Circular Dichroism Control of Tungsten Diselenide (WSe2) Atomic Layers with Plasmonic Metamolecules

Controlling circularly polarized states of light is critical to the development of functional devices for key and emerging applications such as display technology and quantum communication, and the compact circular polarization-tunable photon source is one critical element to realize the applications in the chip-scale integrated system. The atomic layers of transition metal dichalcogenide (TMDC) exhibit intrinsic circularly polarized emissions and are potential chiroptical materials for ultrathin circularly polarized photon sources. In this work, we demonstrated circularly polarized photon sources of TMDC with device thicknesses approximately 50 nm. Circularly polarized photoluminescence from atomic layers of tungsten diselenide (WSe) was precisely controlled with chiral meta-molecules, and the optical chirality of WSe was enhanced more than 4 times by integrating with the meta-molecules. Both the enhanced and reversed circular dichroisms had been achieved. Through integrations of the novel gain material and plasmonic structure which are both low dimensional, a compact device capable of efficiently manipulating emissions of circularly polarized photon was realized. These ultrathin devices are suitable for important applications such as the optical information technology and chip-scale bio-sensing.