University of California, Riverside

Department of Electrical and Computer Engineering



Scalable Manufacturing of Plasmonic and Metasurfaces


Scalable Manufacturing of Plasmonic and Metasurfaces
 
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Scalable Manufacturing of Plasmonic and Metasurfaces

December 8, 2014 - 11:00 am
Winston Chung Hall, 205/206

Abstract

The area of nanoarchitectures for plasmonic and metamaterial applications has uncovered a rich area of physical phenomena with applications including sensing, energy, imaging, and light guiding.  These exciting, emergent properties require a detailed interplay between experimental studies, theoretical design and scalable nanomanufacturing to utilize their potential in technological applications. In order to address these challenges, I have developed versatile methods for self-organization of colloidal nanoparticles (NPs). NPs from colloidal solution have controlled nanomaterial interfaces allowing for tuning of the plasmon resonances as well as mitigating losses and affecting optical properties; NPs effectively serve as meta-molecule building blocks. In addition, colloidal assembly is beneficial as a high-throughput, wafer scale deposition method.  I will present experimental data coupled with theoretical simulations showing arrangements of NPs deposited from colloids serve as plasmonic and metamaterial surfaces.  We have achieved robust surface enhanced Raman scattering (SERS) sensors approaching single molecule detection limits reproducibly over large areas using colloidal assembly.  We will show by varying driving forces for assembly, diffusion versus electrophoresis, NP clusters with gaps between NPs of 4 nm down to 1 nm, respectively, are obtained, shown in Fig. 1. These systems are useful to understand the role of quantum effects in plasmon dynamics and molecular fluctuations in single molecule spectroscopy. Arrays of tightly coupled metal and metal- dielectric NPs also support narrow band resonances, Fano resonances, based on “dark” electric and/or magnetic resonances. We will discuss how material interfaces can be used to mitigate losses that eliminate Fano resonant features.  For example, the extinction and absorption efficiencies resulting from an array of linear trimers of Au nanoshells in homogeneous environment show that efficiency is affected by changing dye concentration in nanoshells.  The use of dyes as gain media induces sharpened Fano resonance features (attributed to the meta-molecule nature of the linear trimers) and increased maximum absorption efficiency at 422 THz.  Using similar methods, circular nanoclusters (CNC) of metal NPs can support a magnetic Fano resonance at 472 THz via dipole moments forming a current loop under oblique TE-polarized plane wave incidence. In particular, array-induced resonances are narrower than single-CNC-induced ones and also provide even larger field enhancements, in particular generating a magnetic field enhancement of about 10-folds and an electric field enhancement of about 40-folds for a representative metasurface. Since natural magnetism fades away at infrared and optical frequencies and artificial magnetism is cumbersome to achieve in these regimes, as conventional split ring resonators are difficult to scale down to optical wavelengths, nanoparticles assembled from colloids are a scalable approach to engineer materials’ electromagnetic properties.

Biography

Prof. Regina Ragan received her B.S. summa cum laude in Material Science and Engineering in 1996 from the University of California, Los Angeles and Ph.D. in Applied Physics in 2002 from the California Institute of Technology. As a PhD student she was awarded as a NSF, Bell Laboratories and Intel Fellow.  From 2002-2004 she was a postdoctoral scholar in the Information & Quantum Systems Laboratory at Hewlett Packard.  Since 2004, she has been a Faculty member in the Department of Chemical Engineering and Materials Science at the University of California, Irvine. She is a recipient of the National Science Foundation Faculty Early CAREER Award.

 

 

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University of California, Riverside
900 University Ave.
Riverside, CA 92521
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Electrical and Computer Engineering
Suite 343 Winston Chung Hall
University of California, Riverside
Riverside, CA 92521-0429

Tel: (951) 827-2484
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