Figure 21.

(a) 16 silicon dioxide blocks (eight elementary cells) placed on metallic substrate (orange). The metasurface has the following parameters: unit-cell dimensions of $D_x=1634$nm and $D_y=698$nm, dimensions of “large” dielectric blocks $d_{x1}=704$nm, $d_{y1}=568$nm, dimensions of “small” dielectric blocks $d_{y1}=704$nm, $d_{y2}=284$nm, height of the blocks $h_1=h_2=148$nm [16]; (b) electric field distribution $|E/E_0|$ when the incident light is normal to the metasurface at the frequency ${\omega }_1=11.4\times {10}^3{\mathrm{cm}}^{-1}=1.41\mathrm{eV}$ (from [17]).