近日，德国罗斯托克大学的Dieter Bauer课题组成功利用相消干涉形成了固体高次谐波产生平台。相关研究成果已于2023年3月17日在国际权威学术期刊《物理评论A》上发表。
该课题组证明了固体高次谐波产生平台依赖于激光强度的截止频率，是由布里渊区的不同初始状态的电子发射的相消干涉形成的。这项工作中的计算是针对Su-Schrieffer-Heeger链的，但他们的发现也适用于其他双带体系。只有当布里渊区的采样足够细，或者等效地，位置空间中的有限链足够长时，相消干涉才完整的并形成截止频率。对于较粗糙的采样和较短的链，最小到最大带隙之间的所有谐波都会被发射。时频分析显示了某些轨迹是如何导致截止频率形成的。
据悉，在经常被研究的固体高次谐波产生的双带模型中，原则上，带间谐波可以从最小到最大带隙范围内存在。然而，已知存在一个依赖于激光强度的截止频率，除非电子探测整个布里渊区，否则该截止频率可能远低于最大带隙。
附：英文原文
Title: Formation of the solid-state high-order harmonic generation plateau through destructive interference
Author: Lina Bielke, Christoph Jür, Vincent Burgtorf, Dieter Bauer
Issue&Volume: 2023/03/17
Abstract: In frequently studied two-band models for solid-state high-order harmonic generation, interband harmonics, in principle, can range from the minimum to the maximum band gap. However, it is known that a laser-intensity-dependent cutoff exists that may be well below the maximum band gap unless the laser intensity is so high that the electrons explore the entire Brillouin zone. We show that this laser-intensity-dependent cutoff is formed by destructive interference of the emission of electrons starting at different initial states in the Brillouin zone. The calculations in this work are for Su-Schrieffer-Heeger chains, but our findings apply to other two-band systems as well. The destructive interference is complete and forms the cutoff only when the sampling of the Brillouin zone is fine enough or, equivalently, a finite chain is long enough in position space. For coarser sampling and shorter chains all harmonics between minimum and maximum band gap are emitted. A time-frequency analysis shows how certain trajectories are responsible for the formation of the cutoff.
DOI: 10.1103/PhysRevA.107.033111
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.107.033111
