| dc.description.abstract | For the past few decades, the development of gap plasmons has been turned from science fiction into reality, and played a pivotal role in the fields of nanocircuitry, terahertz generation, near-field optical microscopy, high-density data storage, high efficiency solar cells, single molecule detection, photo-thermal therapy, and nontoxic bio-labels. This thesis presents in depth full-vectorial analysis for the linear/nonlinear and local/nonlocal properties of coupled surface plasmons in a variety of gap structures, and the application to the detection of single molecule.
In the structure design and analysis, the “plasmonic superprism” was proposed for the analysis of angular dispersion of light waves in free space. It can be readily used for the manufacture of miniaturized spectrometer with a detection sensitivity as high as 5.4˚/nm; The “plasmonic carousel” explored the origin of giant mode splitting from intracavity resonance. This effect wad found useful in simultaneously monitoring the position and the polarizability of nano-objects; the “indefinite cavity” revisits the Goos-Hänchen phase shift in a tiny metallic slit, and the peculiar resonance was applied to design an optical cavity with infinite enhancement factor and nearly zero mode; the “nonlinear Raman enhancement and temperature suppression” unraveled the strong coupling between the temperature field and electromagnetic field in metal nanoparticles. The nonlinear relationship between the temperature and the electromagnetic enhancement as a function of illumination intensity was tailored to give appropriate detection sensitivity for single molecules while avoid thermal degradation.
Experimentally, the study “anomalous blinking characteristic in single molecule surface enhanced Raman spectroscopy” based on home-built Raman microscope clearly observed the gap plasmons assisted single molecule Raman scattering. Of particular interest, the synchronous blinking in various vibrational modes was attributed to the vibronic coupling; the study “optical frequency mixing at gold nanoisland” was conducted basing on home-built multi-color pump-probe system. Four wave mixing dynamics with a temporal resolution <40 fs was relaized which is useful for nonlinear spectroscopy and bio-labeling; “three dimensional optical Talbot carpet” was demonstrated based on scanning near-field optical microscope, where 3D interference pattern beyond the diffraction limit was mapped.
This thesis opens an avenue for studying of the interactions between surface plasmons and nano-objects where the dynamics were probed by spatial-temporal resolved spectroscopy. The results will certainly benefit to the scientic society, particularly in the fields of bio-photonics and next-generation nanosystems. | en_US |