Abstract:
Nanostructured metals have provided us with a unique opportunity to manipulate light in an unconventional manner. Collectively, subwavelength metallic structures serve as building blocks for optical metamaterials with properties that were not observed or even speculated about in the past. This is a very exciting frontier in optics and materials science, with the promising goal of yielding better solar cells, faster computer chips, ultrasensitive biochemical detectors, and even invisible devices. In this talk I will start with a general description of plasmonic metamaterials, include demonstrations of magnetic, negative-index, and chiral metamaterials in both the linear and the nonlinear regimes, along with their applications for signal generation, biochemical sensing, and optical modulation. The second half of the talk will discuss how to accelerate and automate the design of plasmonic metamaterials via artificial intelligence. The design of photonic structures, conventionally, relies on one’s expertise to guide a progression of electromagnetic simulations that iteratively solve Maxwell’s equations until an optimized solution can be attained. We can circumvent this conventional procedure by means of a deep learning architecture, based on a generative adversarial network and an evolutionary strategy. When fed an input set of customer-defined optical spectra, the constructed generative network generates candidate patterns that match the on-demand spectra with high fidelity. This approach reveals a grand opportunity to expedite the discovery and design of photonic structures for tailored optical responses in a systematic, inverse-design manner.

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Biography:
Wenshan Cai is an Associate Professor (tenured) in Electrical and Computer Engineering at the Georgia Institute of Technology, with a joint appointment in Materials Science and Engineering. Prior to joining Georgia Tech in 2012, he was a postdoctoral fellow at Stanford University. Dr. Cai received his B.S. and M.S. degrees from Tsinghua University in 2000 and 2002, respectively, and his Ph.D. from Purdue University in 2008. His research is in the area of nanophotonic materials and devices, in which he has made a major impact on the evolving field of plasmonics and metamaterials. Dr. Cai has published more than 50 journal papers in prestigious journals such as Science, Nature Materials, Nature Photonics, Nature Nanotechnology, etc., and the total citations of his recent papers have reached more than 10,000 within the past 10 years. He authored the book, Optical Metamaterials: Fundamentals and Applications, which is used as a textbook or a major reference around the world. Dr. Cai is the recipient of several national and international distinctions, including the OSA/SPIE Joseph W. Goodman Book Writing Award (2014), the CooperVision Science & Technology Award (2016), and the Office of Naval Research Young Investigator Award (2017).