In this recently published work, we show that, by engineering the dispersion of each constituent nanostructure, a metalens can possess two different focal lengths with customized focal length shifts. The focal length shift can be designed with achromatic, refractive, or diffractive behavior. Our method is based on a more general design strategy by considering phase and group delay profiles for potential applications in imaging, spectroscopy, and wearable optical devices.

For more information, visit https://aip.scitation.org/doi/10.1063/10.0001351.