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. While metamaterials are commonly viewed as artificially-structured media capable of realizing exotic electromagnetic properties, we can drive beyond this limited vision and explore the use of optical metamaterials as a generalizable platform for optoelectronic information technology. In this talk I will start with a general description of metamaterials in the conventional linear regime, include experimental demonstrations of the first magnetic metamaterial across the entire visible spectrum, and the world’s first negative-index material at optical frequencies. In the second half of the talk I will steer towards nonlinear light-matter interactions in optical metamaterials, including the electrically induced harmonic generation and optical rectification of light in a perfect metamaterial absorber, the nonlinear spectroscopy and imaging of a chiral metamaterial, and the backward phase-matching in an optical metamaterial where the fundamental and frequency-doubled waves possess opposite indices of refraction.

Biography
Wenshan Cai is an Associate Professor 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 in the Geballe Laboratory for Advanced Materials 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 scientific 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 ~40 journal papers in highly prestigious journals such as Science, Nature Materials, Nature Photonics, Nature Nanotechnology, Nature Communications, etc., and the total citations of his papers have reached over 6,000 within the past few years. He serves as a reviewer or an editorial board member for over 20 scientific journals. In addition, Dr. Cai is the lead author of the book Optical Metamaterials: Fundamentals and Applications, a text used at many universities around the world, for which he won the 2014 Joseph W. Goodman Book Writing Award from OSA and SPIE.