Extreme ultraviolet high-harmonic spectroscopy of solids
Extreme ultraviolet high-harmonic spectroscopy of solids
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DOI：
10.1038/nature14456
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发表时间：
2015-05-28
期刊：
影响因子：
64.8
通讯作者：
Goulielmakis, E.
中科院分区：
文献类型：
--
作者：
Luu, T. T.;Garg, M.;Goulielmakis, E.
激光驱动的原子、分子或等离子体产生的极紫外线(EUV)高次谐波辐射(1，2)是强大的阿秒光谱技术(3-5)的基础，并提供了对物质的基本结构和动力学性质的洞察(6，7)。这些光谱技术在研究凝聚态中的强场电子动力学方面的进步要求在块状固体中产生和操纵EUV辐射，但这种能力仍然超出了光学科学的范围。最近的实验(8，9)和理论预测(10-12)为固体中的强场物理铺平了道路，它们展示了块状半导体中深紫外线辐射的产生和光学控制(8)，这种辐射是由飞秒中红外场或太赫兹场在中红外和光学频率(9)中的相干上转换为多倍频程光谱所驱动的。在这里，我们证明了二氧化硅薄膜暴露在强烈的，几个周期到亚周期的脉冲下，可以产生能量扩展到大约40电子伏特的宽带相干EUV辐射。我们的研究表明，发射的EUV辐射与在SiO_2最低导带感应的多拍赫兹频率的带内电流之间存在关联。为了证明高次谐波光谱对固体的适用性，我们利用EUV光谱来获得导带能量色散分布的精细细节，这些细节目前还无法通过宽禁带介质中的光电子能谱来获得。此外，我们还利用EUV光谱跟踪了由合成的光学瞬变引起的带内电子运动的阿秒控制。我们的工作将凝聚态物质中的光波电子学(5，13-15)推进到多拍赫兹频率及其阿秒控制的领域，标志着固态EUV光子学的到来。
Extreme ultraviolet (EUV) high-harmonic radiation(1,2) emerging from laser-driven atoms, molecules or plasmas underlies powerful attosecond spectroscopy techniques(3-5) and provides insight into fundamental structural and dynamic properties of matter(6,7). The advancement of these spectroscopy techniques to study strong-field electron dynamics in condensed matter calls for the generation and manipulation of EUV radiation in bulk solids, but this capability has remained beyond the reach of optical sciences. Recent experiments(8,9) and theoretical predictions(10-12) paved the way to strong-field physics in solids by demonstrating the generation and optical control of deep ultraviolet radiation(8) in bulk semiconductors, driven by femtosecond mid-infrared fields or the coherent up-conversion of terahertz fields to multi-octave spectra in the mid-infrared and optical frequencies(9). Here we demonstrate that thin films of SiO2 exposed to intense, few-cycle to sub-cycle pulses give rise to wideband coherent EUV radiation extending in energy to about 40 electronvolts. Our study indicates the association of the emitted EUV radiation with intraband currents of multi-petahertz frequency, induced in the lowest conduction band of SiO2. To demonstrate the applicability of high-harmonic spectroscopy to solids, we exploit the EUV spectra to gain access to fine details of the energy dispersion profile of the conduction band that are as yet inaccessible by photoemission spectroscopy in wide-bandgap dielectrics. In addition, we use the EUV spectra to trace the attosecond control of the intraband electron motion induced by synthesized optical transients. Our work advances light-wave electronics(5,13-15) in condensed matter into the realm of multi-petahertz frequencies and their attosecond control, and marks the advent of solid-state EUV photonics.