Fig. 3: Spectral map of the near-field distribution.
a Experimentally measured profiles of the near-field amplitude (left) and phase (right) in the Fourier crystal at different excitation frequencies. Every near-field scan is taken across the area of 4 × 2 μm2, followed by integration to obtain a linear profile, which is then normalized. b Numerically calculated near-field amplitude (left) and phase (right) over the Fourier crystal with the period P = 485 nm and the surface modulation depth 70 nm; x = 0 corresponds to the maximal gap between the hBN and gold surface. Black dashed lines are guides for the eye indicating the corresponding near-field features and showing a blue shift of the calculated data (also highlighted by the red dashed line). c Numerically calculated band diagram of the HPhP modes in the Fourier crystal along the direction of surface corrugation. Dashed and dot-dashed lines indicate a correspondence between the near-field and photonic bands.
