A Metalens with a Near-Unity Numerical Aperture

A Metalens with a Near-Unity Numerical Aperture

Nano Letters

10.1021/acs.nanolett.8b00368

https://doi.org/10.1021/acs.nanolett.8b00368

Ramón Paniagua-Domínguez, Ye Feng Yu, Egor Khaidarov, Sumin Choi, Victor Leong, Reuben M. Bakker, Xinan Liang, Yuan Hsing Fu, Vytautas Valuckas, Leonid A. Krivitsky, Arseniy I. Kuznetsov

27 February 2018

Ramón Paniagua-Domínguez, Ye Feng Yu, Egor Khaidarov, Sumin Choi, Victor Leong, Reuben M. Bakker, Xinan Liang, Yuan Hsing Fu, Vytautas Valuckas, Leonid A. Krivitsky, and Arseniy I. Kuznetsov. (2018). A Metalens with a Near-Unity Numerical Aperture. Nano Letters,18 (3), 2124-2132, DOI: 10.1021/acs.nanolett.8b00368

The numerical aperture (NA) of a lens determines its ability to focus light and its resolving capability. Having a large NA is a very desirable quality for applications requiring small light–matter interaction volumes or large angular collections. Traditionally, a large NA lens based on light refraction requires precision bulk optics that ends up being expensive and is thus also a specialty item. In contrast, metasurfaces allow the lens designer to circumvent those issues producing high-NA lenses in an ultraflat fashion. However, so far, these have been limited to numerical apertures on the same order of magnitude as traditional optical components, with experimentally reported NA values of <0.9. Here we demonstrate, both numerically and experimentally, a new approach that results in a diffraction-limited flat lens with a near-unity numerical aperture (NA > 0.99) and subwavelength thickness (∼λ/3), operating with unpolarized light at 715 nm. To demonstrate its imaging capability, the designed lens is applied in a confocal configuration to map color centers in subdiffractive diamond nanocrystals. This work, based on diffractive elements that can efficiently bend light at angles as large as 82°, represents a step beyond traditional optical elements and existing flat optics, circumventing the efficiency drop associated with the standard, phase mapping approach.

Publisher Copyright

This research / project is supported by the Agency for Science, Technology and Research Science and Engineering Council (SERC) - Pharos Dielectric Nanoantennas
Grant Reference no. : 152 73 00025

This research / project is supported by the National Research Foundation, Singapore - Competitive Research Programme
Grant Reference no. : NRF-CRP14-2014-04

This research is supported by core funding from: Data Storage Institute (DSI)
Grant Reference no. :

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see 10.1021/acs.nanolett.8b00368.

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