Polarization-independent, achromatic metalenses that operate across a broad window in the near-infrared have been developed and tested by Sajan Shrestha and co-workers from Columbia University and Brookhaven National Laboratory in the USA. The key innovation behind the design of the lenses is the use of suitable meta-units — the building blocks of metasurfaces — to provide diverse phase dispersions. As a proof-of-principle demonstration, a dielectric metasurface platform of amorphous silicon nanostructures on a quartz substrate was employed. Based on the numerical simulation of the phase dispersion for each meta-unit, metalenses composed of the three meta-units, singular pillers, annular pillars and concentric pillars with a height of 1,400 nm, were built. The lenses were experimentally characterized by passing a tunable beam from a supercontinuum laser source through a monochrometer and to the metalens. The three-dimensional intensity distribution around the focal point was then measured by acquiring a stack of two-dimensional images at different distances from the metalens. A focused beam diameter of 200 μm was consistently obtained at a focal distance of 800 μm (numerical aperture of about 0.13) over the wavelength range of 1,200–1,650 nm. The beam diameter was nearly diffraction-limited with no obvious distortion.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Horiuchi, N. Broadband achromatic lens. Nature Photon 13, 72 (2019). https://doi.org/10.1038/s41566-019-0352-3
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41566-019-0352-3