Title: 
Design at the Nanoscale: Reaching the Limits of Light-Matter Interactions

Speaker: 
Owen Miller, Yale University

Abstract:
Nanophotonics is developing at a rapid pace, with ever more materials, form factors, and structural degrees of freedom now available. To confront these large design spaces, and leverage them for transformative technologies, new theoretical tools are needed. Across a range of photonics applications, I will demonstrate that the combination of large-scale computational optimization with new analytical frameworks enables rapid identification of superior designs, and spurs discovery of fundamental limits to wave-matter interactions.

In photovoltaics, the famous ray-optical 4n2 limit to absorption enhancement has for decades served as a critical design goal. I will show that at subwavelength scales, non-intuitive, computationally designed textures outperform random ones, and can closely approach 4n2 enhancements. Pivoting to generic scattering problems, I will show how a convex formulation of passivity constraints leads to general bounds on the strength of any linear light-matter interactions. The bounds provide a figure of merit for evaluating any 2D or 3D material, and suggest pathways to low-loss plasmonic structures. They provide fundamental limits to free-electron radiation and near-field radiative heat transfer, fields with expansive and relatively unexplored design spaces. Finally, we generalize the convex constraints into the complex frequency plane, deriving the first “power-bandwidth” limits for general nanophotonic systems.

Biography:
Owen Miller is an Asst. Prof. of Applied Physics at Yale. He received his EE PhD in 2012 from UC Berkeley, where as an NSF Graduate Fellow he was advised by Eli Yablonovitch, followed by a post-doctoral appointment in MIT Applied Math, working with Steven Johnson. He received bachelor's degrees in EE and physics from the University of Virginia in 2007. His research interests center around leveraging large-scale computational optimization and theoretical analysis for nanophotonic devices. He received a 2016 AFOSR Young Investigator Award.