Title:Hyperbolic phonon polaritons in hexagonal boron nitride

时间：2019年1月24日（周四）上午9：30

地点：南开大学泰达应用物理研究院四楼报告厅

报告题目：Hyperbolic phonon polaritons in hexagonal boron nitride

报告人：戴思远（Auburn University，USA）

摘要: Hyperbolic materials where principal components of the permittivity tensor have opposite signs enable a series of advances in nanophotonics and materials engineering including negative refraction, super-resolution imaging and ultrasensitive biomedical sensing. While hyperbolicity was previously achieved with metamaterials by artificial fabrication, we discovered natural hyperbolicity in hexagonal boron nitride (hBN) [Science 343, 1125 (2014)]. The hyperbolicity in phononic hBN is immune to electronic losses as directly revealed in nano-imaging of the hybrid light-matter waves – the polaritons. We further achieved polariton propagation elongation and loss compensation via isotopic enrichment [Nature Materials 17, 134 (2018)] and crystal suspending [Nano Letters (2019)]. The highly-confined and low-loss polaritons allow subdiffractional focusing and imaging via hBN slab with a record high resolution [Nature Communications 6, 6963 (2015)]. By stacking hBN, graphene and phase change materials in the form of heterostructures, we demonstrated the dynamic tuning of hyperbolic response with electrostatic gating [Nature Nanotechnology 10, 682 (2015)] and temperature control [arXiv 1809.09652 (2018)]. In parallel, we accomplished a high degree steering of polaritonic waves [Advanced Materials 19, 1706358 (2018)] as well as internal structure diagnosis in a fashion of polariton tomography [Nano Letters 18, 5205 (2018)].

个人简介: Siyuan Dai is an assistant professor in Mechanical Engineering Department at Auburn University, starting from January 2019. He received his B.S. degree in Applied Physics from University of Science & Technology of China in 2011, and Ph.D. in Physics from University of California, San Diego in 2017. From 2017 to 2018, he was a postdoc fellow in department of electrical and computer engineering at the University of Texas at Austin. Dr. Siyuan Dai has been invited to present and serve as session chairs for MRS and APS. He is the recipient of 2017 Fritz London Postdoc Fellowship, 2017 UCSD Physics Chair’s Challenge award and 2015 Chinese Government award for outstanding self-financed student aboard.His current research focuses on light-matter interactions in emerging materials and nanophotonics.