Mapping the Electromagnetic Near Field of Gold Nanoparticles in Poly(methyl) Methacrylate

Abstract

As electronic and optical devices shrink to the nanoscale, accurate methods for characterizing electromagnetic fields generated by sub-wavelength structures become increasingly important. Absorption in poly(methyl methacrylate) (PMMA) via 4th harmonic generation in metallic nanostructures is a way to characterize complex resonance modes. When exposed with a femptosecond Ti:sapphire oscillator, the damaged PMMA surrounding the nanoparticles can be imaged with an scanning electron microscope, creating an electric near-field intensity profile. This occurs without absorbing the fundamental frequency, and provides an accurate visualization of the resonant fields. Localized surface plasmonic near-fields generated by metallic nanorods have been mapped previously with this technique. In this document, nanorods and bowtie antennas are fabricated and the electric near-field intensity imaged with PMMA mapping. We then analyzed this data to determine more about the technique and about what drives the resonance of plasmonic nanoantennas.