Infrared polarizer based on direct coupling to surface-plasmon polaritons

TL;DR

This paper introduces a cost-effective, narrowband infrared polarizer leveraging surface-plasmon polaritons, achieving high extinction ratios and efficiency, demonstrated around 10.6 micrometers with nanoporous aluminum oxide.

Contribution

It presents a novel infrared polarizer design based on polarization-dependent coupling to surface-plasmon polaritons, with experimental validation using nanoporous aluminum oxide.

Findings

Extinction ratio up to 1000 for desired polarization

Efficiency of up to 95% at 10.6 micrometers

Stacking can achieve extinction ratios over 10^6

Abstract

We propose a new type of reflective polarizer based on polarization-dependent coupling to surface-plasmon polaritons (SPPs) from free space. This inexpensive polarizer is relatively narrowband but features an extinction ratio of up to 1000 with efficiency of up to 95% for the desired polarization (numbers from a calculation), and thus can be stacked to achieve extinction ratios of 106 or more. As a proof of concept, we experimentally realized a polarizer based on nanoporous aluminum oxide that operates around a wavelength of 10.6 um, corresponding to the output of a CO2 laser, using aluminum anodization, a low-cost electrochemical process.