Topological light-trapping on a dislocation

TL;DR

This paper introduces a novel topological mechanism called dual-topology that enables robust light-trapping in lower-dimensional photonic structures, demonstrated through the experimental realization of a localized Jackiw-Rebbi soliton mode on a dislocation.

Contribution

It reveals a new dual-topology concept combining wavevector and real-space topology to achieve topologically protected localized photonic modes in 2D photonic crystals.

Findings

Experimental observation of a topologically protected 0D localized mode.

The localized mode is robust against perturbations.

The mode is a Jackiw-Rebbi soliton localized on a dislocation.

Abstract

Topology has been revealed to play a fundamental role in physics in the past decades. Topological insulators have unconventional gapless edge states where disorder-induced back-scattering is suppressed. In photonics, such edge states lead to unidirectional waveguides which are useful for integrated photonic chips. Cavity modes, another type of fundamental components in photonic chips, however, are not protected by band topology because of their lower dimensions. Here we demonstrate that concurrent wavevector-space and real-space topology, dubbed as the "dual-topology", can lead to light-trapping in lower-dimensions. The resultant photonic bound state emerges as a Jackiw-Rebbi soliton mode localized on a dislocation in a two-dimensional (2D) photonic crystal, as predicted theoretically and discovered experimentally. Such a strongly-confined 0D localized mode, which is solely due to the topological mechanism, is found to be robust against perturbations. Our study unveils a new mechanism for topological light-trapping in lower-dimensions, which is valuable for fundamental physics and a variety of applications in photonics.