Intrinsic Optical Properties and Enhanced Plasmonic Response of Epitaxial Silver

TL;DR

This paper reveals the intrinsic optical properties of epitaxial silver, demonstrating significantly reduced loss and enhanced plasmonic response, which could greatly advance the development of low-loss plasmonic devices.

Contribution

It provides new optical constants for epitaxial silver with lower loss, establishing a benchmark for its fundamental plasmonic properties.

Findings

Reduced optical loss in epitaxial silver

Enhanced surface plasmon polariton propagation distance

New benchmark for silver's optical properties

Abstract

Plasmonics offers an enticing platform to manipulate light at the subwavelength scale. Currently, loss represents the most serious challenge impeding its progress and broad impact towards practical technology. In this regard, silver (Ag) is by far the preferred plasmonic material at optical frequencies, having the lowest loss among all metals in this frequency range. However, large discrepancies exist among widely quoted values of optical loss in Ag due to variations in sample preparation procedures that produce uncontrollable grain boundaries and defects associated with additional loss. A natural question arises: what are the intrinsic fundamental optical properties of Ag and its ultimate possibilities in the field of plasmonics? Using atomically-smooth epitaxial Ag films, we extracted new optical constants that reflect significantly reduced loss and measured greatly enhanced propagation distance of surface plasmon polaritons (SPPs) beyond what was previously considered possible. By establishing a new benchmark in the ultimate optical properties of Ag, these results will have a broad impact for metamaterials and plasmonic applications.