Nonlinearity-induced photonic topological insulator

TL;DR

This paper demonstrates a photonic topological insulator where nonlinearity induces a topological phase transition, enabling power-dependent unidirectional edge channels in a photonic system.

Contribution

It introduces the first experimental realization of a nonlinear topological insulator in a photonic platform driven by nonlinearity.

Findings

Nonlinear regime induces topological phase transition.

Power threshold triggers topological edge states.

Potential for on-demand topological photonic devices.

Abstract

The hallmark feature of topological insulators renders edge transport virtually impervious to scattering at defects and lattice disorder. In our work, we experimentally demonstrate a topological system, using a photonic platform, in which the very existence of the topological phase is brought about by nonlinearity. Whereas in the linear regime, the lattice structure remains topologically trivial, light beams launched above a certain power threshold drive the system into its transient topological regime, and thereby define a nonlinear unidirectional channel along its edge. Our work studies topological properties of matter in the nonlinear regime, and may pave the way towards compact devices that harness topological features in an on-demand fashion.