Anomalous Circularly Polarized Light Emission induced by the Optical Berry Curvature Dipole

TL;DR

This paper introduces a novel type of circularly polarized light emission that depends on emission and current directions, driven by the optical Berry curvature dipole in certain materials, with potential optoelectric applications.

Contribution

It reveals that circularly polarized light emission can be direction-dependent and topologically driven, challenging the conventional belief that chirality solely determines handedness.

Findings

High circular polarization ratio in monolayer WS₂

Direction-dependent circular polarization in emission

Optical Berry curvature dipole underpins ACPLE

Abstract

The ability to selectively excite light with fixed handedness is crucial for circularly polarized light emission. It is commonly believed that the luminescent material chirality determines the emitted light handedness, regardless of the light emitting direction. In this work, we propose an anomalous circular polarized light emission (ACPLE) whose handedness actually relies on the emission direction and current direction in electroluminescence. In a solid semiconductor, the ACPLE originates in the band structure topology characterized by the optical Berry curvature dipole. ACPLE exists in inversion-symmetry breaking materials including chiral materials. We exemplify the ACPLE by estimating the high circular polarization ratio in monolayer WS$_2$. In addition, the ACPLE can be further generalized to magnetic semiconductors in which the optical Berry curvature plays a leading role instead. Our finding reveals intriguing consequences of band topology in light emission and promises optoelectric applications.