Infrared Metaplasmonics

TL;DR

This paper introduces metaplasmonics, a new plasmonic modality using nanoribbons that extends the operational wavelength range into the infrared, achieving high confinement and quality factors beyond traditional plasmonic materials.

Contribution

The authors develop and demonstrate a novel metaplasmonic approach with nanoribbons, enabling infrared plasmonics with enhanced confinement and reduced wavelengths, surpassing limitations of ultra-thin metal films.

Findings

Achieved 35x plasmon wavelength reduction.

Demonstrated broad wavelength range with high quality factors.

Numerical simulations suggest up to 150x wavelength reduction is possible.

Abstract

Plasmonic response in metals, defined as the ability to support subwavelength confinement of surface plasmon modes, is typically limited to a narrow frequency range below the metals' plasma frequency. This places severe limitations on the operational wavelengths of plasmonic materials and devices. However, when the volume of a metal film is massively decreased, highly confined quasi-two-dimensional surface plasmon modes can be supported out to wavelengths well beyond the plasma wavelength. While this has, thus far, been achieved using ultra-thin (nm-scale) metals, such films are quite difficult to realize, and suffer from even higher losses than bulk plasmonic films. To extend the plasmonic response to the infrared, here we introduce the concept of metaplasmonics, representing a novel plasmonic modality with a host of appealing properties. By fabricating and characterizing a series of metaplasmonic nanoribbons, we demonstrate large confinement, high quality factors, and large near-field enhancements across a broad wavelength range, extending well beyond the limited bandwidth of traditional plasmonic materials. We demonstrate $35\times$ plasmon wavelength reduction, and our numerical simulations suggest that further wavelength reduction, up to a factor of 150, is achievable using our approach. The demonstration of the metaplasmonics paradigm offers a promising path to fill the near- and mid-infrared technological gap for high quality plasmonic materials, and provides a new material system to study the effects of extreme plasmonic confinement for applications in nonlinear and quantum plasmonics.