CHARACTERIZATION OF FLUORESCENCE FROM QUANTUM DOTS ON NANOSTRUCTURED METAL SURFACES

Abstract

The behavior of fluorescent materials coupled to surface plasmon supporting surfaces and structures is an area of active research due to their fluorescence enhancing properties. The inherent field enhancements present near structures and interfaces where surface plasmons are excited provide great potential for increasing the response of many optical interactions. While many studies focus on the application of plasmonic nanoparticles or finite metallic structures the use of dielectric structures on a continuous metallic film has received little attention. A comprehensive experimental study using dielectric gratings on gold films is presented illustrating the fundamental properties of fluorescence enhancement on such structures. A process for fabrication of samples using Electron Beam Lithography is demonstrated and comparisons between various quantum dot deposition methods are made to determine the best conditions for surface coating. Conditions for optimization of the fluorescence enhancement phenomena for practical application are explored for gratings with square function profile illustrating the influence of gratings on fluorescence behavior and identifying conditions for optimal enhancement. Complementing these results, an understanding of the underlying physical phenomena is developed by differentiation between enhanced emission and enhanced absorption effects using measurements of fluorescence decay lifetime and emission spectra. Using these observations a thorough description of these systems and the requirements for their practical application is illustrated.