Cathodoluminescence spectroscopy of plasmonic patch antennas: towards lower order and higher energies

TL;DR

This study uses cathodoluminescence spectroscopy to analyze plasmonic patch antennas made of Au, Al, and Au/Al, demonstrating control over their mode operation and spectral range, including access to fundamental modes and blue-shifted operation.

Contribution

It introduces a method to access monomode operation of plasmonic antennas down to the fundamental dipolar mode and demonstrates spectral tuning towards the blue range using aluminum.

Findings

Access to monomode operation down to fundamental dipolar mode

Spectral shift towards blue range with aluminum

Qualitative agreement with semi-analytical mode model

Abstract

We report on the cathodoluminescence characterization of Au, Al and a Au/Al bimetal circular plasmonic patch antennas, with disk diameter ranging from 150 to 900 nm. It allows us access to monomode operation of the antennas down to the fundamental dipolar mode, in contrast to previous studies on similar systems. Moreover we show that we can can shift the operation range of the antennas towards the blue spectral range by using Al. Our experimental results are compared to a semi-analytical model that provides qualitative insight on the mode structure sustained by the antennas.