We report the ionization reduction of atoms in two-color femtosecond laser fields in this joint theoretical-experimental study. For the multiphoton ionization of atoms using a 400 nm laser pulse, the ionization probability is reduced if another relatively weak 800 nm laser pulse is overlapped. Such ionization reduction consistently occurs regardless of the relative phase between the two pulses. The time-dependent Schrödinger equation simulation results indicate that with the assisted 800 nm photons the electron can be launched to Rydberg states with large angular quantum numbers, which stand off the nuclei and thus are hard to be freed in the multiphoton regime. This mechanism works for hydrogen, helium, and probably some other atoms if two-color laser fields are properly tuned.

中文翻译：

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双色飞秒激光场中原子的多光子电离还原

在这项联合理论-实验研究中，我们报告了双色飞秒激光场中原子的电离还原。对于使用 400 nm 激光脉冲的原子多光子电离，如果重叠另一个相对较弱的 800 nm 激光脉冲，则电离概率会降低。无论两个脉冲之间的相对相位如何，这种电离减少都会持续发生。随时间变化的薛定谔方程模拟结果表明，在 800 nm 光子的辅助下，电子可以发射到具有大角量子数的里德伯态，这些态远离原子核，因此在多光子状态下很难被释放。如果正确调整双色激光场，这种机制适用于氢、氦和可能的其他一些原子。