题 目：Dirac Cone Dispersions in Photonic Crystals and Zero Refractive Index
报告人：Dr. Zhi Hong HANG （Department of Physics, Hong Kong University of Science and Technology）
Electronic and photonic systems with Dirac cones in the band structure possess amazing wave transport properties. Materials with a zero refractive index also possess very interesting wave manipulation characteristics. These two seemingly unrelated classes of material are actually related in a subtle way. We show that by employing accidental degeneracy, dielectric photonic crystals can be designed and fabricated which exhibit Dirac cone dispersion at the center of the Brillouin zone at a finite frequency. Many interesting properties intrinsic to a Dirac cone dispersion can be realized. By applying effective medium theory, we relate the same dielectric photonic crystal to a material with effectively zero permittivity and permeability. A zero refractive index metamaterial is one in which waves do not experience any spatial phase change and such peculiar material has many interesting wave manipulating properties. We numerically and experimentally demonstrate in the microwave regime that such dielectric photonic crystals with reasonable dielectric constants do manipulate waves as if they have near zero refractive indices at and near the Dirac point frequency.
Introduction to the Speaker
Dr. HANG Zhihong received his bachelor’s degree in Fudan University. He then went to continue his post-graduation study in HKUST in 2001. He received MPhil degree and PhD degree in physics under the supervision of Prof. C. T. Chan. He is currently a research associate in department of Physics, HKUST and his research interest includes optically induced force and Optical Binding; Metamaterial, Plasmonic Structure and Photonic Crystal and microwave experiments.