Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA.
Phys Rev Lett. 2023 Apr 21;130(16):166903. doi: 10.1103/PhysRevLett.130.166903.
Anomalous high-harmonic generation (HHG) arises in certain solids when irradiated by an intense laser field, originating from a Berry-curvature-induced perpendicular anomalous current. The observation of pure anomalous harmonics is, however, often prohibited by contamination from harmonics stemming from interband coherences. Here, we fully characterize the anomalous HHG mechanism, via development of an ab initio methodology for strong-field laser-solid interaction that allows a rigorous decomposition of the total current. We identify two unique properties of the anomalous harmonic yields: an overall yield increase with laser wavelength; and pronounced minima at certain laser wavelengths and laser intensities around which the spectral phases drastically change. Such signatures can be exploited to disentangle the anomalous harmonics from competing HHG mechanisms, and thus pave the way for the experimental identification and time-domain control of pure anomalous harmonics, as well as reconstruction of Berry curvatures.
当用强激光场辐照某些固体时，会产生反常高次谐波（HHG），其源于 Berry 曲率诱导的垂直反常电流。然而，由于源自带间相干的谐波的干扰，纯反常谐波的观察常常受到限制。在这里，我们通过开发用于强场激光-固体相互作用的从头算方法，对反常 HHG 机制进行了全面的描述，该方法允许对总电流进行严格的分解。我们确定了反常谐波产额的两个独特性质：随着激光波长的增加，总产额增加；在某些激光波长和激光强度下，出现明显的最小值，在这些波长和强度下，光谱相位会发生急剧变化。这些特征可用于将反常谐波与竞争的 HHG 机制区分开来，从而为实验识别和时域控制纯反常谐波以及 Berry 曲率的重建铺平道路。
