Enhancement of high harmonics generated by field steering of electrons in a two-color orthogonally polarized laser field.
Enhancement of high harmonics generated by field steering of electrons in a two-color orthogonally polarized laser field.
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DOI：
10.1364/ol.35.003994
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发表时间：
2010-12
期刊：
影响因子：
3.6
通讯作者：
L. Brugnera;F. Frank;D. Hoffmann;R. Torres;T. Siegel;J. Underwood;E. Springate;C. Froud;E. Tu
中科院分区：
文献类型：
--
作者：
L. Brugnera;F. Frank;D. Hoffmann;R. Torres;T. Siegel;J. Underwood;E. Springate;C. Froud;E. Tu
通过将1300 nm(10(14)W cm(-2))的基场与650 nm(2×10(13)W cm(-2))的正交极化二次谐波相结合，并控制它们之间的相对相位，我们证明了Ar产生的高次谐波有1个数量级的增强。与以前的800/400 nm场方案相比，这扩展了早期的工作，确保主要效应是引导电子轨迹的组合场，而多光子效应的贡献可以忽略不计。在较低的激光强度(远低于电离饱和极限)下，我们获得了较宽的谐波能量范围(从20 eV到80 eV)，并观察到相对位相周期为π的谐波产额的深度调制。强场理论分析表明，这主要是由于双色场对再碰撞电子波包的引导。我们的模型还表明，atto的啁啾是可以控制的，从而产生更短的脉冲。
We demonstrate enhancement by 1 order of magnitude of the high-order harmonics generated in argon by combining a fundamental field at 1300 nm (10(14) W cm(-2)) and its orthogonally polarized second harmonic at 650 nm (2 × 10(13) W cm(-2)) and by controlling the relative phase between them. This extends earlier work by ensuring that the main effect is the combined field steering the electron trajectory with negligible contribution from multiphoton effects compared to the previous schemes with 800/400 nm fields. We access a broad energy range of harmonics (from 20 eV to 80 eV) at a low laser intensity (far below the ionization saturation limit) and observe deep modulation of the harmonic yield with a period of π in the relative phase. Strong field theoretical analysis reveals that this is principally due to the steering of the recolliding electron wave packet by the two-color field. Our modeling also shows that the atto chirp can be controlled, leading to production of shorter pulses.