Optimizing plasmon-enhanced fluorescence with nonlocal metallic nanospheres

Christos Tserkezis, Nikolaos Stefanou, Martijn Wubs, N. Asger Mortensen

Research output: Contribution to conferencePaperResearchpeer-review

Abstract

The fluorescence signal η of molecules coupled to plasmonic nanoparticles (NPs) is optimized through extended simulations, taking the metal nonlocal optical response fully into account. Solid Au and Ag nanospheres, as well as SiO2/Au(Ag) core/shell NPs (of total radius R), are engineered to maximize the ratio of radiative to nonradiative losses and match the emitter emission wavelength, λem. For a molecule modeled as an electric dipole p, oriented parallel to the incident field E, the optimal emitter-NP distance is then identified within the local response approximation (LRA). Introducing nonlocal corrections, the plasmon blueshift predicted by the hydrodynamic Drude model [1] leads to a small reduction of η. If however the plasmonic mode does not coincide exactly with λem, this blueshift can tune the mode to increase η. Nevertheless, when size-dependent losses are also taken into account, through the recent Generalized Nonlocal Optical Response (GNOR) theory, the concurrent contribution of modal shifts and nonradiative losses, together with a reduced emitter excitation rate due to the decreased field intensity, lead always to a strong reduction of fluorescence (see Fig. 1). Finally, we identify situations where the common, intuitive recipe of tuning the NP modes to match λem can in fact lead to strong fluorescence quenching, instead of the anticipated enhancement. Our results highlight the necessity for careful modeling and design of plasmon-field-enhancement based applications.
Original languageEnglish
Publication date2016
Number of pages1
Publication statusPublished - 2016
Event14th International Conference of Near-Field Optics, Nanophotonics and Related Techniques - Hamamatsu, Japan
Duration: 4 Sep 20168 Sep 2016

Conference

Conference14th International Conference of Near-Field Optics, Nanophotonics and Related Techniques
CountryJapan
CityHamamatsu
Period04/09/201608/09/2016

Bibliographical note

Conference paper, NFO-14: The 14th International Conference of Near-Field Optics, Nanophotonics and Related Techniques (http://nfo-14.org/ )

Cite this

Tserkezis, C., Stefanou, N., Wubs, M., & Mortensen, N. A. (2016). Optimizing plasmon-enhanced fluorescence with nonlocal metallic nanospheres. Paper presented at 14th International Conference of Near-Field Optics, Nanophotonics and Related Techniques, Hamamatsu, Japan.