Electrically pumped topological laser with valley edge modes
Electrically pumped topological laser with valley edge modes
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DOI：
10.1038/s41586-020-1981-x
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发表时间：
2020-02-01
期刊：
影响因子：
64.8
通讯作者：
Wang, Qi Jie
中科院分区：
文献类型：
--
作者：
Zeng, Yongquan;Chattopadhyay, Udvas;Wang, Qi Jie
量子级联激光器是一种紧凑的电泵浦光源，位于电磁光谱(1，2)中具有重要技术意义的中红外和太赫兹区域。最近，拓扑学(3)的概念已经从凝聚态物理扩展到光子学(4)，产生了一种新型的激光(5-8)，它使用拓扑保护的光子模式，可以有效地绕过角落和缺陷(4)。以前的拓扑激光器演示需要外部激光光源来进行光抽运，并且工作在传统的光学频率区域(5-8)。在这里，我们展示了一种基于拓扑保护的谷边缘态(9-11)的电泵浦太赫兹量子级联激光器。与依赖大规模特征来提供拓扑保护的拓扑激光器不同，我们的紧凑型设计利用了光子晶体(10，11)中的山谷自由度，类似于二维有间隙的山谷电子材料(12)。具有规则间隔发射峰的激光发生在尖角三角形腔中，即使在底层结构中引入微扰，这是因为存在拓扑保护的谷缘状态，这些状态在腔周围循环而不经历局域化。通过在拓扑腔中加入不同的外耦器，研究了拓扑模的特性。基于谷边缘态的激光器可能为电驱动激光光源中的拓扑保护的实际应用开辟道路。
Quantum cascade lasers are compact, electrically pumped light sources in the technologically important mid-infrared and terahertz region of the electromagnetic spectrum(1,2). Recently, the concept of topology(3) has been expanded from condensed matter physics into photonics(4), giving rise to a new type of lasing(5-8) using topologically protected photonic modes that can efficiently bypass corners and defects(4). Previous demonstrations of topological lasers have required an external laser source for optical pumping and have operated in the conventional optical frequency regime(5-8). Here we demonstrate an electrically pumped terahertz quantum cascade laser based on topologically protected valley edge states(9-11). Unlike topological lasers that rely on large-scale features to impart topological protection, our compact design makes use of the valley degree of freedom in photonic crystals(10,11), analogous to two-dimensional gapped valleytronic materials(12). Lasing with regularly spaced emission peaks occurs in a sharp-cornered triangular cavity, even if perturbations are introduced into the underlying structure, owing to the existence of topologically protected valley edge states that circulate around the cavity without experiencing localization. We probe the properties of the topological lasing modes by adding different outcouplers to the topological cavity. The laser based on valley edge states may open routes to the practical use of topological protection in electrically driven laser sources.