Fig. 2: θ-dependent THG responses in tBLG.
From: Enhanced third-harmonic generation by manipulating the twist angle of bilayer graphene
a Schematic of our lab-made reflection-type measurement system for nonlinear optical responses in tBLG. b Spectra of nonlinear optical signals from MLG and tBLG over visible wavelengths. The dominant spectra show the typical THG signals centred at 520 nm. Inset: output power dependence of THG signals on pump power. The slopes are near 3, indicating intrinsic THG characteristics. These data were measured at the MLG (black circle) and tBLG (grey and green circle) positions in (c). c THG image of the graphene region in Fig. 1b, scanned by motorized XY stages with a 0.3 μm step resolution over 30 μm × 30 μm. d Histogram of the THG intensity ratio for 63 tBLG regions and MLG. e Tendency of the THG intensity arranged with respect to the 2D/G peak ratio
