题目： Controlling Light with Optical Metasurface on Demand

报告人：曾铭纶博士

主持人：李向平研究员

时间：2018年5月25日（周五）10:00-11:00

地点：曾宪梓科学馆405会议室

报告摘要：

Metasurfaces are two-dimensional photonic nanostructures composed of subwavelength resonators(called meta-atoms). The optical functionalities of metasurfaces can be tailored by designing the geometrical parameters of the unit cells. They have promised to advance photonics and optoelectronics due to their ultracompact sizes and great capabilities to control and manipulate light . In this talk, I will report my research results on applications of metasurface devices for active light manipulation and color generation. In the first part I will discuss a novel spectroscopy method called coherent control spectroscopy for actively controlling and characterizing the optical resonances of planar metasurface devices. The proposed method is based on the fact that multipole resonances of metasurfaces can be selectively enhanced or suppressed by moving it along a standing wave. By using this method, the absorption of an ultrathin metasurface device can be tuned from nearly perfect absorption to near zero. Hidden high order resonances in multilayered metasurfaces such as magnetic Fano resonance and toroidal dipole resonance can be revealed and enhanced by using the coherent control spectroscopy as well . In the second part of my talk I will discuss the applications of phase-change material Ge2Sb2Te5 for low-loss and tunable metasurface devices. Optical properties of GST can be reversibly tuned by switching its phase states. By utilizing GST nanostructures as the unit cells of the metasurface, the optical properties of the metasurfaces such as resonance wavelength, output reflection angle can be continuously tuned. It will be very useful in the applications of low loss and speedy tunable devices. Finally, I will discuss a novel metasurface device composed of Al nanoparticles that color can be continuously tuned across the visible spectrum. An Al metasurface was fabricated on a highly stretchable and transparent substrate. By stretching the substrate in either of its two dimensions, the period and therefore the scattering color can be tuned across the full visible spectrum. The proposed two-dimensional design of the metasurface enables continuous color tuning while keeping the elastic modulation to a minimum (less than 35%).

报告人简介：

Dr. Ming Lun Tseng is currently a Postdoctoral Research Fellow in Research Center for Applied Sciences, Academia Sinica, Taipei. His research interests are investigating novel nanomaterials for tunable and nonlinear metasurfaces, and delivering metasurfaces for real-world applications. In 2008, Dr. Tseng started his research career in Prof. Din Ping Tsai’s research group at Taiwan University. During his graduate program, Dr. Tseng aimed to innovate plasmonic components and meta-structures for energy and sensing applications. In 2013, he visited Prof. Nikolay I. Zheludev's group at University of Southampton and worked on a research project called “Coherent control of meta-devices. He successfully developed a novel spectroscopy method to actively control the functionalities of planar metasurfaces. In 2014, he completed his PhD degree with the Dean’s award at Taiwan University. In 2016, he joined Dr. Naomi Halas’ research group at Rice University, USA as a postdoctoral researcher. At Rice University, he was working on tunable metasurfaces for color generation and image switching. So far, he has published 24 papers (more than 600 cited times, h-index 13), including Nano Letters, ACS Nano, Advanced Materials, Laser & Photonics Review, etc. He also serves as a reviewer of international journals such as Nano Letters, ACS Nano, Scientific Reports, and Optics Express, etc.

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光子技术研究院

2018年5月21日