Fig. 5. Metaoptic for polarization-insensitive phase and amplitude modulation.

a Schematic of the Si nanodisk that serves as the unit cell for the bottom layer. The disks have a height of h₁ = 440 nm and are arranged in a square lattice with a period of P = 600 nm. b Simulated transmission amplitude $∣t_1∣$ and phase $\angle t_1$ as functions of the disk radius. c Schematic of the nanopost that serves as the unit cell for the second layer. The nanoposts have a height of h_2 = 750 nm. d Simulated transmission amplitude $∣t_2∣$ and phase $\angle t_2$ as functions of the post radius. e Schematic of the bilayer metasurface. The bottom layer is used for amplitude modulation ($∣t∣$), and the top layer is used for phase modulation $\left(\angle t_2\right)$. The total phase profile of the bilayer metasurface is $\angle t_1+\angle t_2.$ f, g, h Designed phase pattern f, along with an optical microscope image g and an SEM image h of the top metasurface. i The designed amplitude profile. j, k Optical j and SEM k images of the bottom metasurface. All phases and amplitudes are calculated for λ = 1400 nm