Highly uniform and efficient, broadband meta-beam-splitter/combiner

TL;DR

This paper introduces a broadband, highly uniform, and efficient metasurface beam splitter/combiner that operates across a wide wavelength range, improving upon existing designs in uniformity, bandwidth, and efficiency.

Contribution

It presents a novel design method using modified particle swarm optimization to achieve high uniformity and efficiency in metasurface beam splitters/combiners over a broad spectrum.

Findings

Achieved >97% uniformity across the bandwidth.

Realized >90% diffraction efficiency in the specified wavelength range.

Extended metasurface design capabilities for high-power optical applications.

Abstract

Subwavelength planar structured interfaces, also known as metasurfaces, are ultra-thin optical elements modulating the amplitude, phase, and polarization of incident light using nanostructures called meta-atoms. The optical properties of such metasurfaces can be controlled across wavelengths by selecting geometries and materials of the meta-atoms. Given recent technological developments in optical device miniaturization, components for beam splitting and beam combining are sought for use within these devices as two quintessential components of every optical setup. However, realizing such devices using metasurfaces typically leads to poor uniformity of diffraction orders and narrow-band operation. Using a modified version of particle swarm optimization, we propose and numerically demonstrate a broadband, reciprocal metasurface beam combiner/splitter with uniformity>97% and diffraction efficiency>90% in the continuous band from {\lambda}=1525 nm to {\lambda}=1575 nm. The proposed approach significantly extends the current state of the art of metasurfaces design in terms of uniformity, bandwidth, and efficiency and opens the door for devices requiring high power or near-unit uniformity.