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The optical properties and the local electromagnetic field enhancement of a compound structure with rectangular nanohole arrays in Au-interlayer-Au multilayer films are numerically studied using finite-difference time domain method. We investigated some of structure parameters that influence the optical properties of the compound nanostructure. Adjustment of the length of rectangular nanoholes (L), the polarization direction (θ), the thickness of interlayer (SiO, H), and the materials in the interlayer can change the absorption intensity and the resonance peaks. An interlayer is located between the double Au films (Au-interlayer-Au multilayer films) with the function of confining local electromagnetic field. The simulation of the electromagnetic field distribution shows that the location of the local electromagnetic field enhancement can specify the different resonance patterns. The proposed compound nanostructure will be promising for application in portable nanoplasmonic multisensing and imaging. [ABSTRACT FROM AUTHOR]

We have reported on the synthesis of ordered hexagonal Au nanoparticle (NPs) arrays by anodic alumina oxide templates (AAO)-assisted thermal treatment. This simple process has led to the formation of an ordered hexagonal array of Au NPs on the surface of AAO. SERS properties of the ordered hexagonal Au NPs could be obtained by varying the size of Au NPs. Compared with the Au thin film on AAO, the SERS intensity of rhodamine adsorbed on the ordered hexagonal Au NPs was about 1000 times stronger. And the hexagonal Au NPs array films have had stronger Raman-enhanced signal compared to the disorder Au NPs films. Simulations according to the three-dimensional finite-difference time domain (3D-FDTD) have displayed that these electric field enhancements of the ordered hexagonal Au NPs are strongly dependent on the gap distance. Plasmonic ordered hexagonal Au NPs could provide us new platforms to realize novel optoelectronic devices. [ABSTRACT FROM AUTHOR]