Extinction Behavior and Near-Field Enhancement of 3D Hybrid Nanostructures Consisting of Ag-Coated SiO2 Nanorods

AbstractThe optical property of three-dimensional (3D) hybrid nanostructures consisting of Ag-coated SiO2 nanorods (Ag-SiO2 NRs) is studied by a method of finite-difference time-domain calculations. In the visible-light to infrared band, the extinction spectra of single Ag-SiO2 NRs are basically dominated by three surface plasmon resonance (SPR) peaks. By calculating the electric fields of Ag-SiO2 NRs excited by the incident light in resonance with the three SRP peaks, the plasmons are identified to originate from the electronic oscillation located at the bottom, the side surface, and the top, respectively, different from the extinction behavior of spherical or semispherical Ag-coated SiO2 nanostructures. The extinction behavior of Ag-SiO2 NRs is also found to become obviously different from that of pure Ag NRs when the thickness of Ag layers is less than the penetration depth of incident light in pure silver. The plasmon coupling between the Ag-SiO2 NRs is investigated using the parallel and fork-like configurations. It is found that the parallel configurations exhibit the extinction spectra similar to those of single Ag-SiO2 NRs, while the plasmon coupling enables the local electric fields to be obviously enhanced, especially in the gap regions. For the fork-like configurations, the plasmon coupling between the Ag-SiO2 NRs results in the enhanced electromagnetic radiation normal to the polarization direction of incident light, forming the hybridized plasmons generated by th...
Source: Plasmonics - Category: Biomedical Science Source Type: research