Room-temperature valley-selective emission in Si-MoSe2 heterostructures enabled by high-quality-factor chiroptical cavities

TL;DR

This paper demonstrates room-temperature valley-selective emission in MoSe2 monolayers using high-Q chiral metasurfaces, enabling efficient valley polarization without polarization-dependent excitation.

Contribution

It introduces a novel chiral resonant metasurface platform that achieves high Q-factors and strong chiroptical effects at room temperature for valleytronics applications.

Findings

Achieved a record high degree of circular polarization (DOP) of 0.5 at room temperature.

Enhanced valley-specific radiative transition rates by approximately 13 times.

Fabricated Si chiral metasurfaces with Q-factors up to 450 at visible wavelengths.

Abstract

Transition metal dichalcogenides possess valley pseudospin, enabling coupling between photon spin and electron spin for classical and quantum information processing. However, rapid valley-dephasing processes have impeded the development of scalable, high-performance valleytronic devices operating at room temperature. Here we demonstrate that a chiral resonant metasurface can enable room-temperature valley-selective emission in MoSe2 monolayers independent of excitation polarization. This platform provides circular eigen-polarization states with a high quality factor (Q-factor) and strong chiral near-field enhancement. The fabricated Si chiral metasurfaces exhibit chiroptical resonances with Q-factors up to 450 at visible wavelengths. We reveal degrees of circular polarization (DOP) reaching a record high of 0.5 at room temperature. Our measurements show that the high DOP can be attributed to the significantly increased chiroptical local density of states, which enhances valley-specific radiative transition rates by a factor of ~13. Our work could facilitate the development of ultracompact chiral classical and quantum light sources.