双色激光激励对空气中太赫兹辐射增强的研究

THz emission enhancement in air by two-color laser excitation

利用光电流模型模拟研究在泵浦光中引入400nm倍频光对空气中太赫兹辐射的增强情况,其中空气中氮气离化过程考虑到二阶离化,同时考虑电子在运动过程中与周围离子、分子的碰撞。结果表明,400nm激光的引入打破了原激光电场的对称性,导致了光电流中漂移成分的产生,大大增强了最后的太赫兹波输出强度。

Photocurrent model was used to study THz emission enhancement when air was irradiated by two-color laser pulses with introducing another 400 nm laser pulse. The second order ionization of nitrogen and the collision between the electrons and the surrounding ions and molecules were taken in- to account. The results show that the symmetry of laser field is broken by the introduction of the sec- ond harmonic 400 nm laser, which leads to the production of non-zero DC electron current and greater intensity of THz emission in the far field.