(a) Phase profile when nanoparticle width is sweeped inside one periodicity for a three-block discretized metasurface. Si and SiO₂ are used for making the metasurface. Sketch in the right shows the geometry of the discretized metasurfaces. (b) When the frequency is set at 400 THz, absorption has a similar value as in the case of ideal metasurfaces. Both cases are better than in the case with no metasurface. The right panel shows the scattered E-field profiles, confirming large light trapping.