Fig. 4: Real-space imaging of polariton canalization in a hBN metasurface.

a Topography of the sample. b–d Experimental near-field distribution of antenna-launched elliptical polaritons on the metasurface at three different frequencies. White dashed lines mark the boundary of the metasurface. e Simulated near-field distribution of the antenna-launched canalization EPhPs on the metasurface. f, g, h Topography and experimental near-field images (at two different frequencies) for the case of an antenna located on an unpatterned area of the same hBN flake. i Blue line shows the near-field profile taken from the image shown in the panel (b) along the vertical dashed blue line, which can be fitted by an exponential decay (dashed red line). Gray line shows the near-field profile taken from g along the vertical dashed gray line. Green line shows the near-field profile taken from h along the vertical dashed green line. j Horizontal near-field line profiles taken from b, g, and h along the horizontal dashed lines, respectively.