Surface plasmon polaritons (SPPs) are bound modes of electromagnetic fields coupled to oscillating charges which can be excited at the interface between a metal and a dielectric. Their sub-wavelength confinement and strong dependence on the surface properties provide a way for focusing and guiding light at the nanoscale, enabling to develop new nano-optical devices. Recently, several works studied the interaction of SPPs with excitonic species and formation of hybrid exciton-SPPs modes (X-SPPs) [1]. These quasiparticles have new and exciting physical properties. For example, unlike photons, these hybrid light-matter modes can scatter through polariton-polariton and polariton-exciton interactions. In addition, the excitons populations can be manipulated to act as a mechanism for ultrafast all optical switches [2]. To use X-SPPs properties for the development of compact devices it is of key interest to study their local properties and efficient ways to transfer energy locally into or out of these modes.

In this talk we will present our recent experimental study of local coupling of light from free space to strongly coupled X-SPPs modes on metal-organic semiconductor interfaces by using a single metallic nanoantenna [3]. The studied sample consisted of a sub-wavelength gold nanowire on top of a thin silver film which is covered with a 30 nm thick layer of J-aggregating dyes in polyvinyl alcohol. We show that the nanowire acts as an antenna that resonantly scatters light to X-SPPs states with a Rabi splitting of 0.1 eV. The locally excited X-SPPs properties were studied by angle resolved spectroscopy of the far-field leaky photons and were compared to the large-scale response through Kretschmann reflection measurements, theoretical calculations and finite-difference time-domain numerical simulations. 

[1]        J. Bellessa, C. Bonnand, J. Plenet, and J. Mugnier, Phys. Rev. Lett. 93, 036404 (2004).

[2]        P. Vasa, W. Wang, R. Pomraenke, M. Lammers, M. Maiuri, C. Manzoni, G. Cerullo, and C. Lienau, Nature Photon. 7, 128-132 (2013).

[3]        E. Eizner, and T. Ellenbogen. Appl. Phys. Lett. 104, 223301 (2014).