Unlocking Wavefront Manipulation in Exciton-Polaritons by Structuring WS₂ as Phase Gradient Metasurfaces

Area of Science:

• Condensed Matter Physics
• Optics
• Materials Science

Background:

• Exciton-polaritons (EPs) are hybrid light-matter quasiparticles with nanoscale field confinement.
• Controlling the phase of EPs at the pixel level for advanced light manipulation remains a significant challenge.

Purpose of the Study:

• To demonstrate wavefront shaping of exciton-polaritons using geometrically tailored tungsten disulfide (WS2) metasurfaces.
• To achieve nanoscale spatial phase control of EPs for novel optical applications.

Main Methods:

• Fabrication of WS2 metasurfaces with elliptical nanodisks supporting localized Mie resonances.
• Coupling of Mie resonances with WS2 excitons to form self-hybridized EPs with significant Rabi splitting (~150 meV).
• Utilizing anisotropic nanoantenna geometry for high birefringence and cross-polarization conversion.

Main Results:

• Demonstrated pixelated phase control of EPs by spatially arranging meta-atoms based on the geometric phase principle.
• Achieved efficient cross-polarization conversion due to high birefringence of the metasurface.
• Experimentally realized deflection and focusing of the EP beam with subwavelength resolution.

Conclusions:

• The integration of subwavelength polariton confinement with metasurface wavefront engineering offers a novel approach for manipulating light at the nanoscale.
• This work lays the foundation for developing compact and multifunctional polaritonic devices with unprecedented control over light properties.