Abstract：

Dynamic functionalities in hybrid electronic–photonic systems are being widely pursued to further improve system-level performance in sensing, optical communication, and data processing. Adaptive nanophotonics, featuring a smaller size, faster performance, and better energy efficiency, have drawn tremendous attention in recent years due to their potential integration with smart technology. This talk will focus on advances made by strain engineering of two-dimensional semiconductors and metamaterials driven by phase-transition materials. Strain engineering of 2D gallium selenide has recently revealed exciting nanophotonic effects such as localized bandgap tuning, exciton funneling, and the creation of site-specific single photon emitters. We investigate the reversible local strain engineering of suspended gallium selenide flakes using a novel micromechanical spring with nanoscale probes to induce symmetry-controlled localized strain. The presented research establishes a new platform for streamlining the quantitative understanding of material properties as a function of complex local strain in two-dimensional materials. A THz metamaterial engineered with microelectromechanical systems actuated via the phase-transition characteristics of vanadium dioxide will also be introduced. Through computational modeling and experimental investigation, our THz polarization modulator achieves a broad operation spectrum, high modulation depth, ease of fabrication, ease of operation condition, and continuous modulation capabilities.

Bio：

Dr. Xi Wang is currently an assistant professor in the Department of Materials Science and Engineering at the University of Delaware. Dr. Xi Wang received his Ph.D. in Electrical Engineering from the State University of New York at Buffalo in 2014 and a B.S. degree in Microelectronics from Tsinghua University in 2007. Dr. Xi Wang was a postdoctoral scholar at the University of California, Berkeley, before he started his appointment at UD in 2018. Dr. Xi Wang’s research focuses on the area of nanophotonics, nanomaterials, and tunable nanophotonic devices.