High-aspect ratio plasmonic nanostructures

We study plasmonic modes in high aspect ratio nanostructures in the visible wavelength region and explore their performance for sensing applications. Ordered and well-defined plasmonic structures with various cross-sectional profiles and heights can be obtained using a top-down fabrication process that has been developed in our lab. Such plasmonic nanostructures allows improvement of the biosensing performance or enables fabrication of quasi-3D metamaterials. For example gold nanorods and split-ring resonators with heights of up to 1000 nm and feature sizes down to 20 nm were obtained.

Surface-Enhanced Raman Spectroscopy

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Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for enhancing the inherently low Raman scattering cross-sections of molecules, enabling detection down to single molecules. The major mechanism of the SERS effect arises from electromagnetic field enhancement in the vicinity of metallic nanostructures when they are excited at their surface plasmon resonance.

Our aim is to increase the enhancement factors of the SERS technique by developing novel designs and fabrication methods as well as using different excitation wavelengths ranging from UV to NIR. The objective of the project is to design, fabricate and analyze optical properties of metallic nanostructures and to perform Raman spectroscopy experiments of biomolecules. In particular, our current focus is deep-UV surface-enhanced resonance Raman scattering on aluminum nanostructures. We have recently demonstrated that this technique is a highly useful analytical technique for ultrasensitive and label-free detection of biomolecules in real time.