Many new and intriguing phenomena occur in nanometer (10-9 m) scale that are of fundamental scientific interest. However it is difficult to study these phenomena using light, since we cannot focus light to such small dimensions with regular optical lenses due to a limitation imposed by diffraction of light. We study nanoscale properties by overcoming the diffraction limit.
Our research interests include:
- Subwavelength-scale fundamental properties and spatial dynamics of surface plasmon polaritons
- Plasmonic metamaterials
- Near-field nanoscopy of novel correlated transition metal oxides and their interaction with plasmon resonances
- Spectroscopic imaging of organic and inorganic semiconductors in the frequency range visible to THz
- Bionanoparticles and nanobiotechnology
Rapid technological advances driven by the discovery of new physical phenomena have often been closely associated with the development of new materials. Our work is focused on fundamental understanding of metal-insulator transitions (MIT) in novel hybrid transition metal oxides and plasmonic metamaterial structures. This goal will be achieved experimentally by the use of fundamental physical and chemical studies of Metal Insulator Transition (MIT) at nanoscale spatial dimensions. Our research program is also focused on discover of new thermodynamically stable transition MIT with an efficient interface in a hybrid-plasmonic-metamaterial design.
In plane propagation of the strong field associated with surface plasmon polaritons allows effective radiation energy transfer and enhances light absorption in thin film organic photovoltaics influencing the generated photocurrent. We are interested in exploring what the best polymeric material is and optimum thickness of the polymer for best focusing and propagation of surface plasmons in hybrid plasmonic-organic photovoltaics that leads to efficient charge generation.
Fundamental subwavelength-scale investigation of localized and propagating Surface Plasmon Polaritons (SPPs) on metal, metamaterial, semiconductor and low dimensional surfaces from visible to THz spectral range. Our technique Apertureless Near-field Scanning Optical microscopy (ANSOM) with an interferometric detection scheme has a unique capability to map SPP distribution and conduct nanoscale direct spatial mapping of the SPPs wave vector, propagation length and reflectivity with subwavelength resolution in amplitude and phase.
We are developing a capping thickness measurement method utilizing the high resolution capability of s-SNOM on single isolated peptide capped nanoparticles. The attachment of biomolecules modify the dielectric properties of the particles, which is detectable with s-SNOM. In contrast to traditional SPR, s-SNOM is more sensitive and requires very little sample (since sensing is performed at a single particle level and the number of molecules on the surface are much smaller than in a bulk solution). In many cases the biological samples are limited or the concentrations are too low to detect with the conventional SPR method. We also put additional layers of molecules after capturing the biomolecule of interest to enhance the s-SNOM contrast.