Polarization-Insensitive Metalenses at Visible Wavelengths.

Khorasaninejad, M; Zhu, A Y; Roques-Carmes, C; Chen, W T; Oh, J; Mishra, I; Devlin, R C; Capasso, F · Nano Lett · 2016

basic_science · Level V

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Abstract

In this Letter, we demonstrate highly efficient, polarization-insensitive planar lenses (metalenses) at red, green, and blue wavelengths (λ = 660, 532, and 405 nm). Metalenses with numerical apertures (NA) of 0.85 and 0.6 and corresponding efficiencies as high as 60% and 90% are achieved. These metalenses are less than 600 nm-thick and can focus incident light down to diffraction-limited spots as small as ∼0.64λ and provide high-resolution imaging. In addition, the focal spots are very symmetric with high Strehl ratios. The single step lithography and compatibility with large-scale fabrication processes make metalenses highly promising for widespread applications in imaging and spectroscopy.