Topological insulator vertical-cavity laser array
Alex Dikopoltsev, Tristan H. Harder, Eran Lustig, O. A. Egorov, Johannes Beierlein, A. Wolf, Yaakov Lumer, Monika Emmerling, Christian Schneider, Sven Höfling, Mordechai Segev, Sebastian Klembt
Abstract
Topological insulator lasers are arrays of semiconductor lasers that exploit fundamental features of topology to force all emitters to act as a single coherent laser. In this study, we demonstrate a topological insulator vertical-cavity surface-emitting laser (VCSEL) array. Each VCSEL emits vertically, but the in-plane coupling between emitters in the topological-crystalline platform facilitates coherent emission of the whole array. Our topological VCSEL array emits at a single frequency and displays interference, highlighting that the emitters are mutually coherent. Our experiments exemplify the power of topological transport of light: The light spends most of its time oscillating vertically, but the small in-plane coupling is sufficient to force the array of individual emitters to act as a single laser.