Tancogne-Dejean Nicolas, Mücke Oliver D, Kärtner Franz X, Rubio Angel
Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany.
European Theoretical Spectroscopy Facility (ETSF), Luruper Chaussee 149, 22761 Hamburg, Germany.
Phys Rev Lett. 2017 Feb 24;118(8):087403. doi: 10.1103/PhysRevLett.118.087403.
An accurate analytic model describing the microscopic mechanism of high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that (i) the emitted HHG spectra are highly anisotropic and laser-polarization dependent even for cubic crystals; (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential; the yield is increased for heavier atoms; and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the laser polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
我们推导了一个准确的解析模型，用于描述固体中高次谐波产生（HHG）的微观机制。在含时密度泛函框架内进行的大量第一性原理模拟证实了该模型的结论。我们的结果表明：（i）即使对于立方晶体，发射的HHG光谱也是高度各向异性的，并且依赖于激光偏振；（ii）电子 - 原子核势的不均匀性增强了谐波发射；对于较重的原子，产率增加；（iii）截止光子能量与驱动波长无关。此外，我们表明仅根据体晶体的电子能带结构知识就有可能预测其产生最佳HHG时的激光偏振。我们的结果为通过设计固体的能带结构来更好地控制和优化HHG铺平了道路。
