Dirac-vortex topological cavity

TL;DR

This paper introduces a topological cavity design based on a 2D honeycomb photonic crystal with a vortex Dirac mass, enabling tunable, robust, and versatile laser modes with potential applications in stable single-mode photonic devices.

Contribution

It generalizes 1D topological cavity concepts to 2D honeycomb structures, demonstrating experimentally a novel Dirac-vortex cavity with unique mode properties.

Findings

Tunable mode area over several orders of magnitude

Arbitrary mode degeneracy achieved

Large free-spectral-range and low-divergence vector-beam output

Abstract

Cavity design is crucial for single-mode semiconductor lasers such as the distributed feedback (DFB) and vertical-cavity surface-emitting lasers (VCSEL). By recognizing that both optical resonators feature a single mid-gap mode localized at the topological defect in a one-dimensional (1D) lattice, we generalize the topological cavity design into 2D using a honeycomb photonic crystal with a vortex Dirac mass -- the analog of Jackiw-Rossi zero modes. We theoretically predict and experimentally demonstrate that such a Dirac-vortex cavity can have a tunable mode area across a few orders of magnitudes, arbitrary mode degeneracy, robustly large free-spectral-range, vector-beam output of low divergence, and compatibility with high-index substrates. This topological cavity could enable photonic crystal surface-emitting lasers (PCSEL) with stabler single-mode operation.