Extended Data Fig. 6: Momentum-space origin of HHG in the TSS.
From: Tunable non-integer high-harmonic generation in a topological insulator
a, Calculated HH spectra, IHH, (black curve) for two test charges placed at the wave vector ky = ±0.001 Å−1 (kx = 0), as obtained from a semiclassical solution of the equations of motion (νTHz = 25 THz, ETHz = 0.1 MV cm−1). b, HH intensity (colour scale) of order n = 15 (see arrow and red dotted area in a) as a function of the starting point (kx, ky) of the test charges in momentum space.
