Ultra-narrowband polarization insensitive transmission filter using a coupled dielectric metal metasurface

TL;DR

This paper introduces a polarization-insensitive, ultra-narrowband transmission filter based on a coupled dielectric-metal metasurface, optimized for 1540 nm, with potential for integration into imaging devices due to its tunability and fabrication robustness.

Contribution

The paper presents a novel coupled dielectric-metal metasurface filter with high transmittance, narrow bandwidth, and ease of integration, validated by models and multipole analysis.

Findings

Achieves 0.55 transmittance at 1540 nm with 10 nm FWHM

Exhibits a 100 nm stop zone with ~10^-2 transmittance

Demonstrates robustness and tunability for device integration

Abstract

A coupled dielectric-metal metasurface (CDMM) consisting of amorphous silicon (a-$\textit{Si}$) rings and subwavelength holes in $\textit{Au}$ layer separated by a $\textit{SiO}_{2}$ layer is presented. The design parameters of the CDMM is numerically optimized to have a polarization independent peak transmittance of 0.55 at 1540 nm with a Full Width at Half Maximum ($FWHM$) of 10 nm. The filter also has a 100 nm quite zone with $\sim 10^{-2}$ transmittance. A radiating two-oscillator model reveals the fundamental resonances in the filter which interfere to produce the electromagnetically induced transparency (EIT) like effect. Multipole expansion of the currents in the structure validates the fundamental resonances predicted by the two-oscillator model. The presented CDMM filter is robust to artifacts in device fabrication and has performances comparable to a conventional Fabry-P\'{e}rot filter. However, it is easier to be integrated in image sensors as the transmittance peak can be tuned by only changing the periodicity resulting in a planar structure with a fixed height.