研究目的
To understand the excitation of a collective surface plasmon resonance (SPR) mode and a gap plasmon mode as well as their dependence on the spacer thickness, nanoparticles spacing and their size in a plasmonic metasurface made of a monolayer of gold nanoparticles in close proximity to an aluminum thin film.
研究成果
The study demonstrates that the optical response of plasmonic metasurfaces can be effectively tuned by adjusting the spacer layer thickness, nanoparticle spacing, and size. The excitation of collective SPR and gap plasmon modes and their dependence on these parameters were confirmed through FDTD simulations and experimental measurements. These findings can be used to design tunable optical metamaterials for various applications.
研究不足
The study is limited to the visible wavelength range and specific configurations of gold nanoparticles and aluminum thin films. The accuracy of the FDTD simulations is limited by the spatial resolution of the spacer layer and the spherical nanoparticles.
1：Experimental Design and Method Selection:
The study employs finite-difference-time-domain (FDTD) calculations to simulate the optical properties of the plasmonic metasurface. The HASP code, a nonstandard variation of the Yee algorithm, is used for its accuracy in simulating metallic nanosurfaces.
2：Sample Selection and Data Sources:
The system under study consists of a monolayer of spherical gold nanoparticles (Au NPs) of given diameter and spacing deposited on a glass substrate, separated by a dielectric (shellac, n = 1.5) spacer layer varying from 7.5 to 35 nm, capped by a 5 nm Al film.
3：5) spacer layer varying from 5 to 35 nm, capped by a 5 nm Al film.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Gold nanoparticles, aluminum thin film, shellac spacer layer, glass substrate. The simulations use a spatial mesh of 2.5 nm spacing and a time step of 0.005 fs.
4：5 nm spacing and a time step of 005 fs.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The FDTD simulations are carried out with periodic boundary conditions in the lateral directions and perfectly-matched-layer (PML) boundary conditions at the top and bottom of the computational box to eliminate artificial reflections.
5：Data Analysis Methods:
The extinction spectra are analyzed to determine the dependence of the SPR and gap plasmon modes on the spacer thickness, nanoparticle spacing, and size.
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