Fig. 3: Radiation characteristics of the HOT point-defect modes.

a Far-field radiation patterns (top row) and polarization textures (middle row) of the 0D HOT defect mode in metasurfaces based on shrunken (left) and expanded (right) hexamers obtained in 3D full-wave simulations. The far-field intensity distributions host a singularity at the normal direction, feature three lobes in directivity and chiral spirals in polarization, in agreement with the vector field maps theoretically reconstructed using the continuum Dirac model (a, bottom row). b Momentum-space experimental images for the shrunken-lattice case taken with a polarization of excitation beam falling oriented at 0° (top) and 45° (middle), and the superimposed image (bottom) as taken for unpolarized light excitation. The white dashed-line circle corresponds to the 10° angular distribution of emitted light. Black lines depict the experimentally reconstructed distribution of the state of polarization.