Planar Lenses at Visible Wavelengths

TL;DR

This paper demonstrates the design and fabrication of high-NA titanium dioxide metasurfaces as planar lenses capable of diffraction-limited imaging at visible wavelengths, offering a compact alternative to traditional bulky lenses.

Contribution

The authors introduce high-aspect-ratio titanium dioxide metasurfaces as high-NA meta-lenses with demonstrated high efficiency and resolution at visible wavelengths, advancing miniaturized optical systems.

Findings

Achieved NA = 0.8 with high efficiency at multiple wavelengths

Demonstrated sub-wavelength resolution and high magnification

Provided imaging quality comparable to commercial objectives

Abstract

Sub-wavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as meta-lenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405 nm, 532 nm, and 660 nm with corresponding efficiencies of 86%, 73%, and 66%. The meta-lenses can resolve nanoscale features separated by sub-wavelength distances and provide magnification as high as 170x with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that meta-lenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.