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Metamaterials for radiative sky cooling

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National Science Review 2018年第2期5卷 132-133页

作者： shanhui fan Aaswath Raman Ginzton Laboratory Department of Electrical Engineering Stanford University Department of Electrical and Systems Engineering University of Pennsylvania

From fundamental thermodynamic considerations,in order to convert heat to usable work,it is important to have a heat source with a temperature that is as high as possible,and to have a heat sink with a temperature that is as low as *** vast majority of energy conversion processes at the moment use our ambient surroundings on Earth itself,with a

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Thermodynamic limits for simultaneous energy harvesting from the hot sun and cold outer space

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Light(Science & Applications) 2020年第1期9卷 1373-1383页

作者： Wei Li Siddharth Buddhiraju shanhui fan Department of Electrical Engineering Ginzton LaboratoryStanford UniversityStanfordCA 94305USA

The sun and outer space are two of the most important fundamental thermodynamic resources for renewable energy harvesting.A significant amount of work has focused on understanding the fundamental limit of energy harvesting from the *** recently,there have been several theoretical analyses of the fundamental limit of energy harvesting from outer ***,far less is understood about the fundamental limits of simultaneous energy harvesting from both the sun and outer ***,we consider and introduce various schemes that are capable of simultaneous energy harvesting and elucidate the fundamental thermodynamic limits of these *** show that the theoretical limits can far exceed the previously established limit associated with utilizing only one thermodynamic *** results highlight the significant potential of simultaneous energy harvesting and indicate new fundamental opportunities for improving the efficiency of energy harvesting systems.

关键词： outer harvesting simultaneous

Multi-dimensional band structure spectroscopy in the synthetic frequency dimension

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Light(Science & Applications) 2023年第7期12卷 1425-1433页

作者： Dali Cheng Eran Lustig Kai Wang shanhui fan Ginzton Laboratory and Department of Electrical Engineering Stanford UniversityStanfordCA94305USA Department of Physics McGll UniversityMontrealQC H3A 2T8Canada

The concept of synthetic dimensions in photonics provides a versatile platform in exploring multi-dimensional *** of these physics are characterized by band structures in more than one *** efforts on band structure measurements in the photonic synthetic frequency dimension however are limited to either onedimensional Brillouin zones or one-dimensional subsets of multi-dimensional Billouin *** we theoretically propose and experimentally demonstrate a method to fully measure multi-dimensional band structures in the synthetic frequency *** use a single photonic resonator under dynamical modulation to create a multidimensional synthetic frequency *** show that the band structure of such a lattice over the entire multidimensional Brillouin zone can be measured by introducing a gauge potential into the lattice *** this method,we perform experimental measurements of two-dimensional band structures of a Hermitian and a non-Hermitian *** measurements reveal some of the general properties of point-gap topology of the non-Hermitian Hamiltonian in more than one *** results demonstrate experimental capabilities to fully characterize high-dimensional physical phenomena in the photonic synthetic frequency dimension.

关键词： resonator synthetic dimensional

Structured 3D linear space–time light bullets by nonlocal nanophotonics

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Light(Science & Applications) 2021年第9期10卷 1687-1701页

作者： Cheng Guo Meng Xiao Meir Orenstein shanhui fan Department of Applied Physics Stanford UniversityStanfordCA94305USA Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and Technology Wuhan UniversityWuhan430072China Andrew&Erna Viterbi Department of Electrical Engineering Technion–Israel Institute of TechnologyHaifa32000Israel Ginzton Laboratory and Department of Electrical Engineering Stanford UniversityStanfordCA94305USA

We propose the generation of 3D linear light bullets propagating in free space using a single passive nonlocal optical *** nonlocal nanophotonics can generate space–time coupling without any need for bulky pulse-shaping and spatial modulation *** approach provides simultaneous control of various properties of the light bullets,including the external properties such as the group velocity and the propagation distance,and internal degrees of freedom such as the spin angular momentum and the orbital angular momentum.

关键词： surface angular nonlocal

Measuring,processing,and generating partially coherent light with self-configuring optics

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Light(Science & Applications) 2024年第11期13卷 2726-2733页

作者： Charles Roques-Carmes shanhui fan David A.B.Miller 1E.L.Ginzton Laboratory Stanford University348 Via PuebloStanfordCA 94305USA

Optical phenomena always display some degree of partial coherence between their respective degrees of *** coherence is of particular interest in multimodal systems,where classical and quantum correlations between spatial,polarization,and spectral degrees of freedom can lead to fascinating phenomena(e.g.,entanglement)and be leveraged for advanced imaging and sensing modalities(e.g.,in hyperspectral,polarization,and ghost imaging).Here,we present a universal method to analyze,process,and generate spatially partially coherent light in multimode systems by using self-configuring optical *** method relies on cascaded self-configuring layers whose average power outputs are sequentially *** optimized,the network separates the input light into its mutually incoherent components,which is formally equivalent to a diagonalization of the input density *** illustrate our method with numerical simulations of Mach-Zehnder interferometer arrays and show how this method can be used to perform partially coherent environmental light sensing,generation of multimode partially coherent light with arbitrary coherency matrices,and unscrambling of quantum optical *** provide guidelines for the experimental realization of this method,including the influence of losses,paving the way for self-configuring photonic devices that can automatically learn optimal modal representations of partially coherent light fields.

关键词： coherent modal generating

Metamaterial band theory:fundamentals & applications

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Science China(Information Sciences) 2013年第12期56卷 18-31页

作者： RAMAN Aaswath Pattabhi SHIN Wonseok fan shanhui Ginzton Laboratory Stanford University Stanford

Remarkable progress has been made over the past decade in controlling light propagation and absorption in compact devices using nanophotonic structures and *** sensing and modulation,to on-chip communication and light trapping for solar cells,new device applications and opportunities motivate the need for a rigorous understanding of the modal properties of metamaterials over a broad range of *** this review,we provide an overview of a metamaterial band theory we have developed that rigorously models the behavior of metamaterials made of dispersive materials such as *** theory extends traditional photonic band theory for periodic dielectric structures by coupling the mechanical motion of electrons in the metal directly to Maxwell’s *** solution for the band structures of metamaterials is then reduced to a standard matrix eigenvalue problem that nevertheless fully takes into account the dispersive properties of the constituent *** an application of the metamaterial band theory,we show that one can develop a perturbation formalism based on this theory to physically explain and predict the efect of dielectric refractive index modulation or metallic plasma frequency variation in ***,the metamaterial band theory also provides an intuitive physical picture of the source of modal material loss,as well as a rigorous upper bound on the modal material loss rate of any plasmonic,metamaterial *** in turn places fundamental limits on the broadband operation of such devices for applications such as photodetection and absorption.

关键词： metamaterials photonic band theory plasmonics sensing active metamaterials

Higher-order topological insulators in synthetic dimensions

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Light(Science & Applications) 2020年第1期9卷 831-839页

作者： Avik Dutt Momchil Minkov Ian A.D.Williamson shanhui fan Ginzton Laboratory and Department of Electrical Engineering Stanford UniversityStanfordCA 94305USA

Conventional topological insulators support boundary states with dimension one lower than that of the bulk system that hosts them,and these states are topologically protected due to quantized bulk dipole ***,higherorder topological insulators have been proposed as a way of realizing topological states with dimensions two or more lower than that of the bulk due to the quantization of bulk quadrupole or octupole ***,all these proposals as well as experimental realizations have been restricted to real-space ***,we construct photonic higher-order topological insulators(PHOTIs)in synthetic *** show the emergence of a quadrupole PHOTI supporting topologically protected corner modes in an array of modulated photonic molecules with a synthetic frequency dimension,where each photonic molecule comprises two coupled *** changing the phase difference of the modulation between adjacent coupled photonic molecules,we predict a dynamical topological phase transition in the ***,we show that the concept of synthetic dimensions can be exploited to realize even higher-order multipole moments such as a fourth-order hexadecapole(16-pole)insulator supporting 0D corner modes in a 4D hypercubic synthetic lattice that cannot be realized in real-space lattices.

关键词： topological dimensions insulator

Angle-selective perfect absorption with two-dimensional materials

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Light(Science & Applications) 2015年第1期4卷 59-64页

作者： Linxiao Zhu Fengyuan Liu Hongtao Lin Juejun Hu Zongfu Yu Xinran Wang shanhui fan Department of Applied Physics Stanford UniversityStanfordCA 94305USA National Laboratory of Solid State Microstructures School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China Department of Materials Science and Engineering Massachusetts Institute of TechnologyMA 02139USA Department of Electrical and Computer Engineering University of Wisconsin-MadisonMadisonWI 53706USA Department of Electrical Engineering Ginzton LaboratoryStanford UniversityStanfordCA 94305USA

Two-dimensional(2D)materials have great potential in photonic and optoelectronic ***,the relatively weak light absorption in 2D materials hinders their application in practical ***,we propose a general approach to achieve angleselective perfect light absorption in 2D *** a demonstration of the concept,we experimentally show giant light absorption by placing large-area single-layer graphene on a structure consisting of a chalcogenide layer atop a mirror and achieving a total absorption of 77.6%in the mid-infrared wavelength range(~13μm),where the graphene contributes a record-high 47.2%absorptivity of mid-infrared *** of such an angle-selective thin optical element is important for solar and thermal energy harvesting,photo-detection and sensing *** study points to a new opportunity to combine 2D materials with photonic structures to enable novel device applications.

关键词： angle-selective perfect absorption angle-selective thin optical element graphene mid-infrared two-dimensional materials

Thermal photonics with broken symmetries

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eLight 2022年第1期2卷 317-336页

作者： Tianji Liu Cheng Guo Wei Li shanhui fan GPL Photonics Laboratory State Key Laboratory of Applied OpticsFine Mechanics and PhysicsChangchun Institute of OpticsChinese Academy of SciencesChangchun 130033China Department of Applied Physics Stanford UniversityStanfordCA 94305USA Department of Electrical Engineering Ginzton LaboratoryStanford UniversityStanfordCA 94305USA

Nanophotonic engineering provides an effective platform to manipulate thermal emission on-demand,enabling unprecedented heat management superior to conventional bulk *** a plethora of nanophotonic structures,symmetries play an important role in controlling radiative heat transfer in both near-field and *** physics,broken symmetries generally increase the degree of freedom in a system,enriching the understanding of physical mechanisms and bringing many exciting opportunities for novel *** this review,we discussed the underlying physics and functionalities of nanophotonic structures with broken geometrical symmetries,engineered mode symmetries,and broken reciprocity for the control of thermal *** overview a variety of physical phenomena and interesting applications,and provide the outlook for future development.

关键词： materials field symmetries