Aluminum plasmonics: Fabrication and characterization of broadly tunable plasmonic surfaces for plasmon molecule strong-coupling and fluorescence enhancement

Abstract

Our work based on previous studies [1, 2] confirms, that simple aluminum nanostructures can be utilized as effective plasmonic resonators over a broad range of frequencies and wavelengths. The nanostructured surfaces, fabricated by electron-beam lithography demonstrated relatively narrow-band resonances and are suitable for various plasmonic applications ranging from metal enhanced fluorescence to strong-coupling [1–5] experiments. We represent data for molecule-plasmon coupling near the strong coupling limit and demonstrate that these aluminum structures do act as fluorescence increasing substrates. In this work, we used two different types of dyes. We studied the narrow band j-aggregate forming TDBC with almost no Stokes-shift and a recently developed large Stokes-shift dye commercially available under the name ATTO 490LS. Anti-crossing behavior was observed for both dyes, but a clear Rabi split for the ATTO 490LS was not fully reached. We observed a Rabi split of more than 160 meV for the TDBC sample (Fig. 1) and enhanced selectively the fluorescence of the ATTO 490LS dye more than 3.5 times.