Extended Data Fig. 8: NILES for three different optical near-field decay lengths.

a-c The same semi-classical simulation of electron spectra for three tip radii, with fixed enhanced peak intensities as in Fig. 3. As before NILES only shows up for the case of inhomogeneous optical near fields. Additionally, we observe that the optical near fields lead to a reduction of the highest energies of the plateau electrons and at which CEP they appear, indicated by the arrows and solid lines. Once more, we stress the excellent agreement of the numerical results in (c) and the experimental data in Fig. 1, also for the plateau electrons. As before in Fig. 3, the position of the relevant electric cycle is indicated in (d) for different CEPs.