Porosity Effect on Surface Plasmon Resonance from Metallic Sculptured Thin Films

TL;DR

This study investigates how porosity in metallic sculptured thin films affects surface plasmon resonance, showing that increased porosity broadens and eventually diminishes the SPR dip, with residual features observed.

Contribution

It demonstrates experimentally and numerically that porosity significantly influences SPR behavior in metallic sculptured thin films, a novel insight for plasmonic applications.

Findings

Increased porosity widens the SPR dip.

High porosity can eliminate the SPR dip.

Residual spectral features remain at high porosity.

Abstract

When a sculptured thin film (STF), made of a metal and $\leq50$ nm thick, is used in lieu of a dense layer of metal in the Kretschmann configuration, experimental data for an STF comprising parallel tilted nanowires shows that a surface plasmon resonance (SPR) can still be excited. As the porosity of the chosen STF increases, experimental data and numerical simulations indicate the SPR dip with respect to the angle of incidence of the exciting plane wave widens and eventually disappears, leaving behind a a vestigial peak near the onset to the total-internal-reflection regime.