English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

One of the important advantages of optical metasurfaces over conventionaldiffractive optical elements is their capability to efficiently deflect lightby large angles. However, metasurfaces are conventionally designed usingapproaches that are optimal for small deflection angles and their performancefor designing high numerical aperture devices is not well quantified. Here weintroduce and apply a technique for the estimation of the efficiency of highnumerical aperture metasurfaces. The technique is based on a particularcoherent averaging of diffraction coefficients of periodic blazed gratings andcan be used to compare the performance of different metasurface designs inimplementing high numerical aperture devices. Unlike optimization-based methodsthat rely on full-wave simulations and are only practicable in designing smallmetasurfaces, the gradient averaging technique allows for the design ofarbitrarily large metasurfaces. Using this technique, we identify anunconventional metasurface design and experimentally demonstrate a metalenswith a numerical aperture of 0.78 and a measured focusing efficiency of 77%.The grating averaging is a versatile technique applicable to many types ofgradient metasurfaces, thus enabling highly efficient metasurface componentsand systems.

Increasing efficiency of high numerical aperture metasurfaces using the grating averaging technique