Laser-patterned submicron Bi2Se3-WS2 pixels with tunable circular polarization at room temperature

TL;DR

This study presents a laser-patterned Bi2Se3-WS2 heterostructure capable of tunable circular and valley polarization at room temperature, with stable, reversible, and spatially confined optical property modifications for potential spintronics and quantum applications.

Contribution

It introduces a novel laser-patterning technique to control polarization properties in Bi2Se3-WS2 heterostructures with high spatial resolution and stability, enabling reconfigurable optoelectronic functionalities.

Findings

Achieved 39.4% control over circular polarization.

Demonstrated stable modifications lasting over 334 days.

Reversible polarization tuning via laser exposure in vacuum.

Abstract

Characterizing and manipulating the circular polarization of light is central to numerous emerging technologies, including spintronics and quantum computing. Separately, monolayer tungsten disulfide (WS2) is a versatile material that has demonstrated promise in a variety of applications, including single photon emitters and valleytronics. Here, we demonstrate a method to tune the photoluminescence (PL) intensity (factor of x161), peak position (38.4meV range), circular polarization (39.4% range), and valley polarization of a Bi2Se3-WS2 2D heterostructure using a low-power laser (0.762uW) in ambient. Changes are spatially confined to the laser spot, enabling submicron (814nm) features, and are long-term stable (>334 days). PL and valley polarization changes can be controllably reversed through laser exposure in vacuum, allowing the material to be erased and reused. Atmospheric experiments and first-principles calculations indicate oxygen diffusion modulates the exciton radiative vs. non-radiative recombination pathways, where oxygen absorption leads to brightening, and desorption to darkening.