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

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Owen Miller, Yale University
06 September 2017 from 11:00 AM to 12:00 PM
339 Davey Laboratory
Contact Name
Mikael Rechtsman
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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 4n^2 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 4n^2 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 apply to free-electron radiation, where recent experimental measurements by a collaborator demonstrate Smith-Purcell radiation approaching our bounds. And the passivity approach can be extended to the field of thermal radiation, where it leads to a generalization of the ray-optical concept of a "blackbody" to near-field radiative heat transfer.