Simultaneous observation of transverse and longitudinal photonic spin splitting in monolayer WSe2 via quantum weak measurement

Abstract

We report on the observation of longitudinal (in-plane) and transverse (out-of-plane) spin splitting of incident linearly polarized (p and s) light beams reflected at the interface of tungsten di-selenide, a monolayer transition metal dichalcogenide material deposited on a Si/SiO2 substrate, near the Brewster angle of incidence employing the quantum weak measurement technique. The amplified longitudinal and transverse shift values reach up to hundreds of micrometers. The transverse shift value, measured approximately at 400 μm, dominates over the longitudinal shift value at Brewster incidence. In this work, we found positive and negative shift values for the same angle of incidence but distinct polarization states revealing the explicit dependencies upon the angle of incidence and the post-selection angle. The modified weak measurement model provides an excellent interpretation of these experimental findings. This work, thus, provides novel insights into the effects of light–matter interactions and could find important applications in optical switches, nano-photonics, and the non-destructive study of material properties.