Extended Data Fig. 1: Sample orientation.
From: Lightwave valleytronics in a monolayer of tungsten diselenide
a, Azimuthal scan of the second-harmonic intensity polarized parallel to the excitation pulse, ISHG,|| (blue curve), revealing the armchair direction at a crystal angle of φ = 30°. The dashed line marks the expected scaling proportional to sin2(3φ). Around the polar diagram, the hexagonal Brillouin zone of WSe2 is depicted with the high-symmetry points. b, Optical microscope image of the exfoliated monolayer on the visco-elastic gel film used for exfoliation. Areas appearing in lighter grey are few-layer tungsten diselenide. c, Monolayer sample after transfer to a diamond substrate. The contrast of this image has been enhanced to improve the visibility of the atomically thin WSe2 film. The red arrows mark the same edge in b and c, which has been identified as the zigzag direction using the SHG scan.
