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We have studied dispersion of surface plasmon polaritons (SPPs) in the Kretschmann geometry (prism/Ag/dye-doped polymer) in weak, intermediate, and ultra-strong exciton–plasmon coupling regimes. The dispersion curves obtained in the reflection experiment were in good agreement with the simple model predictions at small concentrations of dye (Rhodamine 590, Rh590) in the polymer (Poly(methyl methacrylate), PMMA). At the same time, highly unusual multi-segment “staircase-like” dispersion curves were observed at extra-large dye concentrations, also in agreement with the simple theoretical model predicting large, small, and negative group velocities featured by different polariton branches. In a separate experiment, we measured angular dependent emission of Rh590 dye and obtained the dispersion curves consisting of two branches, one nearly resembling the SPP dispersion found in reflection and the second one almost horizontal. The results of our study pave the road to unparalleled fundamental science and future applications of weak and strong light—matter interactions.
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This content will become publicly available on January 9, 2026
Energy Transfer for Leaky Surface Plasmon Polaritons in Gold Nanostripes
The properties of the leaky surface plasmon polariton (SPP) modes in gold nanostripes were investigated using scattered light microscopy. Both bare gold nanostripes and stripes coated with a thin polymer film containing a near-infrared absorbing dye were examined. Real-space microscopy images were employed to determine the SPP propagation length, while Fourier space images provided measurements of the wavevector. Frequency versus wavevector dispersion curves were generated by performing experiments at different excitation wavelengths, and the slopes of these curves yielded the SPP group velocities. For the bare nanostripes the group velocity was determined to be vg = (0.92 ± 0.05)c0 and for the dye-coated nanostripes it was vg = (0.85 ± 0.06)c0, where c0 is the speed of light. The SPP lifetimes were estimated by combining the group velocity and propagation length measurements. The results show that the lifetime of the gold SPPs is significantly reduced when the nanostripes are coated with the dye. At the peak of the dye absorption curve the change in the SPP dephasing rate induced by the dye–polymer film was found to be 0.07 fs–1. Finite element simulations show that the increased dephasing is due to a combination of energy transfer from the SPP modes to the dye, as well as increased radiation damping due to changes in the dielectric environment of the nanostructures. These findings provide insights into the energy transfer processes in plasmonic systems, which can be leveraged to optimize the design of plasmonic devices for applications in sensing, imaging and nanophotonic circuits.
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- Award ID(s):
- 2304905
- PAR ID:
- 10570235
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry C
- Volume:
- 129
- Issue:
- 1
- ISSN:
- 1932-7447
- Page Range / eLocation ID:
- 535 to 541
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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