Extended Data Fig. 5: Energy dispersion and spin texture of the topological surface states in 2D Brillouin zone.

a, Schematic of the spin texture of the surface states near the Γ point, For the conduction band, the helicity is left handed, while for the valence band is right handed. b, Band structure of the surface states including hexagonal warping effect. c, The 2D surface Brillouin zone and its orientation in laboratory coordinate, in which k_x, k_y are along the \({\bar{\mathrm \Gamma }} - {\bar{\mathrm K}}\) and \({\bar{\mathrm \Gamma }} - {\bar{\mathrm M}}\) directions, respectively, k_X, k_Y are along the horizontal and vertical direction in laboratory frame, respectively. The red arrow illustrates the pump pulse in s-polarization. The angle between \({\bar{\mathrm \Gamma }} - {\bar{\mathrm K}}\) direction and driven field is defined as θ = π/2 − φ.