PhD Defense: "Structuring Light to Manipulate Multipolar Resonances for Metamaterial Applications"

Tanya Das

June 1st (Thursday), 4:00pm
Harold Frank Hall (HFH), Rm 4164 (ECE Conf. Rm.)

Multipolar electromagnetic phenomena in sub-wavelength resonators are at the heart of metamaterial science and technology. Typically, researchers engineer multipolar light-matter interactions by modifying the size, shape, and composition of the resonators. Here, we instead engineer multipolar interactions by modifying properties of the incident radiation. In this talk, I propose a new framework for determining the scattering response of resonators based on properties the local excitation field, and apply this framework to expose a number of interesting modifications of the multipolar response of dielectric particles.

First, we derive an analytical theory to determine the scattering response of spherical nanoparticles under any type of illumination. Using this theory, we demonstrate the ability to drastically manipulate the scattering properties of a spherical nanoparticle by varying the illumination and demonstrate excitation of a longitudinal quadrupole mode that cannot be accessed with conventional illumination. Next, we investigate the response of dielectric dimer structures illuminated by cylindrical vector beams. Using finite-difference time-domain simulations, we demonstrate significant modification of the scattering spectra of dimer antennas and reveal how the illumination condition gives rise to these spectra through manipulation of electric and magnetic mode hybridization. Finally, we present a simple and efficient numerical simulation based on local field principles for extracting the multipolar response of any resonator under illumination by structured light. This work enhances the understanding of fundamental light-matter interactions in metamaterials and lays the foundation for researchers to identify, quantify, and manipulate multipolar light-matter interactions through optical beam engineering.

About Tanya Das:

photo of tanya das Tanya Das is a Ph.D. candidate in the ECE department at UCSB. She received her B.S. in Electrical Engineering from the University of Michigan in 2011 and her M.S. from UCSB in 2013. She joined the research group of Professor Jon Schuller in 2013, where she has been working to investigate new methods for manipulating multipolar phenomena in sub-wavelength particles using structured illumination beams.

Hosted by: Professor Jon Schuller