Fig. 3: Simulated focal fields of the metalenses.

Results of the FDTD simulations for the focal fields of the downscaled metalenses. Subfigures a–e show the results for the focal field of the metalens without a grating, while subfigures f–j show the results for the focal field of the metalens with a grating. Subfigures a and f show the images of the focal plane as they were simulated; subfigures b and g depict background-corrected versions of these. They were scaled to the actual dimensions of the focal field, and indications of the profiles that were taken were added, which are shown in subfigures c, d, h and i. Finally, subfigures e and j show the profiles along the optical axis, including a regression line to indicate the depth of field.