Engineering Photonic-Plasmonic Devices for Spectroscopy and Sensing Applications
The control of light on the nano-scale has driven the development of novel optical devices such as biosensors, antennas and guiding elements. These applications benefit from the distinctive resonant properties of thin films and nanoparticles consisting of noble metals. Many optimization parameters exist in order to engineer nanoparticle properties for spectroscopy and sensing applications: for example, the choice of metal, the particle morphology, and the array geometry.
By utilizing various designs from simple monomer gratings to more complex engineered arrays, we model, fabricate, and experimentally characterize plasmonic arrays for sensing applications. In this work, I have focused on the novel paradigm of photonic-plasmonic coupling to design, fabricate, and characterize optimized nanosensors. In particular, nanoplasmonic necklaces, which consist of circular loops of closely spaced gold nanoparticles, are designed using 3D FDTD simulations, fabricated with electron-beam lithography, and characterized using dark-field scattering and surface-enhanced Raman spectroscopy of pMA monolayers.
I show that such necklaces are able to support hybridized dipolar scattering resonances and polarization-controlled electromagnetic hot-spots. In addition, necklaces exhibit strong intensity enhancement when the necklace diameter leads to coupling between the broadband plasmonic resonance and the circular resonator structure of the necklace. These necklaces lead to stronger field intensity enhancement than nanoparticle monomers and dimers, which are also carefully studied.