1、 Junqiu Liu（刘骏秋）
Chip-scale optical frequency combs using ultralow-loss silicon nitride photonics
基于超低损耗氮化硅集成光学的芯片频率梳技术
ABSRACT
Optical frequency combs are broadband light sources consisting of equidistant grid of frequencies that are precisely know. Over the past decades, optical frequency combs have revolutionized timing, spectroscopy and metrology. A recent breakthrough is the generation of frequency combs in high-Q, nonlinear optical microresonators, which can now be built based on photonic integrated circuit (PIC), thanks to the established semiconductor nano-fabrication technology. This new type of frequency combs, often called as “microcombs”, enables scalable, chip-size, turnkey-operation frequency combs at battery-level power consumption. In addition, the manufacturing of microcombs has now reached a commercialization level for foundry production with high volumes. My talk will cover the fundamental operational principles and latest technological development (particularly the fabrication process) of microcombs using ultralow-loss silicon nitride integrated photonics, as well as a number of key system-level applications demonstrated recently.
光频率梳是由等间隔的单一频率组成的宽带光谱，其每一根梳齿的频率均精确知晓。在过去的二十年里，光频率梳对很多领域起到了决定性的影响，这些领域包括时间/频率精密测量和光谱学。近年来一个重要的频率梳技术进展是在高品质因素、非线性的光学微腔里产生频率梳。如今，伴随着半导体微纳加工技术的发展和成熟，这些特殊的光学微腔已经可以全部由芯片集成光波导来构建。这种新型的光频率梳（又称“微梳”），使实现芯片大小、可拓展、易操作、电池功率驱动的频率梳成为可能。同时，制造这些频率梳芯片可使用大规模半导体微纳加工技术和生产线。我的报告将主要覆盖微梳的工作机理和近期的发展（尤其是微纳加工技术的发展）。其中，超低损耗的氮化硅集成光芯片技术是最重要的基石。同时，我也会介绍下近期数个利用芯片频率梳的重要应用工作。
BIOGRAPHY
Junqiu Liu graduated from the School of Gifted Young, the University of Science and Technology of China (USTC) in 2012, with a BSc in Physics. He obtained his MSc in Photonics from the University of Erlangen-Nuremberg, Germany, in 2016, with the highest distinction (“mit Auszeichnung bestanden”). He received his PhD from EPFL in 2020, under the supervision of Prof. Tobias J. Kippenberg, with his PhD thesis entitled “Silicon Nitride Integrated Nonlinear Photonics”. Currently, he continues his research at EPFL as a postdoc fellow.
Junqiu Liu’s main research interest covers integrated photonics, nonlinear optics, microwave photonics, and MEMS. He has published more than 30 publications, including 3 Nature, 3 Nature Photonics / Physics, 4 Nature Communications, 1 Science Advances, 4 Optica, 2 PRL / PRX etc. He has given more 30 talks in international conferences, including 7 invited talks. He is the recipient of the Best Student Paper awarded by Nature Photonics in the European Conferences on Integrated Photonics (ECIO 2019).
刘骏秋2012年毕业于中国科学技术大学少年班物理专业，获理学学士学位。他2016年获得德国埃尔兰根-纽伦堡大学理学硕士学位，并获最高毕业荣誉。他2020年获得瑞士洛桑联邦理工学院（EPFL）的博士学位，导师是Tobias J. Kippenberg教授，论文课题是研究基于氮化硅芯片集成的非线性光学和光频率梳的物理背景和技术应用。他现在是EPFL的博士后研究员。
刘骏秋的主要研究兴趣覆盖集成光学，非线性光学，微波光子学，和微机电系统等。他已发表超过30篇文章，其中包括Nature三篇，Nature Photonics / Physics三篇，Nature Communications四篇， Science Advances一篇，Optica四篇，PRL/PRX两篇。他在国际会议上作口头报告超过30次，其中大会邀请报告7次，并在2019欧洲集成光学会议（ECIO）上获得全场最佳学生报告（唯一）。
2、Sui Yang（杨隋）
Photonic Soft Metamaterials: From Symmetry Control to Quantum Interaction
光子软超材料：从对称性控制到量子相互作用
ABSRACT
Light-matter interactions have progressively reshaped and promoted our current technologies of our modern society ranging from imaging, information processing and communications to energy aspects. However, these optical functions have been severely limited by the traditional library of materials, design approaches and scalability. Metamaterials are artificially engineered structures to design photonic matters that can shape electromagnetic responses at will. Yet traditional metamaterials are considered as ‘hard’ materials that structural units are typically on a planar geometry and responses cannot be tailored after the formation which severely limit their material properties and applications. In this talk, I will present my recent contributions to explore a new class of ‘soft’ metamaterials that can overcome such limitations, in which building blocks and overall configurations that can be freely tailored, even after formation. In particular, I will first focus on the exploration of self-tailored photonic meta-atoms and lattices by harnessing the complex interplay between thermodynamics and optical symmetry. Moreover, I will discuss how to expand such soft-meta approach to create the long pursuit of Casimir quantum trap (self-trapping without external energy) ever since 1948, arisen from quantum vacuum fluctuations. These results provide new insights that facilitate and expand the light-matter interactions and their applications not attainable in nature.
光与物质相互作用的研究是现代技术从成像、信息处理和通信到能源方面的至关重要的基石。然而，目前这些新颖的光学功能受到了传统材料、设计方法和可扩展性的严重限制。近年来发展的超材料可以突破传统材料的限制，据其电磁响应设计人工的材料结构。然而，这些超材料的结构单位目前通常都基于平面几何体上，在形成后无法进行自响应。 这些"硬"超材料严重限制了其光学特性和应用。在本次会议中，我将介绍我最近的研究，探讨一类新型的"软"超材料，其中构建基块和整体配置，可以自由定制，即使在形成之后其光学功能也可以自发调制。首先，利用热力学和光学对称性之间的复杂相互作用， 我将介绍一种全新的自反馈组装超材料结构， 探索自定制元人工原子和格子对称原理以及其对材料折射率的影响。此外，我将讨论如何扩展这种"软"超材料方法，实现量子涨落的光学器件。自1948年卡西米尔效应提出以来，卡西米尔量子陷阱一直处于理论研究阶段，实验上一直认为其不可能被实现。我们首次通过化学表面被覆技术，创造了一种卡西米尔量子陷阱，可以利用量子真空波动自我捕获纳米粒子。这些研究结果对促进和扩展光物质交互作用，以及现代技术从成像、信息处理和通信到能源方面提供了广阔的应用空间。
BIOGRAPHY
Dr. Sui Yang received his Ph.D. degree from Applied Science and Technology at UC Berkeley in 2015. He will be Assistant Professor of Materials Science & Engineering at Arizona State University and is currently a research scientist at the University of California, Berkeley, where he serves as the research leader at the Nanoscale Science and Engineering Center (NSEC). He has authored and coauthored ~30 papers in many prestigious journals, including Nature, Science, Nature Nanotechnology, Nature Photonics, Nature Communications, JACS and etc. His work received wide media coverage from Nature publications, Science News, Scientific American, Physics World, Phys.Org, R&D Magazine, Photonics World, and various other media sources. In recognition of his multidisciplinary accomplishments, His work led to numerous awards including but not limited to the NKT Photonics Student Award, Reaxys Ph.D. Prize from Elsevier and MINE Young Scientist Award.
杨隋博士于2015年获得加州大学伯克利分校应用科学技术专业的博士学位，将会加入亚利桑那州立大学工程学院担任助理教授，他目前是加州大学伯克利分校纳米科技中心的研究员。杨隋博士曾在众多知名期刊发表论文30余篇，包括自然，科学，自然-纳米技术，自然-光学，自然-通讯和美国化学会志等。他的研究成果也得到各大媒体的广泛关注报道，包括有自然期刊(Nature publications)，科学新闻(Science News)，科学美国(Scientific American)，物理世界(Physics World)，物理机构(Phys.Org)，研发杂志(R&D Magazine), 光学世界(Photonics World) 等。鉴于他在跨学科领域的突出贡献，杨隋博士获得了诸多奖项包括NKT光学学生奖(NKT Photonics Student Award), 爱思唯尔博士奖（Reaxys Ph.D. Prize from Elsevier) and MINE 青年科学家奖(MINE Young Scientist Award)等.
3、Amit Agrawal
Metasurface enabled integrated quantum nanophotonics
运用超表面技术的集成量子纳米光子学
ABSRACT
Over the last decade, flat optical elements composed of an array of deep-subwavelength dielectric or metallic nanostructures of nanoscale thicknesses – referred to as metasurfaces – have revolutionized the field of optics. Because of their ability to impart an arbitrary phase, polarization or amplitude modulation to an optical wavefront as well as perform multiple optical transformations simultaneously on the incoming light, they promise to replace traditional bulk optics in applications requiring compactness, integration and/or multiplexing. Recent demonstrations including atom trapping, full-Stokes polarimetry, quantum-light generation and tomography, LIDAR and imaging/spectroscopy demonstrate the broad range of technologies where metasurfaces have already had a significant impact.
In this talk, we demonstrate the versatility of spatial shaping metasurfaces to be directly integrated on integrated nanophotonic chips for their applications as an efficient interface to AMO systems. This platform provides precise control of optical beam-delivery whilst maintaining integrability and scalability for the specifications required by various AMO technologies. Through spatial multiplexing of metasurfaces integrated with grating out-couplers directly on a nanophotonic chip, we show the ability to create arbitrary optical fields and multifunctional optical response in the far-field to enable applications such as cold atom traps and atomic clocks. Finally, we conclude by discussing the ability of metasurfaces to fully shape the spatiotemporal properties of light at the ultrafast time scale, and on nanometer length scales.
在过去的十年中，由一系列深亚波长纳米级厚度的的电介质或金属纳米结构（称为超表面）组成的平面光学元件彻底改变了光学领域。由于它们具有将任意相位，偏振或幅度调制到光波阵面的能力，并且可以同时对入射光执行多种光学变换，因此它们有望在紧凑，集成和/或多路复用的应用中取代传统的光学器件。最近的进展包括，原子俘获，全斯托克斯偏振仪，量子光源和层析成像，激光雷达和成像/光谱学，等等，证明了超表面已经在十分广泛的技术领域中产生了重大影响。
在本演讲中，我们将会把空间整形的超表面直接集成在集成纳米光子芯片上，作为芯片与AMO系统的高效接口，并展示超表面的多种功能及灵活的特性。该平台可精确控制光束的传输，并能够同时保持各种AMO技术所需规格的可集成性和扩展性。通过直接在纳米光子芯片上集成光栅外耦合器的超表面的空间复用，我们将展示在远场中创建任意光场以及多功能光响应，以实现诸如冷原子阱和原子钟等应用的能力。最后，我们将讨论超表面在纳米级尺度上以超快时间尺度完全塑造光的时空特性的能力。
BIOGRAPHY
Amit Agrawal is the Group Leader of the Ultrafast Nano-optics Lab at NIST in Gaithersburg MD, USA and an Associate Research Scientist at the IREAP of the University of Maryland at College Park. He received his Ph.D. in Electrical Engineering from the University of Utah in 2008, followed by a Postdoc at NIST/UMD. He then joined the faculty of Syracuse University in 2011, as the John E. and Patricia Breyer Professor of Electrical Engineering. He has been back at NIST/UMD since 2014, where his research group is developing novel nanophotonic devices operating from the ultraviolet to the infrared for quantum optics applications including atom trapping, atomic clocks and frequency combs.
Amit Agrawal是美国国家标准技术研究所 (NIST, Gaithersburg MD) 的超快纳米光学实验室（Ultrafast Nano-optics Lab）的小组负责人，也是马里兰大学（University of Maryland at College Park）IREAP的副研究员。2008年，他获得了犹他大学（University of Utah）的电机工程博士学位，之后就读NIST / UMD的博士后。随后，他于2011年加入雪城大学（Syracuse University）任教，担任“John E. and Patricia Breyer”荣誉电子工程学教授。他于2014年回到了NIST / UMD，他的研究小组一直在那里从事新颖的极紫外到红外波段的纳米光子器件的开发，用于量子光学应用，包括原子陷阱，原子钟和频率梳。
4、Yi Yang（杨易）
Exotic electromagnetic scattering: near-field, far-field, and synthetic phenomena
新奇的近场，远场和合成电磁散射
ABSRACT
Scattering of electromagnetic waves is related to the inhomogeneity of a photonic system. I will discuss several recent results on electromagnetic scattering. First, I will present a general framework for nanoscale electromagnetism, demonstrated by far-field scattering measurements. The framework extends the applicability of Maxwell’s equations to the deep nanoscale regime. Second, I will treat free-electron radiation as near-field scattering and derive a general upper limit to their spontaneous emission and energy loss. Such an upper limit identifies a slow-electron-efficient regime of radiation operation and methods for enhancing the emission probability. Finally, I will discuss a synthetic scattering phenomena. Based on optical mode degeneracy, we break time-reversal symmetry in orthogonal bases of Hilbert space to synthesize tunable non-Abelian (non-commutative) gauge fields in real space, which enable us to observe the non-Abelian Aharonov—Bohm effect with optical waves.
介绍一个纳米尺度电磁学的通用框架，该框架通过远场散射测量得到证明。该框架将麦克斯韦方程组的适用性扩展到了深纳米尺度范围。其次，通过将自由电子辐射视为近场散射，可以得出其自发发射和能量损失的一般上限。这样的上限揭示了低速电子的高效辐射条件以及用于提高辐射概率的方法。最后，我将讨论合成散射现象。基于光学模式简并性，我们以不同的方式在希尔伯特空间的不同基底下打破了时间反演对称性，以合成实空间中的可调非阿贝尔规范场，这使我们能够用光波观察到了非阿贝尔阿哈罗诺夫-波姆效应。
BIOGRAPHY
Yi Yang is a graduate of Electrical Engineering at Peking University, BSc & MSc. Since 2014, Yi had been a PhD student in the group of Prof. Marin Soljačić at Massachusetts Institute of Technology (MIT), studying photonics and plasmonics. He has been a postdoc in the same group since 2019 fall.
杨易，北京大学电子工程理学学士和硕士，麻省理工学院Marin Soljačić教授研究组博士，研究纳米光子学。自2019年秋天以来，他在同一小组继续博士后研究。
5、 Giulia Tagliabue
Plasmonics for Solar Fuels: Fundamentals and Devices
用于太阳能燃料的表面等离激元技术：基本原理和装置
ABSRACT
Highly-absorbing, plasmonic-metal nanostructures offer unique opportunities to drive challenging photochemical reactions, such as CO2 reduction. In fact, they combine extreme light absorption properties with the generation of highly energetic “hot” carriers. These can be transferred to either an
adjacent semiconductor (sensitization) or an adsorbed molecule before thermalization, the latter process resulting in an alteration of the chemical reaction pathway. Hence, plasmonic hot carriers turn metallic nanostructures into novel photo(electro)catalysts and can have a dramatic impact on energy applications such as solar-fuel generation. To adequately harness hot carriers, fundamental knowledge of their energy distributions, dynamics and associated lifetimes is necessary. In this talk we will discuss
the construction, optoelectronic and photoelectrochemical characterization of plasmon-driven photocathodes based on a metal/p-type semiconductor heterostructure that operate within the visible regime via hot-hole sensitization. In particular, we will show how plasmonic hot carriers can alter the selectivity of solar-to-fuel energy conversion and we will discuss how the metal band structure and hot carrier properties determine their collection efficiency. Importantly, we will present ultrafast transient
absorption spectroscopy data showing that ultra-fast hot-hole injection across the metal/semiconductor interface has a prominent effect onto the thermalization dynamics of hot-electrons in the metal. Finally, we will show recent results on the scalable engineering of perfect light absorbers that could offer a promising path forward in the engineering of plasmonic photocathodes for solar fuel generation.
高吸收性的表面等离激元金属纳米结构对非常具有挑战性的光化学反应提供了独特的机遇（例如减少CO2）。实际上，它们将极高的光吸收特性与高能“热载流子”的产生结合在了一起。这些热载流子可以在热化之前转移到相邻的半导体（敏化）或吸附的分子上，这其中的后一种过程会导致化学反应途径的改变。因此，表面等离激元热载流子可将金属纳米结构转变为新奇的光（电）催化剂，并可能对诸如太阳能发电等能源应用产生巨大影响。为了充分利用热载流子，有关其能量分布，动力学和相关寿命的基础知识必不可少。在本讲座中，我们将讨论基于金属/ p型半导体异质结结构的表面等离激元驱动的光电阴极的构造，光电特性，以及光电化学特性的表征。通过热空穴的敏化作用，该金属/ p型半导体异质结构能在可见光范围内运行。特别地，我们将展示表面等离激元热载流子可以改变太阳能转化为燃料的选择性，并且我们将讨论金属能带结构和热载流子的特性如何决定其收集效率。重要的是，我们将提供超快速瞬态的光谱吸收数据，并展示跨金属/半导体界面的超快速热空穴注入对金属中热电子的热化动力学具有显著的影响。最后，我们将展示完美吸光剂的可扩展技术的最新研究成果，这可能为太阳能燃料的等离子光阴极的工程设计提供一条有希望的道路。
BIOGRAPHY
Dr. Giulia Tagliabue is an Assistant Professor at the Institute of Mechanical Engineering (IGM) at EPFL where she leads the Laboratory of Nanoscience for Energy Technologies (LNET). From 2015 to 2018 she was a SNSF Postdoctoral Fellow and worked at Caltech and the Joint Center for Artificial Photosynthesis. She also collaborated with JPL-NASA on the Venus mission. Dr. Tagliabue obtained her PhD from ETH Zurich in 2015 and previously she obtained her B.S. and M.S degrees cum laude in Mechanical Engineering from the University of Udine in Italy. Concurrently, she also obtained the diploma from the Scuola Normale Superiore of Udine. Overall, Dr. Tagliabue has authored and coauthored more than 20 publications, including in Nature Materials, Nature Communications, Nano Letters and ACS Nano. She also filed two patents. Dr. Tagliabue received several best-student awards as well as two prestigious postdoctoral fellowships from SNSF. She regular participates to world-class conferences both as an invited speaker and organizer and she is an active reviewer for leading journals
in her field. Dr. Tagliabue is a member of MRS, SPIE and OSA and a committee member of the Optics for Energy Technical Group at OSA.
Giulia Tagliabue博士是EPFL机械工程学院（IGM）的助理教授，她领导着能源技术纳米科学实验室（LNET）。从2015年到2018年，她担任SNSF博士后，并在加州理工学院（Caltech）和人工光合作用联合中心（Joint Center for Artificial Photosynthesis）工作。她还与JPL-NASA合作完成了金星任务。 Tagliabue博士于2015年在苏黎世联邦理工学院（ETH Zurich）获得博士学位，此前她于意大利乌迪内大学（University of Udine in Italy）获得了机械工程专业的学士学位和优秀硕士毕业生学位。同时，她还获得了乌迪内高等师范学校（Scuola Normale Superiore of Udine）的文凭。目前，Tagliabue博士已撰写和合著了20多篇出版物，包括《自然材料》，《自然通讯》，《纳米快报》和《ACS Nano》。此外她还申请了两项专利。 Tagliabue博士获得了SNSF的几个“最佳学生奖”以及两个“荣誉博士后”研究金。她经常以受邀演讲者和组织者的身份参加世界一流的会议，并且是该领域领先期刊的活跃评论员。 Tagliabue博士是MRS，SPIE和OSA的成员，也是OSA能源光学技术小组的委员会成员。