Fig. 3: Characteristics of the PB-metalens and the PR-metalens.

Measured focal length of the PB-metalens (a) and the PR-metalens (b) as a function of incident wavelength. c Feature size R of the PB-metalens; the orange line is from SEM. The inset shows the sampled phase distribution from the layout (left) and a schematic diagram of the relationship between R and focal length f (right). d Feature size R of the PR-metalens; the orange line is from SEM. The inset shows the sampled phase distribution from the layout. e Phase distribution of the PB-metalens at 532 nm and 660 nm, and phase difference Δφ. f Phase distribution of the PR-metalens at 532 nm and 660 nm, and phase difference Δφ