Single-Order Transmission Diffraction Gratings based on Dispersion Engineered All-dielectric Metasurfaces

TL;DR

This paper introduces a novel all-dielectric metasurface-based diffraction grating that achieves high-efficiency wavelength discrimination in the zeroth order by dispersion engineering, offering a compact and effective alternative to traditional gratings.

Contribution

It presents a dispersion engineered all-dielectric metasurface design that enables single-order wavelength discrimination with high efficiency, a significant advancement over conventional diffraction gratings.

Findings

Achieves wavelength discrimination in the zeroth diffraction order.

Uses a dispersion engineered nanostructure to emulate a dispersive prism.

Demonstrates broad bandwidth and high efficiency through simulations.

Abstract

A single-order transmission diffraction grating based on dispersion engineered all-dielectric metasurfaces is proposed and its wavelength discriminating properties have been theoretically described and confirmed using numerical simulations. The metasurface is designed using a 2D array of all-dielectric resonators, which emulates a Huygens source configuration to achieve a perfect match to free-space in broad bandwidth. Using a holey dielectric nanodisk structure as the unit cell, the resonant wavelength is tapered across the metasurface to engineer the wavelength dependent spatial phase gradient, to emulate a dispersive prism. Consequently, different wavelengths are steered towards different directions and thus are discriminated on the output image plane. Due to subwavelength periodicities involved, the wavelength discrimination is achieved directly in the zeroth diffraction order of the device, unlike conventional diffraction gratings, thereby providing a high efficiency wavelength discriminating device.