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Roitman D, Karnieli A, Tsesses S, Barkay Z, Arie A. Coherent radiation at visible wavelengths from sub-keV electron beams. OPTICS LETTERS 2024; 49:2013-2016. [PMID: 38621064 DOI: 10.1364/ol.521354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 03/21/2024] [Indexed: 04/17/2024]
Abstract
The Smith-Purcell effect allows for coherent free-electron-driven compact light sources over the entire electromagnetic spectrum. Intriguing interaction regimes, with prospects for quantum optical applications, are expected when the driving free electron enters the sub-keV range, though this has until now remained an experimental challenge. Here, we demonstrate the Smith-Purcell light emission from UV to visible using engineerable, fabricated gratings with periodicities as low as 19 nm and with electron energies as low as 300 eV. Our findings constitute a major step toward broadband, highly tunable, on-chip light sources, observation of quantum recoil effects, and tunable EUV and x ray sources from swift electrons.
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2
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Yang Y, Henke JW, Raja AS, Kappert FJ, Huang G, Arend G, Qiu Z, Feist A, Wang RN, Tusnin A, Tikan A, Ropers C, Kippenberg TJ. Free-electron interaction with nonlinear optical states in microresonators. Science 2024; 383:168-173. [PMID: 38207019 DOI: 10.1126/science.adk2489] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/17/2023] [Indexed: 01/13/2024]
Abstract
The short de Broglie wavelength and strong interaction empower free electrons to probe structures and excitations in materials and biomolecules. Recently, electron-photon interactions have enabled new optical manipulation schemes for electron beams. In this work, we demonstrate the interaction of electrons with nonlinear optical states inside a photonic chip-based microresonator. Optical parametric processes give rise to spatiotemporal pattern formation corresponding to coherent or incoherent optical frequency combs. We couple such "microcombs" to electron beams, demonstrate their fingerprints in the electron spectra, and achieve ultrafast temporal gating of the electron beam. Our work demonstrates the ability to access solitons inside an electron microscope and extends the use of microcombs to spatiotemporal control of electrons for imaging and spectroscopy.
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Affiliation(s)
- Yujia Yang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - Jan-Wilke Henke
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, D-37077 Göttingen, Germany
- Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Arslan S Raja
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - F Jasmin Kappert
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, D-37077 Göttingen, Germany
- Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Guanhao Huang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - Germaine Arend
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, D-37077 Göttingen, Germany
- Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Zheru Qiu
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - Armin Feist
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, D-37077 Göttingen, Germany
- Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Rui Ning Wang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - Aleksandr Tusnin
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - Alexey Tikan
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
| | - Claus Ropers
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, D-37077 Göttingen, Germany
- Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Tobias J Kippenberg
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, CH-1015 Lausanne, Switzerland
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3
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Dang Z, Chen Y, Fang Z. Cathodoluminescence Nanoscopy: State of the Art and Beyond. ACS NANO 2023; 17:24431-24448. [PMID: 38054434 DOI: 10.1021/acsnano.3c07593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Cathodoluminescence (CL) nanoscopy is proven to be a powerful tool to explore nanoscale optical properties, whereby free electron beams achieve a spatial resolution far beyond the diffraction limit of light. With developed methods for the control of electron beams and the collection of light, the dimension of information that CL can access has been expanded to include polarization, momentum, and time, holding promise to provide invaluable insights into the study of materials and optical near-field dynamics. With a focus on the burgeoning field of CL nanoscopy, this perspective outlines the recent advancements and applications of this technique, as illustrated by the salient experimental works. In addition, as an outlook for future research, several appealing directions that may bring about developments and discoveries are highlighted.
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Affiliation(s)
- Zhibo Dang
- School of Physics, State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, and Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, People's Republic of China
| | - Yuxiang Chen
- School of Physics, State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, and Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, People's Republic of China
| | - Zheyu Fang
- School of Physics, State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, and Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, People's Republic of China
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4
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Börm S, Davoodi F, Köhl R, Talebi N. Topological photonics by breaking the degeneracy of line node singularities in semimetal-like photonic crystals. OPTICS EXPRESS 2022; 30:42649-42662. [PMID: 36366715 DOI: 10.1364/oe.468904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Degeneracy is an omnipresent phenomenon in various physical systems, which has its roots in the preservation of geometrical symmetry. In electronic and photonic crystal systems, very often this degeneracy can be broken by virtue of strong interactions between photonic modes of the same energy, where the level repulsion and the hybridization between modes causes the emergence of photonic bandgaps. However, most often this phenomenon does not lead to a complete and inverted bandgap formation over the entire Brillouin zone. Here, by systematically breaking the symmetry of a two-dimensional square photonic crystal, we investigate the formation of Dirac points, line node singularities, and inverted bandgaps. The formation of this complete bandgap is due to the level repulsion between degenerate modes along the line nodes of a semimetal-like photonic crystal, over the entire Brillouin zone. Our numerical experiments are performed by a home-build numerical framework based on a multigrid finite element method. The developed numerical toolbox and our observations pave the way towards designing complete bandgap photonic crystals and exploring the role of symmetry on the optical behaviour of even more complicated orders in photonic crystal systems.
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5
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Karnieli A, Roitman D, Liebtrau M, Tsesses S, Van Nielen N, Kaminer I, Arie A, Polman A. Cylindrical Metalens for Generation and Focusing of Free-Electron Radiation. NANO LETTERS 2022; 22:5641-5650. [PMID: 35791573 PMCID: PMC9335868 DOI: 10.1021/acs.nanolett.1c04556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Metasurfaces constitute a powerful approach to generate and control light by engineering optical material properties at the subwavelength scale. Recently, this concept was applied to manipulate free-electron radiation phenomena, rendering versatile light sources with unique functionalities. In this Letter, we experimentally demonstrate spectral and angular control over coherent light emission by metasurfaces that interact with free-electrons under grazing incidence. Specifically, we study metalenses based on chirped metagratings that simultaneously emit and shape Smith-Purcell radiation in the visible and near-infrared spectral regime. In good agreement with theory, we observe the far-field signatures of strongly convergent and divergent cylindrical radiation wavefronts using in situ hyperspectral angle-resolved light detection in a scanning electron microscope. Furthermore, we theoretically explore simultaneous control over the polarization and wavefront of Smith-Purcell radiation via a split-ring-resonator metasurface, enabling tunable operation by spatially selective mode excitation at nanometer resolution. Our work highlights the potential of merging metasurfaces with free-electron excitations for versatile and highly tunable radiation sources in wide-ranging spectral regimes.
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Affiliation(s)
- Aviv Karnieli
- Raymond
and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dolev Roitman
- Raymond
and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Matthias Liebtrau
- Center
for Nanophotonics, NWO-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Shai Tsesses
- Andrew
and Erna Viterbi Department of Electrical Engineering, Technion−Israel Institute of Technology, Haifa 32000, Israel
| | - Nika Van Nielen
- Center
for Nanophotonics, NWO-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Ido Kaminer
- Andrew
and Erna Viterbi Department of Electrical Engineering, Technion−Israel Institute of Technology, Haifa 32000, Israel
| | - Ady Arie
- School
of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Albert Polman
- Center
for Nanophotonics, NWO-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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6
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García
de Abajo FJ, Di Giulio V. Optical Excitations with Electron Beams: Challenges and Opportunities. ACS PHOTONICS 2021; 8:945-974. [PMID: 35356759 PMCID: PMC8939335 DOI: 10.1021/acsphotonics.0c01950] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/17/2021] [Accepted: 02/19/2021] [Indexed: 05/20/2023]
Abstract
Free electron beams such as those employed in electron microscopes have evolved into powerful tools to investigate photonic nanostructures with an unrivaled combination of spatial and spectral precision through the analysis of electron energy losses and cathodoluminescence light emission. In combination with ultrafast optics, the emerging field of ultrafast electron microscopy utilizes synchronized femtosecond electron and light pulses that are aimed at the sampled structures, holding the promise to bring simultaneous sub-Å-sub-fs-sub-meV space-time-energy resolution to the study of material and optical-field dynamics. In addition, these advances enable the manipulation of the wave function of individual free electrons in unprecedented ways, opening sound prospects to probe and control quantum excitations at the nanoscale. Here, we provide an overview of photonics research based on free electrons, supplemented by original theoretical insights and discussion of several stimulating challenges and opportunities. In particular, we show that the excitation probability by a single electron is independent of its wave function, apart from a classical average over the transverse beam density profile, whereas the probability for two or more modulated electrons depends on their relative spatial arrangement, thus reflecting the quantum nature of their interactions. We derive first-principles analytical expressions that embody these results and have general validity for arbitrarily shaped electrons and any type of electron-sample interaction. We conclude with some perspectives on various exciting directions that include disruptive approaches to noninvasive spectroscopy and microscopy, the possibility of sampling the nonlinear optical response at the nanoscale, the manipulation of the density matrices associated with free electrons and optical sample modes, and appealing applications in optical modulation of electron beams, all of which could potentially revolutionize the use of free electrons in photonics.
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Affiliation(s)
- F. Javier García
de Abajo
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA-Institució
Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
- E-mail:
| | - Valerio Di Giulio
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860 Castelldefels, Barcelona, Spain
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7
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Wong LJ, Rivera N, Murdia C, Christensen T, Joannopoulos JD, Soljačić M, Kaminer I. Control of quantum electrodynamical processes by shaping electron wavepackets. Nat Commun 2021; 12:1700. [PMID: 33731697 PMCID: PMC7969958 DOI: 10.1038/s41467-021-21367-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 01/14/2021] [Indexed: 01/31/2023] Open
Abstract
Fundamental quantum electrodynamical (QED) processes, such as spontaneous emission and electron-photon scattering, encompass phenomena that underlie much of modern science and technology. Conventionally, calculations in QED and other field theories treat incoming particles as single-momentum states, omitting the possibility that coherent superposition states, i.e., shaped wavepackets, can alter fundamental scattering processes. Here, we show that free electron waveshaping can be used to design interferences between two or more pathways in a QED process, enabling precise control over the rate of that process. As an example, we show that free electron waveshaping modifies both spatial and spectral characteristics of bremsstrahlung emission, leading for instance to enhancements in directionality and monochromaticity. The ability to tailor general QED processes opens up additional avenues of control in phenomena ranging from optical excitation (e.g., plasmon and phonon emission) in electron microscopy to free electron lasing in the quantum regime.
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Affiliation(s)
- Liang Jie Wong
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
| | - Nicholas Rivera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chitraang Murdia
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Thomas Christensen
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - John D Joannopoulos
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Marin Soljačić
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ido Kaminer
- Department of Electrical Engineering, Technion, Haifa, Israel.
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8
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van Nielen N, Hentschel M, Schilder N, Giessen H, Polman A, Talebi N. Electrons Generate Self-Complementary Broadband Vortex Light Beams Using Chiral Photon Sieves. NANO LETTERS 2020; 20:5975-5981. [PMID: 32643947 DOI: 10.1021/acs.nanolett.0c01964] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Planar electron-driven photon sources have been recently proposed as miniaturized light sources, with prospects for ultrafast conjugate electron-photon microscopy and spectral interferometry. Such sources usually follow the symmetry of the electron-induced polarization: transition-radiation-based sources, for example, only generate p-polarized light. Here we demonstrate that the polarization, the bandwidth, and the directionality of photons can be tailored by utilizing photon-sieve-based structures. We design, fabricate, and characterize self-complementary chiral structures made of holes in an Au film and generate light vortex beams with specified angular momentum orders. The incoming electron interacting with the structure generates chiral surface plasmon polaritons on the structured Au surface that scatter into the far field. The outcoupled radiation interferes with transition radiation creating TE- and TM-polarized Laguerre-Gauss light beams with a chiral intensity distribution. The generated vortex light and its unique spatiotemporal features can form the basis for the generation of structured-light electron-driven photon sources.
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Affiliation(s)
- Nika van Nielen
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Mario Hentschel
- 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Nick Schilder
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Harald Giessen
- 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Albert Polman
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Nahid Talebi
- Institute of Experimental and Applied Physics, Christian Albrechts University, Leibnizstrasse 19, 24118 Kiel, Germany
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9
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Polman A, Kociak M, García de Abajo FJ. Electron-beam spectroscopy for nanophotonics. NATURE MATERIALS 2019; 18:1158-1171. [PMID: 31308514 DOI: 10.1038/s41563-019-0409-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 05/04/2019] [Accepted: 05/14/2019] [Indexed: 05/22/2023]
Abstract
Progress in electron-beam spectroscopies has recently enabled the study of optical excitations with combined space, energy and time resolution in the nanometre, millielectronvolt and femtosecond domain, thus providing unique access into nanophotonic structures and their detailed optical responses. These techniques rely on ~1-300 keV electron beams focused at the sample down to sub-nanometre spots, temporally compressed in wavepackets a few femtoseconds long, and in some cases controlled by ultrafast light pulses. The electrons undergo energy losses and gains (also giving rise to cathodoluminescence light emission), which are recorded to reveal the optical landscape along the beam path. This Review portraits these advances, with a focus on coherent excitations, emphasizing the increasing level of control over the electron wavefunctions and ensuing applications in the study and technological use of optically resonant modes and polaritons in nanoparticles, 2D materials and engineered nanostructures.
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Affiliation(s)
- Albert Polman
- Center for Nanophotonics, AMOLF, Amsterdam, the Netherlands.
| | - Mathieu Kociak
- Laboratoire de Physique des Solides, Université de Paris-Sud, Orsay, France
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
- ICREA-Institució Catalana de Reserca I Estudis Avançats, Barcelona, Spain
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