency in the THz region.The results show that such scheme can generate stronger and broader THz radiation than the normal two-color femtosecond laser scheme,although it loses some energy of the laser pulse.This proposal might offer a new way to develop plasma-based broadband THz radiation source.