Harnessing Propagating and Evanescent Waves with Metasurface

Bio:

Dr. Yongmin Liu obtained his Ph.D. from the University of California, Berkeley in 2009. He joined the faculty of Northeastern University in Boston in Fall 2012, and he is currently a full professor in the Department of Mechanical & Industrial Engineering and the Department of Electrical & Computer Engineering. Dr. Liu’s research interests include nano optics, nanoscale materials and engineering, plasmonics, metamaterials, biophotonics, and artificial intelligence. He has authored and co-authored more than 130 journal papers, including Science, Nature, Nature Photonics, Nature Nanotechnology, Advanced Materials, Physical Review Letters, and Nano Letters. Dr. Liu was a recipient of the Søren Buus Outstanding Research Award at Northeastern University (2024), the Faculty Fellow of College of Engineering at Northeastern University (2019), NSF CAREER Award (2017), Office of Naval Research Young Investigator Award (2016), SPIE DCS Rising Researcher Award (2016), 3M Non-Tenured Faculty Award (2016), and Chinese Government Award for Outstanding Students Abroad (2009). He has served as an editorial board member for Nano Convergence, PhotoniX, EPJ Applied Metamaterials, and Scientific Reports. He is a fellow of Optica (formerly OSA) and SPIE.

Abstract:

Metasurfaces, two-dimensional metamaterials, have recently emerged as a vibrant research area in optics and photonics [1-3]. Unlike traditional bulky optical elements, they can precisely control the amplitude, phase, and polarization of light on an ultrathin platform. Their versatility has enabled the development of flat optical devices for applications ranging from imaging and sensing to display technologies and information processing.

In this talk, I will discuss our work on employing metasurfaces to harness both propagating and evanescent waves, which promise efficient, miniaturized and multifunctional meta-devices. First, I will discuss how to break the fundamental limit of polarization multiplexing capacity of metasurfaces by introducing the engineered noise to the precise solution of Jones matrix elements [4]. We experimentally demonstrate up to 11 independent holographic images using a single metasurface illuminated by visible light with different polarizations—the highest capacity reported for polarization multiplexing. Next, I will present designer metasurfaces that can efficiently control the polarization and trajectory of the radiated light by coupling evanescent waves with the inherent electric and magnetic dipoles of the metasurface [5,6]. Finally, I will discuss our recent advances in on-chip metasurfaces that enable switchable focusing/defocusing and multifunctional generation of orbital angular momentum beams [7].

References: [1] N. Yu et al., Science 334, 333 (2011). [2] A.V. Kildishev et al., Science 339, 1232009 (2013). [3] W. T. Chen et al., Nature Reviews Materials 5, 604 (2020). [4] B. Xiong et al., Science 379, 294 (2023). [5] Z. J. Wang et al., Physical Review Letters 117, 157401 (2016). [6] L. Li et al., Laser & Photonics Reviews 14 , 1900244 (2020). [7] L. Deng et al., Nano Letters 24, 9042 (2024).