Complex Edge-State Phase Transitions in 1D Topological Laser Arrays

TL;DR

This paper demonstrates lasing in topological edge states of a 1D active resonator array, revealing complex phase transitions influenced by topology and symmetry that affect emission spectra and mode competition.

Contribution

First experimental observation of topological edge-state lasing in a 1D active array, showing how non-Hermitian topology induces complex phase transitions affecting laser operation.

Findings

Lasing occurs in topological edge states of a 1D array.

Complex phase transitions alter emission spectra and mode competition.

Topology influences the lasing behavior and mode selection.

Abstract

We report the first observation of lasing in topological edge states in a 1D Su-Schrieffer-Heeger active array of resonators. We show that in the presence of chiral-time ($\mathcal{CT}$) symmetry, this non-Hermitian topological structure can experience complex phase transitions that alter the emission spectra as well as the ensued mode competition between edge and bulk states. The onset of these phase transitions is found to occur at the boundaries associated with the complex geometric phase- a generalized version of the Berry phase in Hermitian settings. Our experiments and theoretical analysis demonstrate that the topology of the system plays a key role in determining its operation when it lases: topologically controlled lasing.