由于群速度的偏振依赖性,飞秒激光脉冲入射到双波长波片时出射光脉冲会分离为两个具有一定时间延迟的飞秒激光脉冲。从实验和理论模拟两方面研究了双波长波片导致的脉冲分离现象对飞秒激光双色场成丝辐射太赫兹(THz)波效率的影响。实验结果表明,脉冲分离导致的时间延迟会降低双色场辐射THz波的效率,可通过零级双波长波片缩短分离脉冲之间的时间延迟,有效提高THz波的产生效率。

We theoretically propose a new method for generating intense isolated attosecond pulses during high-order harmonic generation (HHG) process by accurately controlling electron motion with a two-color laser field, which consists of an 800-nm, 4-fs elliptically polarized laser field and a 1400-nm, ~43-fs linearly polarized laser field. With this method, the supercontinua with a spectral width above 200 eV are obtained, which can support a ~15-as isolated pulse after phase compensation. Classical an