New plasmonic coupling mechanism in longitudinally shifted nanorod heterodimers

Mohammed Alsawafta

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Finite-difference time-domain (FDTD) electromagnetic simulation tool has been employed to calculate both the optical properties and the associated plasmonic coupling features in a compositionally asymmetric nanorod dimer as a function of both gap spacing (g) and longitudinal offset (h). The two interacting nanorods are made of Ag and Au, arranged in a side-to-side configuration (H-aggregate), and illuminated by a longitudinally polarized light. When the two nanorods are shifted away from each other longitudinally, the band position of the longitudinal mode excited in the Ag rod exhibits both red and blueshift due to the varied strength in the inhomogeneous coupling between the discrete excitation of the Ag plasmonic mode and the continuum transition of the Au material. Meanwhile, the corresponding resonance wavelength of the counterpart resonator is blueshifted with increasing the value of the offset. The resonance energy of the Ag shows almost no dependency on the gap spacing detected from no significant change in its resonance frequency with increasing g. For the plasmonic mode excited in the Au rod, the resonance wavelength is blue shifted with g and it follows the trend of a second-order exponential decay function. For both rods, the nearfield intensity reaches its maximum when h approaches the rod’s length due to the significant increase in the surface charge density. The Au-field intensity shows very weak sensitivity to g meanwhile the corresponding intensity of the Ag mode exhibits non-uniform dependency on g.

Original languageEnglish
Pages (from-to)19405-19419
Number of pages15
JournalJournal of Materials Science
Volume57
Issue number41
DOIs
StatePublished - Nov 2022

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