题 目：Active Terahertz Metamaterials
报告人：Dr. Hou-Tong Chen (Center for Integrated Nanotechnologies，Los Alamos National Laboratory）
During the past decade electromagnetic metamaterials have realized many exotic physical phenomena that are difficult or impossible to occur using naturally existing materials. It provides novel opportunities for efficiently manipulating terahertz (THz) radiation, which has been extremely difficult in the past due to the lack of materials responding in this frequency range. The resonant response in metamaterials enhances the interaction with THz waves, and makes it possible to realize passive and active functional devices for control and manipulation of THz radiation with unprecedented performance. In this talk, I will show hybrid THz metamaterials capable of actively switchable and frequency tunable resonant response. These active metamaterial structures are realized through the integration of semiconducting materials (silicon and gallium arsenide) and complex metal oxides (high-temperature superconductors and ferroelectric materials) into the resonant elements. The resonance switching and tuning is accomplished through the application of an external stimulus including temperature, photoexcitation, or voltage bias. A few examples will be shown, such as hybrid semiconducting metamaterials serving as THz modulators, frequency tunable high-temperature superconducting metamaterials, and photo-induced handedness switching in chiral meta-molecules. Both experimental and numerical results will be shown with excellent agreement.
Dr. Hou-Tong Chen received his B.S. and M.S. degrees from the University of Science and Technology of China (USTC) in 1997 and 2000, respectively, and PhD degree from Rensselaer Polytechnic Institute (RPI) in 2004, all in physics. Between 2005 and 2008 he was a postdoctoral research associate in Los Alamos National Laboratory (LANL), and currently he is a technical staff member in the Center for Integrated Nanotechnologies (CINT) at LANL, a Department of Energy/Office of Science Nanoscale Science Research Center (NSRC) jointly operated by Los Alamos and Sandia National Laboratories as a national user facility. Hou-Tong’s research has centered in the terahertz science and technology. He is responsible for the first demonstration of a terahertz scanning near-field microscope capable of nanometer resolution. He is also a pioneer in terahertz metamaterials and devices for effective control and manipulation of terahertz radiation. Hou-Tong has published 45 papers in peer-reviewed journals including Nature, Nature Photonics, and Physical Review Letters, which have been highly cited over 1300 times according to ISI Web of Science. He has delivered over 40 invited presentations in international conferences and colloquia and seminars in research institutes. Hou-Tong received LANL Achievement Award and Postdoctoral Publication Prize Honorable Mention, both in 2007. He has been in the organizing committee of several conferences and workshops.