Spatial coherence properties of organic molecules coupled to plasmonic surface lattice resonances in the weak and strong coupling regimes.
We study spatial coherence properties of a system composed of periodic silver nanoparticle arrays covered with a fluorescent organic molecule (DiD) film. The evolution of spatial coherence of this composite structure from the weak to the strong coupling regime is investigated by systematically varying the coupling strength between the localized DiD excitons and the collective, delocalized modes of the nanoparticle array known as surface lattice resonances. A gradual evolution of coherence from the weak to the strong coupling regime is observed, with the strong coupling features clearly visible in interference fringes. A high degree of spatial coherence is demonstrated in the strong coupling regime, even when the mode is very excitonlike (80%), in contrast to the purely localized nature of molecular excitons. We show that coherence appears in proportion to the weight of the plasmonic component of the mode throughout the weak-to-strong coupling crossover, providing evidence for the hybrid nature of the normal modes.
COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
L
L
Shi
COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
T K
TK
Hakala
COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
H T
HT
Rekola
COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
J-P
JP
Martikainen
COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland and Department of Imaging Physics, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, NL-2628 CJ, Delft, The Netherlands.
R J
RJ
Moerland
COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
P
P
Törmä