Plasmonic Resonant Properties of Silver Hemispherical Nano-Shell Structures in 2D arrays

• Main Authors: Chih-ShanChang, 張志山
• Other Authors: Shih-Hui Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/93223034136125095241

碩士 === 國立成功大學 === 光電科學與工程學系 === 102 === Localized surface plasmon resonance (LSPR), observed in metal nanoparticle arrays interacting with an incident light field, is an emerging research area for surface-enhanced -Raman-scattering (SERS) biomedical sensing applications. The plasmonic properties of metal nanoparticles can be easily tuned by varying the shape, size and arrangement along with the dielectric environment. Particles with coreshell structure provide an extra degree of freedom to tune the LSPR wavelength. The array structure adds an extra tuning capability by setting the periodicity near the single particle LSPR wavelength to squeeze out a sharp Fano resonant peak. In nano fabrication, semi shell array has advantage over the spherical shell array by the top-down approach. Here, we investigate the LSPR cross section and mode distributions for nano-shell and semi-shell with core radius of 100 nm and shell thickness of 20nm for single and periodic structure using FDTD simulation. Higher order quadrapole modes with bonding and anti-bonding types were observed. Furthermore, we discussed Fano resonance effect on each LSPR modes by adjusting the interparticle spacing. The coupling between the dipole/quadrapole LSPR and the grating mode leads to different resonant properties. The charge distributions of dipole and quadrapole under the influence of Fano resonance are also discussed.