Subwavelength metal grating metamaterial for polarization selective optical antireflection coating

TL;DR

This paper presents a subwavelength metal grating metamaterial that acts as an effective polarization-selective antireflection coating in the infrared, achieving high transmittance and reflection suppression on germanium substrates.

Contribution

It introduces a novel metal/air-gap grating design that simplifies fabrication while providing efficient, polarization-sensitive optical antireflection in the infrared.

Findings

Achieves 93.4% maximal transmittance in mid-infrared range.

Complete reflection elimination for specific polarization.

Does not require deep subwavelength grating periods.

Abstract

A metamaterial structure consisting of a one-dimensional metal/air-gap subwavelength grating is investigated for optical antireflection coating on germanium substrate in the infrared regime. For incident light polarized perpendicularly to the grating lines, the metamaterial exhibits effective dielectric property and Fabry-Perot like plasmon-coupled optical resonance results in complete elimination of reflection and enhancement of transmission. It is found that the subwavelength grating metamaterial antireflection structure does not require a deep subwavelength grating period, which is advantageous for device fabrication. Maximal transmittance of 93.4% with complete elimination of reflection is seen in the mid-wave infrared range.