Attosecond phase locking of harmonics emitted from laser-produced plasmas
Attosecond phase locking of harmonics emitted from laser-produced plasmas
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DOI：
10.1038/nphys1155
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发表时间：
2009-02-01
期刊：
影响因子：
19.6
通讯作者：
Tsakiris, G. D.
中科院分区：
文献类型：
--
作者：
Nomura, Y.;Hoerlein, R.;Tsakiris, G. D.
激光驱动的相干极端紫外线(XUV)源提供持续数百阿秒(1，2)的脉冲，使人们能够实时获取物质(3，4)电子结构的动态变化，这是原子核外最快的过程。然而，这些脉冲通常相当弱。利用基于加速器的XUV光源的超高亮度(5)和基于激光的对应光源的独特的时间结构将在超快X射线和高场科学中开启诱人的机会，将强大的非线性光学和泵浦探测技术扩展到X射线频率，并为实现不同的辐射强度铺平道路。相对论激光-等离子体相互作用已被确定为实现这一目标的一种有希望的方法(6-13)。最近的实验证实，相对论驱动的超稠密等离子体能够以无与伦比的效率将红外激光转换为谐波XUV辐射，并证明了产生技术对硬X射线的可扩展性(14-19)。在这里，我们证明了从相互作用过程中发出的XUV谐波的相位是同步的，从而实现了阿秒时间聚束。结合之前关于能量转换的发现和高功率激光技术的最新进展，我们的实验证明了将前所未有的光能量限制在不到一飞秒的可能性。
Laser-driven coherent extreme-ultraviolet (XUV) sources provide pulses lasting a few hundred attoseconds(1,2), enabling real-time access to dynamic changes of the electronic structure of matter(3,4), the fastest processes outside the atomic nucleus. These pulses, however, are typically rather weak. Exploiting the ultrahigh brilliance of accelerator-based XUV sources(5) and the unique time structure of their laser-based counterparts would open intriguing opportunities in ultrafast X-ray and high-field science, extending powerful nonlinear optical and pump-probe techniques towards X-ray frequencies, and paving the way towards unequalled radiation intensities. Relativistic laser-plasma interactions have been identified as a promising approach to achieve this goal(6-13). Recent experiments confirmed that relativistically driven overdense plasmas are able to convert infrared laser light into harmonic XUV radiation with unparalleled efficiency, and demonstrated the scalability of the generation technique towards hard X-rays(14-19). Here we show that the phases of the XUV harmonics emanating from the interaction processes are synchronized, and therefore enable attosecond temporal bunching. Along with the previous findings concerning energy conversion and recent advances in high-power laser technology, our experiment demonstrates the feasibility of confining unprecedented amounts of light energy to within less than one femtosecond.