Spatiotemporal response of chiroptical metallic nanostructure under strong coupling plasmonic modes

The strong coupling of localized surface plasmons can significantly modulate the optical properties of metallic nanostructures and dramatically extend the application area of surface plasmons. However, its influence on the spatiotemporal response of the chiroptical system comprising metallic nanostructures has not yet been revealed. Here, we investigate the spatiotemporal response of a T-shaped Au nanorod dimer under the oblique incidence excitation, which can achieve an enhanced chiral signal induced by the strong coupling of plasmonic modes. For the two hybridized plasmonic modes, the intensities of the chiral signal are 0.46 and -0.39 for the shorter and longer wavelength resonant modes, respectively. Circular dichroism can be enhanced by the difference of plasmonic mode and near field intensity distribution with the excitations of plasmonic resonant modes. The dephasing time of the two hybridized plasmonic fields has been obtained with the excitation of circularly polarized light by time-resolved photoemission electron microscopy. This result can provide deep insight into the interaction between the chiroptical property and plasmonic coupling of metallic nanostructures, effectively optimizing the application of chiral plasmons in biological medicine, analytical chemistry, and physics.