2012年11月9日雷党愿博士学术报告
题目（Topic）：Single-particle plasmon-resonance spectroscopy andtransformation optics applications in nanoplasmonics
报告人（Invited Speaker）：Professor Dangyuan Lei,
Department of Applied Physics, the Hong Kong Polytechnic University
主持人（Host）：陈焕君 副教授
时 间（Time）：2012年11月9日上午：10:30～11:30
地 点（Venue）：广东省显示材料与技术重点实验室讲学厅
摘要（Abstract）：Nanoplasmonics is a rapidly emerging sub-discipline of nanophotonics that studies the interaction of light with metal structures at the nanoscale. It uses surface plasmons, which are the light- or electron-beam-induced coherent oscillations of conduction electrons at the interface between metal and dielectric materials. Due to their enhanced optical near-field at a subwavelength scale and the strong geometry- and environment-dependent optical response, surface plasmons have found a host of promising applications in high-sensitivity spectroscopy, waveguiding, imaging and biosensing.
In this talk, I will first give an overview of my previous and current research achievements in this fascinating field and highlight their implications of many important and real applications. I will then focus on two main topics, including plasmon-resonance based spectroscopy and the use of transformation optics to design novel plasmonic nanostructures. Single-particle plasmon resonance spectroscopy is a novel technique that can be used for nanomaterials studies with simultaneous nanoscale spatial resolution and ultrasensitive spectroscopic characterization ability. This technique has been successfully used to reveal the Mott-type phase transition in vanadium dioxide (VO2) thin films and study the role of defects on the phase-transition energy in VO2 nanoparticles. Following this, I will introduce the transformation optics concept and use it to design versatile plasmonic nanocavities with unprecedented properties and great potential of practical applications. For example, a nanocrescent and a pair of kissing nanowires transformed from an infinite metal slab and a metallodielectric cavity, respectively, show a broadband absorption and scattering response and a superfocusing behaviour of electric field in the visible and near infrared range. Interestingly, the broadband response in overlapping cylinders exhibits a lower bound cut-off frequency, which blue-shifts when the overlap distance increases. Once the structure singularity is removed in a nanowire dimer, multiple resonances emerge in the absorption spectrum while some invisibility dips occur in the scattering spectrum and originate from a destructive interference between surface plasmon modes. These devices could allow for the realization of solar-cell concentrators, plasmonic bandgap filters, invisible and non-invasive sensors as well as enhanced substrates for Raman scattering, photoluminescence and fluorescence. At the end of my talk, I will briefly highlight our recent work on plasmon hybridization and decomposition for biochemical sensing and thin-film nanometrology.
Biography
雷党愿，博士，助理教授，于2005年在西北大学获得理学学士学位，随后于2007年在香港中文大学获得哲学硕士学位。在英国政府EPSRC Studentship 和帝国理工学院Deputy Rector’s Award全额奖学金的资助下，雷博士于2008年10月初赴帝国理工学院攻读博士学位，师从世界著名纳米光子学专家Stefan Maier教授，并长期与世界著名超材料研究专家Sir John Pendry教授保持合作关系，随后于2011年获得博士学位。雷博士的博士论文曾获得帝国理工学院颇具声望的“Anne Thorne PhD Thesis Prize”。在帝国理工学院从事11个月的博士后研究之后，雷博士于2012年9月初受聘为香港理工大学应用物理系助理教授，从事纳米光子学的相关研究。雷博士是美国化学学会邀请会员，同时也是英国物理所会员。目前，雷博士的研究方向专注于纳米光子学和转换光学，以及它们在纳米材料研究，光催化和光合成研究，以及光伏器件和生物传感器方面的应用。从2007年开始，雷博士先后在Nature Communications, Nano Letters, ACS Nano 和 Physical Review Letters发表学术论文28篇，这些文章先后被包括Science, Nature Materials, PhysOrg.com and Nanotechweb.org等著名杂志专门评述和“研究亮点”专门报道。