Photonic Topological Insulating Phase Induced Solely by Gain and Loss

TL;DR

This paper demonstrates a one-dimensional topological insulator phase in non-Hermitian optical lattices, induced solely by gain and loss control, leading to topological states without Hermitian bandgap requirements.

Contribution

It introduces a novel method to realize topological phases using gain and loss in optical systems, expanding the understanding of non-Hermitian topological phenomena.

Findings

Topological phase achieved solely by gain and loss control.

Bulk bandgap and topological edge states can be tuned via pumping.

Non-Hermitian topological numbers are clarified in gapless conditions.

Abstract

We reveal a one-dimensional topological insulating phase induced solely by gain and loss control in non-Hermitian optical lattices. The system comprises units of four uniformly coupled cavities, where successive two have loss, the others experience gain and they are balanced under two magnitudes. The gain and loss parts are effectively dimerized, and a bulk bandgap, topological transition, midgap topological edge and interface states in finite systems can all be achieved by controlled pumping. We also clarify non-Hermitian topological numbers and edge states in gapless conditions.