Valley-based directional emission controlled by plasmonic nanostructure​

Two-dimensional semiconductors such as monolayer transition metal dichalcogenides (TMDs) exhibits remarkable optical properties such as robust valley polarization, making them ideal for optoelectronic and valleytronic devices. Manipulating the valley polarization by optical method is the key to realize valleytronic devices. Here, we demonstrate a resonant plasmonic nanostructure designed to spatially separate the emissions from different valleys of the WSe2 monolayer at cryogenic temperature. By changing the helicity of excitation, we show the directionality control of valley-based emission. Our hybrid nanostructure exhibits the possibility to realise the valleytronic devices.