Optical nonlinearity and localization of metallic nano thin film
Date Issued
2004
Date
2004
Author(s)
HO, FU HAN
DOI
zh-TW
Abstract
In this thesis, we studied the interactions of light and metallic nanostructures at the nanometer scale. First, the optical properties of gold continuous film and particulate film were studied. The absorption spectroscopy and Z-scan method are used to characterize the linear and nonlinear absorption properties. The experimental results indicated the different transitions occurred in these gold nanostructures, which were the interband transition in the gold film and the surface plasmon resonance in gold nanoparticles. The theoretical calculations also showed the conditions of surface plasmon for these two structures, which was in a good agreement with the experimental results. Second, silver-oxide nanometric thin film was studied. The changes of the local structures were monitored by both optical microscope and SEM, and the nonlinear absorption properties were measured by using Z-scan and pump-probe systems. We found the decomposition process happening by the optical-thermal interactions, and the silver nanoclusters becomes more in the conditions of higher input powers and then tends to aggregate in the focal spot. This results in the excitation and resonance of localized plasmons by the external optical fields. We also observed the nonlinear scattering, near-field enhanced and localized fields by using both far- and near-field measurements. Third, the bow-tie nano-antenna was theoretically studied for its near-field optical properties. We found the enhanced and localized fields are generated due to the dipole interaction and plasmon excitation. We also could control and optimize the exact location and the magnitude of enhanced fields by the proper design. In summary, we hope these results would show more significant insights of the optical properties and physical mechanism of the metallic nanostructures, which might be applied for the future nanophotonics and plasmonics.
Subjects
奈米光子學
奈米光學
近場光學
表面電漿子
plasmonics
nano-optics
nanophotonics
near-field optics
Type
thesis