Scientists used silver sawtooth nano clamp arrays to generate valley-coherent photoluminescence in two-dimensional tungsten disulfide sheets at room temperature. So far, this can only be achieved at shallow temperature. Coherent light can be used to stores or transmit information in quantum electronics. This plasmon exciton hybrid device has excellent application prospects in integrated nanophotonics (photonics-based electronics).
Tungsten disulfide has interesting electronic properties and can be used as a two-dimensional material. The electronic structures of a single layer of tungsten disulfide shows two sets of energy lowest points (valleys). One possible application is photonics because it can emit circularly polarized light that is valley-dependent, which is a new degree of freedom in processing information. However, electric valley electronics requires coherent and polarized light. Unfortunately, previous research shows that at room temperature, the photoluminescence polarization of tungsten disulfide is almost random. The unique feature of tungsten disulfide is that the two valleys are not precisely the same.
This means that to produce linearly polarized light, the two valleys must respond uniformly to provide a view in photoluminescence. However, inter-valley scattering at room temperature mostly destroys coherence, so significant adhesion can only be achieved at shallow temperatures close to zero. Therefore, scientists have tried a different method to create linearly polarized light in the form of silver sawtooth nano clamp arrays using plasma subsurfaces. This material interacts energetically with tungsten disulfide.
It can transfer the resonance caused by light in the form of an electromagnetic field in the metal and enhance the interaction between light and matter. By adding a thin layer of silver subsurface on the surface of the single-layer tungsten disulfide powder, the linear polarization caused by valley coherence at room temperature increases to about 27%. This room-temperature performance is even better than the valley polarization measured at shallow temperatures in many previous reports. Adding the zigzag plasmon resonance anisotropy to the optical response of tungsten disulfide can further increase the linear polarization to 80%. This means that scientists can now induce linearly polarized photoluminescence in this material.
