Strong-field and attosecond physics in solids
Strong-field and attosecond physics in solids
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DOI：
10.1088/0953-4075/47/20/204030
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发表时间：
2014-10-28
影响因子：
1.6
通讯作者：
Reis, David A.
中科院分区：
文献类型：
--
作者：
Ghimire, Shambhu;Ndabashimiye, Georges;Reis, David A.
我们回顾了凯尔迪什隧道极限附近大块透明固体中的强场和阿秒过程的状态。对于足够高的场和低频激励，电介质的光学和电子特性可以在施加的脉冲内瞬时且可逆地改变。 Ghimire 等人 (2011 Phys. Rev. Lett. 107 167407) 在强中红外场中的 ZnO 晶体的光子辅助隧道实验中发现了非抛物线带效应。使用相同的 ZnO 晶体，Ghimire 等人 (2011 Nat. Phys. 7 138-41) 报告了首次观察到非微扰高次谐波，其远高于带隙延伸至真空紫外。 Schubert 等人最近的实验 (2014 Nat. Photonics 8 119-23) 显示了强场 30 THz 驱动的 GaSe 晶体中谐波谱中的载流子包络相位依赖性，这是子周期电子动力学在固态谐波产生中作用的最直接证据。由于晶体的高密度和周期性，谐波产生机制与气相不同。例如，这导致高能截止与施加场的线性相关性，与气相中的二次相关性相反。如果谐波光谱可以扩展到极紫外 (XUV)，那么低于 100 阿秒的脉冲就有可能成为可能。在这里，我们报告了块状 MgO 晶体中产生的谐波，当由类似 35 fs、800 nm 的脉冲（聚焦到类似 1 V 埃(-1) 峰值场）驱动时，谐波扩展至类似 26 eV。基本的强场和阿秒响应还会导致 Wannier-Stark 局域化和可逆半金属化，如 Schiffrin 等人 (2013 Nature 493 70-4) 和 Schultze 等人 (2013 Nature 493 75-8) 在熔融石英上进行的 XUV 吸收和光电流实验的亚光循环行为中所见。这些研究正在增进我们对固体中的基本强场和阿秒物理的理解，以及紧凑相干短波长源和超高速光电子学的潜在应用。
We review the status of strong-field and attosecond processes in bulk transparent solids near the Keldysh tunneling limit. For high enough fields and low-frequency excitations, the optical and electronic properties of dielectrics can be transiently and reversibly modified within the applied pulse. In Ghimire et al (2011 Phys. Rev. Lett. 107 167407) non-parabolic band effects were seen in photon-assisted tunneling experiments in ZnO crystals in a strong mid-infrared field. Using the same ZnO crystals, Ghimire et al (2011 Nat. Phys. 7 138-41) reported the first observation of non-pertubative high harmonics, extending well above the bandgap into the vacuum ultraviolet. Recent experiments by Schubert et al (2014 Nat. Photonics 8 119-23) showed a carrier envelope phase dependence in the harmonic spectrum in strong-field 30 THz driven GaSe crystals which is the most direct evidence yet of the role of sub-cycle electron dynamics in solid-state harmonic generation. The harmonic generation mechanism is different from the gas phase owing to the high density and periodicity of the crystal. For example, this results in a linear dependence of the high-energy cutoff with the applied field in contrast to the quadratic dependence in the gas phase. Sub-100 attosecond pulses could become possible if the harmonic spectrum can be extended into the extreme ultraviolet (XUV). Here we report harmonics generated in bulk MgO crystals, extending to similar to 26 eV when driven by similar to 35 fs, 800 nm pulses focused to a similar to 1 V angstrom(-1) peak field. The fundamental strong-field and attosecond response also leads to Wannier-Stark localization and reversible semimetallization as seen in the sub-optical cycle behavior of XUV absorption and photocurrent experiments on fused silica by Schiffrin et al (2013 Nature 493 70-4) and Schultze et al (2013 Nature 493 75-8). These studies are advancing our understanding of fundamental strong-field and attosecond physics in solids with potential applications for compact coherent short-wavelength sources and ultra-high speed optoelectronics.