Figure 4. Numerical modelling of scattering from random-phase GSP-based metasurfaces.

(a) Calculated (histogram) and theoretical (red line) PDF of the far-field intensity (when neglecting specular reflection) from an array of 200 × 200 unit cells for excitation by x-polarised incident light when the four types of nanobricks, defined by the intersection of contour lines in Fig. 3b for L_x = L_y, appear with equal probability in the array. The inset shows the associated Fourier image of the far-field intensity within the NA = 0.9. The image is oversaturated in order to visualise the diffusion of light. (b) Similar calculation as in a, but the frequency of occurrence of the four nanobricks is scaled by the inverse of their reflection amplitudes. (c,d) Effective reflectivity (i.e., limited by the NA) as a function of wavelength and NA for the metasurfaces described in (a,b) respectively.