Concepedia

Polarization-Insensitive Metalenses at Visible Wavelengths

Mohammadreza Khorasaninejad, Alexander Y. Zhu, Charles Roques‐Carmes, Wei Ting Chen, Jaewon Oh, Ishan Mishra, Robert C. Devlin, Federico Capasso

Nano Letters · 2016 · 760 citations · 47 references

DOI Full text

Open access

TL;DR

The study demonstrates highly efficient, polarization‑insensitive metalenses operating at red, green, and blue wavelengths (660, 532, and 405 nm). They are fabricated using single‑step lithography, allowing large‑scale production and suitability for imaging and spectroscopy. The metalenses reach NAs of 0.85 and 0.6 with efficiencies up to 90 % and 60 %, are thinner than 600 nm, focus light to diffraction‑limited spots (~0.64 λ) with symmetric high‑Strehl‑ratio focal spots, enabling high‑resolution imaging.

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.