Topological Valley Hall Edge State Lasing

TL;DR

This paper introduces a novel class of topological valley Hall edge state lasers that operate without external magnetic fields, demonstrating robustness and stability even in complex geometries and in the presence of disorder.

Contribution

It proposes a new topological laser design based on valley Hall edge states that does not require magnetic fields or dynamic modulation, expanding practical topological laser applications.

Findings

Lasing occurs at domain walls between honeycomb waveguide arrays with broken inversion symmetry.

Lasing states are stable and can circumvent sharp corners without scattering.

The structure supports robust lasing in both periodic and finite geometries.

Abstract

Topological lasers based on topologically protected edge states offer unique features and enhanced robustness of operation in comparison with conventional lasers, even in the presence of disorder, edge deformation, and localized defects. Here we propose a new class of topological lasers arising from the valley Hall edge states, which does not require external magnetic fields or dynamical modulations of the device parameters. Specifically, topological lasing occurs at domain walls between two honeycomb waveguide arrays with broken spatial inversion symmetry. Two types of valley Hall edge lasing modes are found by shaping the gain landscape along the domain walls. In the presence of uniform losses and two-photon absorption, lasing in edge states results in the formation of stable nonlinear dissipative excitations localized on the edge of the structure, even if it has complex geometry and even if it is finite. Robustness of lasing states is demonstrated in both periodic and finite structures, where such states can circumvent sharp corners without scattering loss or radiation into the bulk. The photonic structure and mechanism proposed here for topological lasing is fundamentally different from those previously demonstrated topological lasers and can be used for fabrication of practical topological lasers of various geometries.