Dielectric lens guides in-plane propagation of surface plasmon polaritons.

In this work, we present in-plane propagation of surface plasmon polaritons (SPPs) guided by a single dielectric (Al2O3) subwavelength lens. By mounting a designed Al2O3 nanoparticle on the silver film, the effective index of a silver-Al2O3 interface is influenced by the particle thickness, then the phase difference between the silver-air and silver-Al2O3 interface can be utilized to modulate the in-plane propagation of SPPs. We show that an elliptical Al2O3 lens transforms the diffusive SPPs into a collimated beam, whose direction of propagation and beam width can be easily controlled. We also present that a triangular Al2O3 lens significantly reforms the SPPs to a Bessel beam, which possesses non-diffractive and self-healing properties. Our investigation provides unique way to guide the in-plane transport of SPPs by using dielectric subwavelength elements, which may achieve potential applications in plasmonic integrated circuits.

Polarization-dependent strong coupling between surface plasmon polaritons and excitons in an organic-dye-doped nanostructure.

In this work, we demonstrate polarization-dependent strong coupling between surface plasmon polaritons (SPPs) and excitons in the J-aggregates-attached aperture array. It is shown that the excitons strongly couple with the polarization-dependent SPPs, and Rabi splittings are consequently observed. As a result, the polarization-dependent polariton bands are generated in the system. Increasing the incident angle, the polaritons disperse to higher energies under transverse-electric illumination, while the polaritons disperse to lower energies under transverse-magnetic illumination. Therefore, at different polarization incidence, we experimentally achieve distinct polaritons with opposite dispersion directions. In this way, tuning the polarization of the incident light, we can excite different polaritons whose energy propagates to different directions. Furthermore, by retrieving the mixing fractions of the components in these polariton bands, we find that the dispersion properties of the polaritons are inherited from both the SPPs and the excitons. Our investigation may inspire related studies on tunable photon-exciton interactions and achieve some potential applications on active polariton devices.

Multimode photon-exciton coupling in an organic-dye-attached photonic quasicrystal.

In this Letter, we present hybrid strong coupling between multiple photonic modes and excitons in an organic-dye-attached photonic quasicrystal. The excitons effectively interact with the photonic modes offered by the photonic quasicrystal, and multiple hybrid polariton bands are demonstrated in both experiments and calculations. Furthermore, by retrieving the measured dispersion map, we get the mixing fractions of photonic modes and excitons, and show that the polariton bands inherit not only the energy dispersion features, but also the damping behaviors from both the photonic modes and the excitons. Our investigation may inspire related studies on multimode light-matter interactions and achieve some potential applications for multimode sensors.