Magnetically tunable telecom emission from Er3+ ions in layered WS2

TL;DR

This study demonstrates that Er3+ ions embedded in layered WS2 can have their telecom-band emission properties tuned by magnetic fields, leveraging crystal-field effects and photonic environment interactions.

Contribution

It reveals how magnetic fields influence Er3+ emission in WS2, combining experimental observations with theoretical modeling to understand the underlying mechanisms.

Findings

Magnetic fields cause emission dimming and dipole rotation in Er3+ in WS2.

Zeeman-induced mixing of crystal-field levels alters optical dipoles.

Layered WS2 enables magnetic tuning of telecom emission via crystal and photonic effects.

Abstract

Erbium ions (Er3+) provide a telecom-band optical transition with strong magnetic-dipole character, making them attractive for quantum communication and spin-photon interfaces. Identifying host environments that combine low decoherence with photonic compatibility, however, remains a central challenge. Here we investigate Er3+ emission in tungsten disulfide (WS2) flakes, a layered host offering low nuclear-spin density and narrow telecom emission. Using time- and polarization-resolved photoluminescence under modest magnetic fields (< 0.2 T), we observe pronounced dimming, lifetime extension, and rotation of the emission dipole when the field has an out-of-plane component, whereas in-plane fields produce little change. Effective model calculations of Er3+ in monolayer WS2 parametrized from density functional theory indicate that these effects arise primarily from Zeeman-induced mixing of near-degenerate crystal-field sublevels, which modifies the magnitude and orientation of the optical transition dipole moments. Comparative measurements in flakes of different thickness and numerical estimates of the local density of optical states further suggest a secondary contribution from dipole coupling to the anisotropic photonic environment of thin WS2 layers. These findings identify layered WS2 as a platform where magnetic fields can tune telecom emission through an interplay of crystal-field physics and anisotropic photonic coupling.