Topological hybrid silicon microlasers

Han Zhao,Liang Feng,Ramy El-Ganainy,Mohammad H Teimourpour,Henning Schomerus,Pei Miao,Simon Malzard

doi:10.1038/s41467-018-03434-2

Abstract

Topological physics provides a robust framework for strategically controlling wave confinement and propagation dynamics. However, current implementations have been restricted to the limited design parameter space defined by passive topological structures. Active systems provide a more general framework where different fundamental symmetry paradigms, such as those arising from non-Hermiticity and nonlinear interaction, can generate a new landscape for topological physics and its applications. Here, we bridge this gap and present an experimental investigation of an active topological photonic system, demonstrating a topological hybrid silicon microlaser array respecting the charge-conjugation symmetry. The created new symmetry features favour the lasing of a protected zero mode, where robust single-mode laser action in the desired state prevails even with intentionally introduced perturbations. The demonstrated microlaser is hybrid implemented on a silicon-on-insulator substrate, and is thereby readily suitable for integrated silicon photonics with applications in optical communication and computing.

Highlights

Topological physics provides a robust framework for strategically controlling wave confinement and propagation dynamics
The answers to these questions transform our understanding of topological robustness by revealing unique connections between topology and other types of fundamental symmetries arising from non-Hermiticity, opening the door for improving robust optical device functionality, a key incentive in the research of integrated photonics over the past few decades
We experimentally explore the utility of topological concepts to active systems and demonstrate an on-chip hybrid silicon microlaser whose mode competition naturally favours robust laser action arising from a topological defect

Summary

Introduction

Topological physics provides a robust framework for strategically controlling wave confinement and propagation dynamics. Considerable effort has been made to transplant the topological notions into lasing systems[14,15,16], in which topological robustness collides with other physical considerations, posing diverse unexplored fundamental questions about the interplay between topological features, nonHermitian physics[17,18,19,20,21,22,23,24], and the break-down of the superposition principle The answers to these questions transform our understanding of topological robustness by revealing unique connections between topology and other types of fundamental symmetries arising from non-Hermiticity (naturally pertinent to active systems), opening the door for improving robust optical device functionality, a key incentive in the research of integrated photonics over the past few decades. Different from a recent breakthrough demonstration of topological edgemode lasing where the edge state is selectively excited[35], our microlaser is based on the strategic combination of nonHermitian and topological symmetries, supporting arbitrary pumping strategies (either uniform or selective pumping)

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Results

Conclusion