EE Colloquium: Metasurfaces: From Flat Optics to Subwavelength Integrated Photonics

Abstract: The optical metasurface – an artificially engineered ultrathin nanostructure – provides us a revolutionary way to tailor the behavior of electromagnetic waves in desired ways. It enables the redesign of optical components into thin, planar, multifunctional elements, promising a major reduction in footprint and system complexity as well as the introduction of new optical functions. In my talk, I will focus on some of our developments on metasurfaces which lead to several novel optical devices like inversely designed achromatic lenses, invisibility skin cloaks, image/beam transformers. In addition to controlling free-space propagating light, I will also introduce our recent developments on a new type of metasurface that is directly incorporated on photonic integrated components and provides flexible control of the guided light. It bridges the free-space optics and the integrated photonics, enabling many novel photonic integrated devices with complex optical functions that have not been possible using conventional approaches, such as off-chip beam steering, fully on-chip integrated spectrometers, waveguide-fed lenses, and photonic integrated orbital angular momentum (OAM) micro-lasers. Our study represents a huge step towards complete control of optical modes on the various optical platforms, and paves exciting new ways for building multifunctional lightweight optical devices for applications such as spectroscopy, free-space optical communications, optical imaging and ranging, and biomedical sensing.

Biography: Dr. Xingjie Ni is the Assistant Professor of Electrical Engineering at the Pennsylvania State University since 2015. He is also a faculty member of the Materials Research Institute at Penn State. Prior to that, he was a postdoctoral fellow at University of California, Berkeley. He received his BS degree in Engineering Physics in 2005 and his MS degree in Automation in 2007 from Tsinghua University, Beijing, China. He completed his Ph.D. degree in Electrical and Computer Engineering at Purdue University in 2012. His research interests are in nanophotonic materials and devices, which encompass metamaterials, integrated photonics, photonic sensors, imaging, and quantum optics. Dr. Ni is one of the five inaugural Moore Inventor Fellows. He received NASA Early Career Faculty Award in 2017. He also got Sony Faculty Innovation Award in 2018, 3M Non-Tenured Faculty Award in 2019, and NSF CAREER Award in 2021.