Control of trion-to-exciton conversion in monolayer WS by orbital angular momentum of light.

Controlling the density of exciton and trion quasiparticles in monolayer two-dimensional (2D) materials at room temperature by nondestructive techniques is highly desired for the development of future optoelectronic devices. Here, the effects of different orbital angular momentum (OAM) lights on monolayer tungsten disulfide at both room temperature and low temperatures are investigated, which reveal simultaneously enhanced exciton intensity and suppressed trion intensity in the photoluminescence spectra with increasing topological charge of the OAM light. In addition, the trion-to-exciton conversion efficiency is found to increase rapidly with the OAM light at low laser power and decrease with increasing power.

Selective Photoexcitation of Finite-Momentum Excitons in Monolayer MoS by Twisted Light.

Twisted light carries a well-defined orbital angular momentum (OAM) of per photon. The quantum number of its OAM can be arbitrarily set, making it an excellent light source to realize high-dimensional quantum entanglement and ultrawide bandwidth optical communication structures. In spite of its interesting properties, twisted light interaction with solid state materials, particularly two-dimensional materials, is yet to be extensively studied experiments.

Anomalous lattice vibrations of CVD-grown monolayer MoS probed using linear polarized excitation light.

A novel physical phenomenon and advanced application have been explored in 2D low-dimensional van der Waals layered materials due to their reduced in-plane symmetry. The light-matter interaction is observed upon rapid characterization of the 2D material's crystal orientation. Here, the effects of the sample's rotation angle and the incident light's linear polarization angle on the Raman scattering of chemical vapor deposition (CVD)-grown monolayer MoS were investigated.