Experimental Study of Few‐Layer Graphene: Optical Anisotropy and Pseudo‐Brewster Angle Shift in Vacuum Ultraviolet Spectral Range

The optical properties of mono- and trilayer graphene on SiO2/Si substrate are studied at hydrogen Lyman-alpha (121.6nm) spectral line for the first time. The optical anisotropy of graphene at this wavelength is experimentally demonstrated by retrieving the anisotropic "effective" optical constants. The results confirm that the axis of symmetry is nearly perpendicular to the surface and coherently related to the pi-orbitals' structural orientation. Furthermore, it is observed that graphene strongly affects the performances of the substrate by inducing a pseudo-Brewster angle downshift, which depends on the number of graphene layers. This finding is in contrast with what occurs in the visible spectral range, where the upshift of the pseudo-Brewster angle is experienced in similar samples.