Polarized photoluminescence spectroscopy in WS2, WSe2 atomic layers and heterostructures by cylindrical vector beams* *Project supported by the National Natural Science Foundation of China (Grant Nos. 91850116, 51772084, 52022029, and U19A2090), Hunan Provincial Natural Science Foundation of China (Grant Nos. 2018RS3051 and 2018WK4004), and the Key Program of the Hunan Provincial Science and Technology Department, China (Grant No. 2019XK2001).

Abstract

Due to the large exciton binding energy, two-dimensional (2D) transition metal dichalcogenides (TMDCs) provide an ideal platform for studying excitonic states and related photonics and optoelectronics. Polarization states lead to distinct light-matter interactions which are of great importance for device applications. In this work, we study polarized photoluminescence spectra from intralayer exciton and indirect exciton in WS2 and WSe2 atomic layers, and interlayer exciton in WS2/WSe2 heterostructures by radially and azimuthally polarized cylindrical vector laser beams. We demonstrated the same in-plane and out-of-plane polarization behavior from the intralayer and indirect exciton. Moreover, with these two laser modes, we obtained interlayer exciton in WS2/WSe2 heterostructures with stronger out-of-plane polarization, due to the formation of vertical electric dipole moment.