Chiral nonlinear polaritonics with van der Waals metasurfaces

TL;DR

A new chiral metasurface enables selective polariton formation and chiral light interactions for advanced photonic applications.

Contribution

A monolithic TMDC metasurface with broken symmetry enables maximal chirality for polaritonics and nonlinear optics.

Findings

The metasurface supports chiral exciton-polaritons with maximal chirality up to 20° oblique incidence.

Chiral strong coupling is observed in third-harmonic generation experiments.

The platform is suitable for nonreciprocal photonic devices and valleytronics.

Abstract

Chiral optical cavities are crucial for the development of nonequilibrium quantum materials by discriminating and selectively coupling to light of a specific circular polarization, but fundamentally cannot be realized with conventional mirror cavities. Here, we demonstrate this unique functionality by developing a monolithic transition metal dichalcogenide (TMDC) metasurface with broken out-of-plane symmetry, allowing for the selective formation of self-hybridized chiral exciton-polaritons. Our metasurface maintains maximal chirality for oblique incidence up to 20°, thereby outperforming all previously known designs. Moreover, we study the chiral strong-coupling regime in nonlinear experiments and reveal polaritonic signatures in chiral third-harmonic generation. Our results position maximally chiral van der Waals (vdW) metasurfaces as a versatile platform for tunable chiral polaritonics with applications in nonreciprocal photonic devices and valleytronics.

A maximally chiral metasurface enables polariton-driven third-harmonic generation with controllable light helicity.

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