Functional nanostructured plasmonic materials: fabrication, simulation, imaging and sensing applications

Abstract

Surface plasmons, due to their extreme sensitivity to changes in refractive index occurring at a metal/dielectric interface and their ability to significantly enhance electromagnetic fields near a metal, offer exciting opportunities for real-time, fully label free forms of chemical/biological detection and field-enhanced applications including surface enhanced Raman scattering (SERS), and photovoltaics. Novel classes of plasmonic crystals fabricated with precisely controlled arrays of subwavelength metal nanostructures provide a promising platform for the sensing and imaging of surface binding events with micrometer spatial resolution over large areas. Soft lithography, one family of unconventional nanofabrication methods, provides a robust, cost-effective route for generating highly uniform, functional nanostructures over large areas with molecular scale resolution. This dissertation describes the development and utility of several classes of functional, nanostructured plasmonic materials with predictable optical properties. A novel, low-cost optical sensor with atomic scale sensitivity at visible wavelength range was developed by tuning the optical response of a plasmonic crystal to visible wavelengths through optimization of the distribution and thickness of the thin metal film. Sensing and imaging of various surface binding events were studied to demonstrate their utility for label-free detection. Finite-Difference Time-Domain (FDTD) calculations were carried out to model the optical response of the system and gain insight into the physics of the system. New classes of plasmonic crystals were developed using new materials and fabrication methods, in concert with rational design of the device form factor guided by both experiment and computational electrodynamics simulations.