A high-performance topological bulk laser based on band-inversion-induced reflection

• Published in: Nature nanotechnology Vol. 15; no. 1; pp. 67 - 72
• Main Authors: Shao, Zeng-Kai, Chen, Hua-Zhou, Wang, Suo, Mao, Xin-Rui, Yang, Zhen-Qian, Wang, Shao-Lei, Wang, Xing-Xiang, Hu, Xiao, Ma, Ren-Min
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-01-2020; Nature Publishing Group
• Subjects: 140/125; 142/126; 639/624/1020/1093; 639/925/927/1021; Chemistry and Materials Science; Conductors; Crystals; Emissions; Free-space optical communication; Industry standards; Laser applications; Lasers; Lasing; Materials Science; Nanotechnology; Nanotechnology and Microengineering; Photonic crystals; Reflection; Room temperature; Spectroscopy; Temperature requirements; Topological insulators; Topology
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/s41565-019-0584-x

Topological insulators are materials that behave as insulators in the bulk and as conductors at the edge or surface due to the particular configuration of their bulk band dispersion. However, up to date possible practical applications of this band topology on materials’ bulk properties have remained abstract. Here, we propose and experimentally demonstrate a topological bulk laser. We pattern semiconductor nanodisk arrays to form a photonic crystal cavity showing topological band inversion between its interior and cladding area. In-plane light waves are reflected at topological edges forming an effective cavity feedback for lasing. This band-inversion-induced reflection mechanism induces single-mode lasing with directional vertical emission. Our topological bulk laser works at room temperature and reaches the practical requirements in terms of cavity size, threshold, linewidth, side-mode suppression ratio and directionality for most practical applications according to Institute of Electrical and Electronics Engineers and other industry standards. We believe this bulk topological effect will have applications in near-field spectroscopy, solid-state lighting, free-space optical sensing and communication.
The interface between photonic crystals with distinct in-band topologies confines electromagnetic modes and gives rise to lasing emission in the bulk.