Figure 1

Schematic diagram of the polarization configurations in our polarized Raman spectroscopy. (a) normal laser incidence (θ = 0), where both the vertical polarization (VV) and the horizontal polarization (HH) of the laser light are parallel to the graphene plane, (b) oblique laser incidence (θ ≠ 0) where the vertical polarization is parallel to the graphene plane (in-plane configuration) but the horizontal polarization is not parallel to the graphene plane (out-of-plane configuration). The inset shows the top view of the graphene plane and the polarization vector in the out-of-plane configuration in an oblique laser incidence, where the polarization projected onto the graphene plane is E _m e ^iωtcosθ.