Fig. 3. Characterisations of the fabricated disordered metasurface Meat-IV.

a Low magnification SEM image of the disordered Ag metasurface. b Two-dimensional Fourier power spectrum of the position of the Ag nanostructures, which is calculated from the SEM image of disordered Ag metasurface. c The tilted view of the disordered metasurfaces with high magnification. Inset is image of a single Ag nanostructure. d A schematic illustration of the light extraction measurement setup. e Size distribution histogram of the Ag nanoparticles in the optimised disordered metasurface and corresponding Log-Normal fitting (black solid line). f Transmission spectrum from the hemispherical glass prisms with Meta-IV for θ_i = 50^o. The SiO₂ substrate covered with disordered Ag metasurface and the prism were bonded together by using index-matching fluid (n = 1.46). Inset: optical image of the spot of transmitted light extracted from the glass prism with disordered Ag metasurface