Topological Chiral-Gain in a Berry Dipole Material

TL;DR

This paper reveals the topological origin of chiral gain in Berry dipole materials, demonstrating how static electric fields induce topological bandgaps with unidirectional edge states that can be used for lossless photonic applications.

Contribution

It uncovers the topological nature of chiral gain in non-equilibrium systems and shows how electric bias creates topological bandgaps supporting unidirectional edge states with dissipative properties.

Findings

Topological bandgaps support unidirectional edge states.

Chiral gain enables boundary-confined lasing with orbital angular momentum.

Potential for lossless, unidirectional photonic waveguides.

Abstract

Recent studies have shown that non-equilibrium optical systems under static electric fields offer a pathway to realize chiral gain, where the non-Hermitian response of a material is controlled by the spin angular momentum of the wave. In this work, we uncover the topological nature of chiral gain and demonstrate how a static electric bias induces topological bandgaps that support unidirectional edge states at the material boundaries. Curiously, in our system, these topological edge states consistently exhibit dissipative properties. We further show that, by operating outside the topological gap, the chiral gain can be leveraged to engineer boundary-confined lasing modes with orbital angular momentum, locked to the orientation of the applied electric field. Our results open new possibilities for loss-compensated photonic waveguides, enabling advanced functionalities such as unidirectional, lossless edge-wave propagation and the generation of structured light with intrinsic orbital angular momentum.