Propagating Surface Plasmon Polaritons Excited at the Graphene Oxide/AgAu Alloy Interface Enhance Nonlinearity

Abstract

Graphene oxide (GO) contains intrinsic tunable plasmons, leading to highly attractive plasmonic phenomena, besides the GO coupling with metal nanostructures is promising for plasmonics. Herein, a system consisting of an AgAu alloy entangled in a protein network, AgAu@cages, coupled with a GO layer is designed and analyzed. To overcome the challenges posed by the synthesis of the hybrid GO/metal system, the AgAu alloy is grown inside a proteinaceous network. The approach allows control over the alloy size distribution and a close contact with the samples, with positive impact on the plasmonic analysis. The hybrid system reveals a strong dependence on the incident angle and a shorter linewidth as well as a redshift, motivating further investigations to elucidate the phenomenon. Combined experimental and numerical investigations lead to the displaying of the strong coupling that occurs between the plasmons and the molecular cavity of GO, and a coherent amplification of molecular motion. In conclusion, the versatility of GO‐based systems allows the manufacture of plasmonic and optical devices sensitive to a wide range of frequencies, from terahertz to the visible frequencies, with extremely low driving voltage.