Mid-infrared directional surface waves on a high aspect ratio nano-trench platform

TL;DR

This paper demonstrates a high aspect ratio nano-trench platform supporting broadband, highly localized, and directional mid-infrared surface waves, advancing nanoscale light manipulation techniques.

Contribution

It introduces a novel high aspect ratio nano-trench structure supporting both surface and volume infrared waves with unique properties.

Findings

Supports broadband infrared surface waves from 4 to 14 μm

Exhibits high localization and directionality of surface waves

Enables effective control of mid-infrared light

Abstract

Optical surface waves, highly localized modes bound to the surface of media, enable manipulation of light at nanoscale, thus impacting a wide range of areas in nanoscience. By applying metamaterials, artificially designed optical materials, as contacting media at the interface, we can significantly ameliorate surface wave propagation and even generate new types of waves. Here, we demonstrate that high aspect ratio (1:20) grating structures with plasmonic lamellas in deep nanoscale trenches function as a versatile platform supporting both surface and volume infrared waves. The surface waves exhibit a unique combination of properties, such as directionality, broadband existence (from 4 {\mu}m to at least 14 {\mu}m and beyond) and high localization, making them an attractive tool for effective control of light in an extended range of infrared frequencies.