中文摘要：

研究了电子在聚焦的圆偏振高斯激光束中的非线性汤姆孙散射过程,在此基础上提出了实现单个阿秒脉冲输出的新机理.通过计算机模拟,发现利用紧聚焦的激光脉冲可以有效地增大辐射脉冲链的最高峰和次高峰的峰值强度比即信噪比,从而将阿秒脉冲链变为单个阿秒脉冲输出.紧聚焦情形下,随着驱动激光强度的增大,辐射信号的脉宽变短,信噪比变大;同时当减小激光束腰半径时,辐射信号信噪比也能得到有效改善.研究还发现,利用几个光周期的极短激光脉冲与电子的相互作用也能实现单个阿秒脉冲输出.

英文摘要：

The nonlinear Thomson scattering by an electron in a focused circularly polarized laser beam is investigated and a novel scheme for single attosecond pulse generation is proposed. Through computer simulation we find that by using a tightly focused laser beam, the ratio of the highest peak pulse and the second highest peak pulse of the radiation which is defined as the signal- to-noise ratio can be efficiently increased, such that a single attosencond pulse rather than a train of attosecond pulses is obtained. The pulse duration of the radiation decreases and the signal-to-noise ratio increases with increasing laser intensity. Simultaneously, the signal-to-noise ratio can be also improved as the beam-waist decreases. We find that a single attosencond pulse can be generated by using a few-cycle ultrashort laser pulse as well.