Concave Plasmonic Particles: Broad-Band Geometrical Tunability in the Near Infra-Red

TL;DR

This paper demonstrates that concave plasmonic nanoparticles can be experimentally tuned across a broad near-infrared spectrum due to their unique geometry, enabling flexible control of optical resonances.

Contribution

It introduces the use of concave geometries in plasmonic particles to achieve broad-band tunability of optical resonances in the near-infrared range.

Findings

Concave particles exhibit broad spectral tunability of resonances.

Resonance tuning is achieved even with particles of aspect ratio near unity.

Surface charge distribution interplay enables resonance flexibility.

Abstract

Optical resonances spanning the Near and Short Infra-Red spectral regime were exhibited experimentally by arrays of plasmonic nano-particles with concave cross-section. The concavity of the particle was shown to be the key ingredient for enabling the broad band tunability of the resonance frequency, even for particles with dimensional aspect ratios of order unity. The atypical flexibility of setting the resonance wavelength is shown to stem from a unique interplay of local geometry with surface charge distributions.