Plasmonic metasurfaces with 42.3% transmission efficiency in the visible

Jihua Zhang,Mohamed Elkabbash,Chunlei Guo,Billy Lam,Subhash C Singh,Ran Wei

doi:10.1038/s41377-019-0164-8

Abstract

Metasurfaces are two-dimensional nanoantenna arrays that can control the propagation of light at will. In particular, plasmonic metasurfaces feature ultrathin thicknesses, ease of fabrication, field confinement beyond the diffraction limit, superior nonlinear properties, and ultrafast performances. However, the technological relevance of plasmonic metasurfaces operating in the transmission mode at optical frequencies is questionable due to their limited efficiency. The state-of-the-art efficiency of geometric plasmonic metasurfaces at visible and near-infrared frequencies, for example, is ≤10%. Here, we report a multipole-interference-based transmission-type geometric plasmonic metasurface with a polarization conversion efficiency that reaches 42.3% at 744 nm, over 400% increase over the state of the art. The efficiency is augmented by breaking the scattering symmetry due to simultaneously approaching the generalized Kerker condition for two orthogonal polarizations. In addition, the design of the metasurface proposed in this study introduces an air gap between the antennas and the surrounding media that confines the field within the gap, which mitigates the crosstalk between meta-atoms and minimizes metallic absorption. The proposed metasurface is broadband, versatile, easy to fabricate, and highly tolerant to fabrication errors. We highlight the technological relevance of our plasmonic metasurface by demonstrating a transmission-type beam deflector and hologram with record efficiencies.

Highlights

Plasmonic metasurfaces (PMs) are two-dimensional arrays of metallic nanoantennas with subwavelength thicknesses and spacings and a spatially varying phase response[1,2]
PMs have an ultrathin thickness on the order of tens of nanometers, are easy to fabricate, support a field confinement beyond the diffraction limit, and have potential to respond on the timescale of a few femtoseconds[21]; these properties are unparalleled in tra
A significant increase in the transmission efficiency of plasmonic geometric metasurfaces (GMs) is facilitated by tuning the multipole response of individual meta-atoms and by minimizing the crosstalk between meta-atoms

Summary

Introduction

Plasmonic metasurfaces (PMs) are two-dimensional arrays of metallic nanoantennas (meta-atoms) with subwavelength thicknesses and spacings and a spatially varying phase response[1,2]. PMs have an ultrathin thickness on the order of tens of nanometers, are easy to fabricate, support a field confinement beyond the diffraction limit, and have potential to respond on the timescale of a few femtoseconds[21]; these properties are unparalleled in tra-. Controlling optical transmission is of interest for many applications, the operation efficiency of ultrathin transmission-type GMs is severely limited. The notion that the metasurface efficiency can be increased by increasing the packing density of meta-atoms cannot be readily extended to GMs. At higher packing densities with smaller meta-atom interspaces, the near field of adjacent meta-atoms starts to couple and modifies the amplitude/ phase responses of individual meta-atoms to deviate from their designed values. The demonstrated efficiencies for transmission-type plasmonic GMs in the visible and near-infrared regions are ≤10% for realizing various functions[37,38,39,40]. Realizing efficient PMs in the visible and near-infrared range, is of paramount technological importance[41]

Methods

Results

Conclusion