Controlling exciton emission direction through Optical spin-orbit interaction with metallic nanogrooves

The recently introduced class of two-dimensional materials, monolayer Transition Metal Dichalcogenides (TMDs), are emerging as highly promising candidates to enhance data transfer capacity in the field of Valleytronics. Strong “atomic spin-orbit interaction” in monolayer TMDs locks spin of electrons to degenerate valleys with different momenta. These locked valley-spin pairs respond differently to different circular polarizations of light. However, this feature vanishes at room temperature. To address this issue, the coupling between the exciton emissions and photonic modes are under extensive investigation.
This dissertation explores the control over TMD valley-polarized emission by coupling the exciton emission to the plasmonic mode. Specifically, we take advantage of the strong coupling between monolayer WS2 and metallic nanogrooves to enhance information routing, thereby achieving higher data capacity.
The first part of this study is focused on analyzing the interdependence between the nanogroove parameters and the coupling condition. In the second part, we will demonstrate the k-space separation of valley excitons in monolayer TMDs through the "optical spin-orbit interaction." This separation implies that the helicity of photons determines a preferred emission direction.
This research can serve as a guideline for designing structures and pave the way to transport and read out the spin and valley degrees of freedom in two-dimensional materials. By addressing current challenges in the field of Valleytronics, it offers guidance for future advancements in this area.