多周期强激光场中高次谐波选择性增强

Control of Enhanced High-Order Harmonic Generation in a Multi-Cycle Laser Field

摘要: 本文利用强场近似理论模型，研究了多周期激光场中原子高次谐波的选择性增强。结果表明，利用多周期的800 nm、1600 nm及2400 nm的组合脉冲，谱段的谐波强度可以增强达一个数量级，并且调节脉冲间的延迟时间可以改变增强谐波的中心频率。通过时间频率分析，研究了该谐波增强的物理机制。

Abstract: By using strong-field approximation, we theoretically investigate the selective enhancement of high-order harmonic generation in a small spectral range driven by a multi-cycle three-color laser field which is composed of an 800 nm laser pulse, a 1600 nm laser pulse and a 2400 nm laser pulse. The results show that a narrow-bandwidth spectrum can be selectively enhanced with the intensity increased by nearly one order of magnitude compared to the adjacent harmonics, which can be attributed to the modified electron trajectories in the three-color field. Furthermore, it is revealed that the central wavelength of the enhanced spectrum can be effectively tuned by changing the time delay between laser pulses of different colors.