Physical processes near threshold in strong field ionization are complex owing to the important role of many intermediate states. Two typical near-threshold processes in few-cycle laser pulses, generations of Rydberg electrons and Terahertz wave, are investigated using the Classical Trajectory Monte Carlo simulations. Mapping final energies of electrons to the tunneling coordinates, the two processes are distinguished based on the contributions from different kinds of electron trajectories, which highlights the complex interplay between the Coulomb potential and laser field on the electron dynamics. We clarify the dependence of momentum and energy spectra on the carrier-envelope phase. We find that the optimal phases for Terahertz wave generation and creation of the Rydberg state in few-cycle laser pulses are opposite. This finding can be applied for the further experiments on attosecond electron dynamics.

中文翻译：

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里德堡状态的动态和在强几个周期的激光脉冲中产生的太赫兹波

由于许多中间状态的重要作用，在强场电离中接近阈值的物理过程很复杂。使用经典轨迹蒙特卡洛模拟研究了几个周期激光脉冲中的两个典型的近阈值过程，即里德伯格电子的产生和太赫兹波的产生。将电子的最终能量映射到隧穿坐标，可根据不同类型电子轨迹的贡献来区分这两个过程，这突出了库仑势和激光场在电子动力学上的复杂相互作用。我们阐明了动量和能谱对载流子-包络相的依赖性。我们发现，在几个周期的激光脉冲中，太赫兹波产生和里德堡态产生的最佳相位是相反的。