Invited Paper
Interaction of Surface Plasmons and Dye Molecules: Loss Compensation, Stimulated Emission and Strong Coupling

Surface plasmons, whose current and emerging applications range from sensing and medical treatment to photovoltaics and detectors, play an increasingly important role in the modern technology [1]. Even larger number of emerging uses, e.g. signal processing [2] and nanolarers [3], call for active plasmonic systems involving gain, nonlinearity, and tunability.

Many of these functionalities can be accomplished by adding dye molecules to plasmonic systems. Excited dye molecules can provide for optical gain that partially or fully compensates the surface plasmon loss [4]. When the gain exceeds the loss, stimulated emission of surface plasmons occurs [3-5]. Generated coherent surface plasmon oscillations outcouple to photonic modes, constituting miniature lasers, which can be nanoscopic in one, two, or three dimensions. Over last decade, these phenomena have been actively studied by our and other research groups.

What has been nearly overlooked is the fact that at high concentrations of dye molecules, which are required to provide for a substantial gain, strong coupling can occur between surface plasmons and ensembles of highly concentrated dye molecules. These phenomena, studied without relation to stimulated emission and gain, revealed a splitting and avoided crossing in the SPP dispersion curve, in the frequency range corresponding to the absorption band of the dye molecules [6]. We have recently found that implications of strong coupling can extend beyond the interaction of surface plasmons and absorbing dye molecules to include splitting of the dispersion curve due to coupling with spontaneously emitting molecules as well as its possible effect on the Förster energy transfer in vicinity of metallic surfaces [7].

An overview of the state-of-the-art and novel results will be presented at the conference.

[1] S. A. Maier, Plasmonics: Fundamentals and Applications, Springer (2010).

[2] H. Atwater, Scientific American 17, 56 - 63 (2007).

[3] M. A. Noginov, et al., Nature 460, 1110-1112 (2009).

[4] A. Sudarkin, P. Demkovich, Sov Phys Tech Phys. 34, 764-766 (1989).

[5] D. Bergman, M. Stockman, Phys. Rev. Lett. 90, 027402 (2003).

[6] T. K. Hakala, et al., Phys. Rev. Lett., 103, 053602 (2009).

[7] T. Tumkur, et al. Faraday Discussions, FD 178 (2014).

mnoginov@nsu.edu