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Luo Y, Su T, Yang HY, Ang YS, Ang LK. Analytical Model of Optical-Field-Driven Subcycle Electron Tunneling Pulses from Two-Dimensional Materials. NANO LETTERS 2024; 24:3882-3889. [PMID: 38527217 DOI: 10.1021/acs.nanolett.3c04928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
We develop analytical models of optical-field-driven electron tunneling from the edge and surface of free-standing two-dimensional (2D) materials. We discover a universal scaling between the tunneling current density (J) and the electric field near the barrier (F): In(J/|F|β) ∝ 1/|F| with β values of 3/2 and 1 for edge emission and vertical surface emission, respectively. At ultrahigh values of F, the current density exhibits an unexpected high-field saturation effect due to the reduced dimensionality of the 2D material, which is absent in the traditional bulk material. Our calculation reveals the dc bias as an efficient method for modulating the optical-field tunneling subcycle emission characteristics. Importantly, our model is in excellent agreement with a recent experiment on graphene. Our results offer a useful framework for understanding optical-field tunneling emission from 2D materials, which are helpful for the development of optoelectronics and emerging petahertz vacuum nanoelectronics.
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Affiliation(s)
- Yi Luo
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Tong Su
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Hui Ying Yang
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Yee Sin Ang
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Lay Kee Ang
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
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2
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Yakunin AN, Avetisyan YA, Akchurin GG, Zarkov SV, Aban’shin NP, Khanadeev VA, Tuchin VV. Photoemission of Plasmonic Gold Nanostars in Laser-Controlled Electron Current Devices for Technical and Biomedical Applications. SENSORS 2022; 22:s22114127. [PMID: 35684746 PMCID: PMC9185440 DOI: 10.3390/s22114127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 01/27/2023]
Abstract
The main goal of this work was to modify the previously developed blade-type planar structure using plasmonic gold nanostars in order to stimulate photofield emission and provide efficient laser control of the electron current. Localization and enhancement of the field at the tips of gold nanostars provided a significant increase in the tunneling electron current in the experimental sample (both electrical field and photofield emission). Irradiation at a wavelength in the vicinity of the plasmon resonance (red laser) provided a gain in the photoresponse value of up to 5 times compared to irradiation far from the resonance (green laser). The prospects for transition to regimes of structure irradiation by femtosecond laser pulses at the wavelength of surface plasmon resonance, which lead to an increase in the local optical field, are discussed. The kinetics of the energy density of photoinduced hot and thermalized electrons is estimated. The proposed laser-controlled matrix current source is promising for use in X-ray computed tomography systems.
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Affiliation(s)
- Alexander N. Yakunin
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
- Correspondence: ; Tel.: +7-845-222-2376
| | - Yury A. Avetisyan
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
| | - Garif G. Akchurin
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
- Science Medical Center, Saratov State University, 410012 Saratov, Russia
| | - Sergey V. Zarkov
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
| | | | - Vitaly A. Khanadeev
- Institute of Biochemistry and Physiology of Plants and Microorganisms, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410049 Saratov, Russia;
- Department of Microbiology, Biotechnology and Chemistry, Saratov State Agrarian University, 410012 Saratov, Russia
| | - Valery V. Tuchin
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
- Science Medical Center, Saratov State University, 410012 Saratov, Russia
- Laboratory of Laser Molecular Imaging and Machine Learning, Tomsk State University, 634050 Tomsk, Russia
- Bach Institute of Biochemistry, FRC “Fundamentals of Biotechnology of the Russian Academy of Sciences”, 119071 Moscow, Russia
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3
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Xie H. Overview of the Semiconductor Photocathode Research in China. MICROMACHINES 2021; 12:mi12111376. [PMID: 34832788 PMCID: PMC8618467 DOI: 10.3390/mi12111376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 11/30/2022]
Abstract
With the growing demand from scientific projects such as the X-ray free electron laser (XFEL), ultrafast electron diffraction/microscopy (UED/UEM) and electron ion collider (EIC), the semiconductor photocathode, which is a key technique for a high brightness electron source, has been widely studied in China. Several fabrication systems have been designed and constructed in different institutes and the vacuum of most systems is in the low 10−8 Pa level to grow a high QE and long lifetime photocathode. The QE, dark lifetime/bunch lifetime, spectral response and QE map of photocathodes with different kinds of materials, such as bialkali (K2CsSb, K2NaSb, etc.), Cs2Te and GaAs, have been investigated. These photocathodes will be used to deliver electron beams in a high voltage DC gun, a normal conducting RF gun, and an SRF gun. The emission physics of the semiconductor photocathode and intrinsic emittance reduction are also studied.
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Affiliation(s)
- Huamu Xie
- State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, Peking University, Beijing 100871, China
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4
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Yu L, Wan W, Tang WX, Feng J. Systematic analysis of a compact setup to measure the photoemitted electron beam transverse momentum and emittance. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:013302. [PMID: 33514255 DOI: 10.1063/5.0013122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 12/20/2020] [Indexed: 06/12/2023]
Abstract
A compact setup with a planar-cathode and grid-anode plus free field drift distance configuration (momentatron) has provided a new way to measure the transverse momentum and, hence, the emittance of the electron beam from a photocathode. This method has been used for analysis of the transverse momentum and emittance of the photoemitted electron beam from the photocathode in a stepwise manner during the fabrication process. The errors caused by the lensing effect from opening holes of the grid anode and misalignments caused by tilting and curving have been systematically analyzed. An analytical method has been developed, and a full three-dimensional electrostatic field particle tracing simulation has been performed to validate this measurement technique. The results show that a momentatron can provide an accurate measurement of transverse momentum and emittance of the photoemitted electrons. The reasonable experimental errors that may be encountered will only have a modest (few %) effect on the emittance measurement.
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Affiliation(s)
- Lei Yu
- College of Materials Science and Engineering, Chongqing University, Chongqing 400044, ChinaShanghaiTech University, Shanghai 201210, ChinaInstitute for Quantum Science and Engineering, South University of Science and Technology, Shenzhen 518055, Guangdong, ChinaDepartment of Materials Science and Engineering, South University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Weishi Wan
- ShanghaiTech University, Shanghai 201210, China
| | - Wen-Xin Tang
- College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
| | - Jun Feng
- Institute for Quantum Science and Engineering, South University of Science and Technology, Shenzhen 518055, Guangdong, China
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5
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Pettine J, Choo P, Medeghini F, Odom TW, Nesbitt DJ. Plasmonic nanostar photocathodes for optically-controlled directional currents. Nat Commun 2020; 11:1367. [PMID: 32170067 PMCID: PMC7069989 DOI: 10.1038/s41467-020-15115-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 02/14/2020] [Indexed: 11/20/2022] Open
Abstract
Plasmonic nanocathodes offer unique opportunities for optically driving, switching, and steering femtosecond photocurrents in nanoelectronic devices and pulsed electron sources. However, angular photocurrent distributions in nanoplasmonic systems remain poorly understood and are therefore difficult to anticipate and control. Here, we provide a direct momentum-space characterization of multiphoton photoemission from plasmonic gold nanostars and demonstrate all-optical control over these currents. Versatile angular control is achieved by selectively exciting different tips on single nanostars via laser frequency or linear polarization, thereby rotating the tip-aligned directional photoemission as observed with angle-resolved 2D velocity mapping and 3D reconstruction. Classical plasmonic field simulations combined with quantum photoemission theory elucidate the role of surface-mediated nonlinear excitation for plasmonic field enhancements highly concentrated at the sharp tips (Rtip = 3.4 nm). We thus establish a simple mechanism for femtosecond spatiotemporal current control in designer nanosystems.
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Affiliation(s)
- Jacob Pettine
- JILA, University of Colorado Boulder and National Institute of Standards and Technology, Boulder, CO, 80309, USA
- Department of Physics, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Priscilla Choo
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Fabio Medeghini
- JILA, University of Colorado Boulder and National Institute of Standards and Technology, Boulder, CO, 80309, USA
| | - Teri W Odom
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA.
| | - David J Nesbitt
- JILA, University of Colorado Boulder and National Institute of Standards and Technology, Boulder, CO, 80309, USA.
- Department of Physics, University of Colorado Boulder, Boulder, CO, 80309, USA.
- Department of Chemistry, University of Colorado Boulder, Boulder, CO, 80309, USA.
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6
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Lang P, Song X, Ji B, Tao H, Dou Y, Gao X, Hao Z, Lin J. Spatial- and energy-resolved photoemission electron from plasmonic nanoparticles in multiphoton regime. OPTICS EXPRESS 2019; 27:6878-6891. [PMID: 30876264 DOI: 10.1364/oe.27.006878] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/21/2019] [Indexed: 05/27/2023]
Abstract
Spatial-resolved photoelectron spectra have been observed from plasmonic metallic nanostructure and flat metal surface by a combination of time-of-flight photoemission electron microscope and femtosecond laser oscillator. The photoemission's main contribution is at localized 'hot spots,' where the plasmonic effect dominates and multiphoton photoemission is confirmed as the responsible mechanism for emission in both samples. Photoelectron spectra from hot spots exponentially decay in high energy regimes, smearing out the Fermi edge in Au flat surface. This phenomenon is explained by the emergence of above threshold photoemission that is induced by plasmonic effect; other competing mechanisms are ruled out. It is the first time that we have observed the emergence of high kinetic energy photoelectron in weak field region around 'hot spot.' We attribute the emergence of high kinetic energy photoelectron to the drifting of the liberated electron from plasmonic hot spot and driven by the gradient of plasmonic field.
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7
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Green ME, Bas DA, Yao HY, Gengler JJ, Headrick RJ, Back TC, Urbas AM, Pasquali M, Kono J, Her TH. Bright and Ultrafast Photoelectron Emission from Aligned Single-Wall Carbon Nanotubes through Multiphoton Exciton Resonance. NANO LETTERS 2019; 19:158-164. [PMID: 30484322 DOI: 10.1021/acs.nanolett.8b03564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ultrashort bunches of electrons, emitted from solid surfaces through excitation by ultrashort laser pulses, are an essential ingredient in advanced X-ray sources, and ultrafast electron diffraction and spectroscopy. Multiphoton photoemission using a noble metal as the photocathode material is typically used but more brightness is desired. Artificially structured metal photocathodes have been shown to enhance optical absorption via surface plasmon resonance but such an approach severely reduces the damage threshold in addition to requiring state-of-the-art facilities for photocathode fabrication. Here, we report ultrafast photoelectron emission from sidewalls of aligned single-wall carbon nanotubes. We utilized strong exciton resonances inherent in this prototypical one-dimensional material, and its excellent thermal conductivity and mechanical rigidity leading to a high damage threshold. We obtained unambiguous evidence for resonance-enhanced multiphoton photoemission processes with definite power-law behaviors. In addition, we observed strong polarization dependence and ultrashort photoelectron response time, both of which can be quantitatively explained by our model. These results firmly establish aligned single-wall carbon nanotube films as novel and promising ultrafast photocathode material.
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Affiliation(s)
- Mark E Green
- Department of Physics and Optical Science , UNC Charlotte , Charlotte , North Carolina 28223 , United States
| | - Derek A Bas
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Hsin-Yu Yao
- Department of Physics , National Tsing Hua University , No. 101, Section 2, Kuang-Fu Road , Hsinchu , Taiwan
| | - Jamie J Gengler
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | | | - Tyson C Back
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Augustine M Urbas
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | | | | | - Tsing-Hua Her
- Department of Physics and Optical Science , UNC Charlotte , Charlotte , North Carolina 28223 , United States
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8
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Lang P, Ji B, Song X, Dou Y, Tao H, Gao X, Hao Z, Lin J. Ultrafast switching of photoemission electron through quantum pathways interference in metallic nanostructure. OPTICS LETTERS 2018; 43:5721-5724. [PMID: 30499977 DOI: 10.1364/ol.43.005721] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 10/20/2018] [Indexed: 06/09/2023]
Abstract
The localized photoemission electron originating from the plasmonic "hot spots" in a metallic bowtie nanostructure can be separately switched on and off by adjusting the relative time delay between two orthogonally polarized laser pulses. The demonstrated femtosecond timing, nanometric spatial switching of multiphoton photoemission results from the interference of quantum pathways. Energy resolved measurement of the photoemission electrons further shows that the quantum pathway interference mechanism applies to control all the liberated electrons. The experimental results also show that the probability of electron emission through the quantum pathways from a plasmonic hot spot is determined by the localized emission response to the two incident laser pulses. These findings are of importance for controlling photoemission in ultrahigh spatiotemporal resolution in metallic plasmonic nanostructures.
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9
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Budai J, Pápa Z, Márton I, Wróbel P, Stefaniuk T, Márton Z, Rácz P, Dombi P. Plasmon-plasmon coupling probed by ultrafast, strong-field photoemission with <7 Å sensitivity. NANOSCALE 2018; 10:16261-16267. [PMID: 30124717 DOI: 10.1039/c8nr04242j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The coupling of propagating surface plasmon waves and localized plasmon oscillations in nanostructures is an essential phenomenon determining electromagnetic field enhancement on the nanoscale. Here, we use our recently developed ultrafast photoemission near-field probing technique to investigate the fundamental question of plasmon-plasmon coupling and its effect on large field enhancement factors. By measuring and analyzing plasmon field enhancement values at different nanostructured surfaces, we can separate the contributions from propagating and localized plasmons. When resonance conditions are met, a significant field enhancement factor can be attributed to the generation of localized plasmons on surface nanostructures, acting as dipole sources resonantly driven by the propagating plasmon field. Our plasmon-plasmon coupling results can contribute directly to applications in surface-enhanced Raman scattering (SERS) and the development of plasmonic sensors and nanostructured photocathodes.
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Affiliation(s)
- Judit Budai
- ELI-ALPS Research Institute, ELI-HU Non-Profit Ltd., 6720 Szeged, Hungary. and Department of Optics and Quantum Electronics, University of Szeged, 6720 Szeged, Hungary
| | - Zsuzsanna Pápa
- ELI-ALPS Research Institute, ELI-HU Non-Profit Ltd., 6720 Szeged, Hungary. and MTA "Lendület" Ultrafast Nanooptics Group, Wigner Research Centre for Physics, 1121 Budapest, Hungary
| | - István Márton
- MTA "Lendület" Ultrafast Nanooptics Group, Wigner Research Centre for Physics, 1121 Budapest, Hungary
| | - Piotr Wróbel
- Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland
| | | | - Zsuzsanna Márton
- ELI-ALPS Research Institute, ELI-HU Non-Profit Ltd., 6720 Szeged, Hungary. and Department of Experimental Physics, University of Pécs, 7624 Pécs, Hungary
| | - Péter Rácz
- MTA "Lendület" Ultrafast Nanooptics Group, Wigner Research Centre for Physics, 1121 Budapest, Hungary
| | - Péter Dombi
- ELI-ALPS Research Institute, ELI-HU Non-Profit Ltd., 6720 Szeged, Hungary. and MTA "Lendület" Ultrafast Nanooptics Group, Wigner Research Centre for Physics, 1121 Budapest, Hungary
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10
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Gong Y, Joly AG, Zhang X, El-Khoury PZ, Hess WP. Surface Plasmon Coupling and Control Using Spherical Cap Structures. J Phys Chem Lett 2017; 8:2695-2699. [PMID: 28562047 DOI: 10.1021/acs.jpclett.7b00852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Propagating surface plasmons (PSPs) launched from a protruded silver spherical cap structure are investigated using photoemission electron microscopy (PEEM) and finite difference time domain (FDTD) calculations. Our combined experimental and theoretical findings reveal that PSP coupling efficiency is comparable to conventional etched-in plasmonic coupling structures. Additionally, plasmon propagation direction can be varied by linear rotation of the driving laser polarization. A simple geometric model is proposed in which the plasmon direction selectivity is proportional to the projection of the linear laser polarization on the surface normal. A application for the spherical cap coupler as a gate device is proposed. Overall, our results indicate that protruded cap structures hold great promise as elements in emerging surface plasmon applications.
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Affiliation(s)
- Yu Gong
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Alan G Joly
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Xin Zhang
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Patrick Z El-Khoury
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Wayne P Hess
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
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11
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Gong Y, Joly AG, El-Khoury PZ, Hess WP. Polarization-Directed Surface Plasmon Polariton Launching. J Phys Chem Lett 2017; 8:49-54. [PMID: 27936754 DOI: 10.1021/acs.jpclett.6b02509] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The relative intensities of propagating surface plasmons (PSPs) simultaneously launched from opposing edges of a symmetric trench structure etched into a silver thin film may be controllably varied by tuning the linear polarization of the driving field. This is demonstrated through transient multiphoton photoemission electron microscopy measurements performed using a pair of spatially separated phase-locked femtosecond pulses. Our measurements are rationalized using finite-difference time domain simulations, which reveal that the coupling efficiency into the PSP modes is inversely proportional to the magnitude of the localized surface plasmon fields excited at the trench edges. Our combined experimental and computational results allude to the interplay between localized and propagating surface plasmon modes in the trench; strong coupling to the localized modes at the edges correlates to weak coupling to the PSP modes. Polarization-directed PSP launching measurements reveal an optimal PSP contrast ratio of 4.2 using a 500 nm wide trench.
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Affiliation(s)
- Yu Gong
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Alan G Joly
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Patrick Z El-Khoury
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Wayne P Hess
- Physical Sciences Division, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
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12
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Hobbs RG, Manfrinato VR, Yang Y, Goodman SA, Zhang L, Stach EA, Berggren KK. High-Energy Surface and Volume Plasmons in Nanopatterned Sub-10 nm Aluminum Nanostructures. NANO LETTERS 2016; 16:4149-4157. [PMID: 27295061 DOI: 10.1021/acs.nanolett.6b01012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, we use electron energy-loss spectroscopy to map the complete plasmonic spectrum of aluminum nanodisks with diameters ranging from 3 to 120 nm fabricated by high-resolution electron-beam lithography. Our nanopatterning approach allows us to produce localized surface plasmon resonances across a wide spectral range spanning 2-8 eV. Electromagnetic simulations using the finite element method support the existence of dipolar, quadrupolar, and hexapolar surface plasmon modes as well as centrosymmetric breathing modes depending on the location of the electron-beam excitation. In addition, we have developed an approach using nanolithography that is capable of meV control over the energy and attosecond control over the lifetime of volume plasmons in these nanodisks. The precise measurement of volume plasmon lifetime may also provide an opportunity to probe and control the DC electrical conductivity of highly confined metallic nanostructures. Lastly, we show the strong influence of the nanodisk boundary in determining both the energy and lifetime of surface plasmons and volume plasmons locally across individual aluminum nanodisks, and we have compared these observations to similar effects produced by scaling the nanodisk diameter.
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Affiliation(s)
- Richard G Hobbs
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Vitor R Manfrinato
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Yujia Yang
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Sarah A Goodman
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Lihua Zhang
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Eric A Stach
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Karl K Berggren
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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13
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Dong CD, Swanwick ME, Keathley PD, Kärtner FX, Velásquez-García LF. Multiplexing and scaling-down of nanostructured photon-triggered silicon field emitter arrays for maximum total electron yield. NANOTECHNOLOGY 2015; 26:265202. [PMID: 26057050 DOI: 10.1088/0957-4484/26/26/265202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Femtosecond ultrabright cathodes with spatially structured emission are a critical technology for applications such as free-electron lasers, tabletop coherent x-ray sources, and ultrafast imaging. In this work, the optimization of the total electron yield of ultrafast photon-triggered field emission cathodes composed of arrays of nanosharp, high-aspect-ratio, single-crystal silicon pillars is explored through the variation of the emitter pitch and height. Arrays of 6 nm tip radius silicon emitters with emitter densities between 1.2 and 73.9 million tips cm(-2) (hexagonally packed arrays with emitter pitch between 1.25 and 10 μm) and emitter height between 2.0 and 8.5 μm were characterized using 35 fs 800 nm laser pulses. Three-photon electron emission for low-energy (<0.3 μJ) light pulses and strong-field emission for high-energy (>1 μJ) light pulses was observed, in agreement with the literature. Of the devices tested, the arrays with emitter pitch equal to 2.5 μm produced the highest total electron yield; arrays with larger emitter pitch suffer area sub-utilization, and in devices with smaller emitter pitch the larger emitter density does not compensate the smaller per-emitter current due to the electric field shadowing that results from the proximity of the adjacent tips. Experimental data and simulations suggest that 2 μm tall emitters achieve practical optimal performance as shorter emitters have visibly smaller field factors due to the proximity of the emitter tip to the substrate, and taller emitters show marginal improvement in the electron yield at the expense of greater fabrication difficulty.
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Affiliation(s)
- Chen D Dong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
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14
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Gong Y, Joly AG, Hu D, El-Khoury PZ, Hess WP. Ultrafast imaging of surface plasmons propagating on a gold surface. NANO LETTERS 2015; 15:3472-3478. [PMID: 25844522 DOI: 10.1021/acs.nanolett.5b00803] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We record time-resolved nonlinear photoemission electron microscopy (tr-PEEM) images of propagating surface plasmons (PSPs) launched from a lithographically patterned rectangular trench on a flat gold surface. Our tr-PEEM scheme involves a pair of identical, spatially separated, and interferometrically locked femtosecond laser pulses. Power-dependent PEEM images provide experimental evidence for a sequential coherent nonlinear photoemission process, in which one laser source launches a PSP through a linear interaction, and the second subsequently probes the PSP via two-photon photoemission. The recorded time-resolved movies of a PSP allow us to directly measure various properties of the surface-bound wave packet, including its carrier wavelength (783 nm) and group velocity (0.95c). In addition, tr-PEEM images reveal that the launched PSP may be detected at least 250 μm away from the coupling trench structure.
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Affiliation(s)
- Yu Gong
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Alan G Joly
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Dehong Hu
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Patrick Z El-Khoury
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Wayne P Hess
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
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15
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Kong L, Joly AG, Droubay TC, Hess WP. Quantum efficiency enhancement in CsI/metal photocathodes. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Törmä P, Barnes WL. Strong coupling between surface plasmon polaritons and emitters: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:013901. [PMID: 25536670 DOI: 10.1088/0034-4885/78/1/013901] [Citation(s) in RCA: 451] [Impact Index Per Article: 50.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In this review we look at the concepts and state-of-the-art concerning the strong coupling of surface plasmon-polariton modes to states associated with quantum emitters such as excitons in J-aggregates, dye molecules and quantum dots. We explore the phenomenon of strong coupling with reference to a number of examples involving electromagnetic fields and matter. We then provide a concise description of the relevant background physics of surface plasmon polaritons. An extensive overview of the historical background and a detailed discussion of more recent relevant experimental advances concerning strong coupling between surface plasmon polaritons and quantum emitters is then presented. Three conceptual frameworks are then discussed and compared in depth: classical, semi-classical and fully quantum mechanical; these theoretical frameworks will have relevance to strong coupling beyond that involving surface plasmon polaritons. We conclude our review with a perspective on the future of this rapidly emerging field, one we are sure will grow to encompass more intriguing physics and will develop in scope to be of relevance to other areas of science.
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Affiliation(s)
- P Törmä
- Department of Applied Physics, COMP Centre of Excellence, Aalto University, FI-00076 Aalto, Finland
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17
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Hobbs RG, Yang Y, Fallahi A, Keathley PD, De Leo E, Kärtner FX, Graves WS, Berggren KK. High-yield, ultrafast, surface plasmon-enhanced, Au nanorod optical field electron emitter arrays. ACS NANO 2014; 8:11474-82. [PMID: 25380557 DOI: 10.1021/nn504594g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Here we demonstrate the design, fabrication, and characterization of ultrafast, surface-plasmon enhanced Au nanorod optical field emitter arrays. We present a quantitative study of electron emission from Au nanorod arrays fabricated by high-resolution electron-beam lithography and excited by 35 fs pulses of 800 nm light. We present accurate models for both the optical field enhancement of Au nanorods within high-density arrays, and electron emission from those nanorods. We have also studied the effects of surface plasmon damping induced by metallic interface layers at the substrate/nanorod interface on near-field enhancement and electron emission. We have identified the peak optical field at which the electron emission mechanism transitions from a 3-photon absorption mechanism to strong-field tunneling emission. Moreover, we have investigated the effects of nanorod array density on nanorod charge yield, including measurement of space-charge effects. The Au nanorod photocathodes presented in this work display 100-1000 times higher conversion efficiency relative to previously reported UV triggered emission from planar Au photocathodes. Consequently, the Au nanorod arrays triggered by ultrafast pulses of 800 nm light in this work may outperform equivalent UV-triggered Au photocathodes, while also offering nanostructuring of the electron pulse produced from such a cathode, which is of interest for X-ray free-electron laser (XFEL) development where nanostructured electron pulses may facilitate more efficient and brighter XFEL radiation.
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Affiliation(s)
- Richard G Hobbs
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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18
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Hobbs RG, Yang Y, Keathley PD, Swanwick ME, Velásquez-Garcíia LF, Kärtner FX, Graves WS, Berggren KK. High-density Au nanorod optical field-emitter arrays. NANOTECHNOLOGY 2014; 25:465304. [PMID: 25354583 DOI: 10.1088/0957-4484/25/46/465304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m(-1), and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer.
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Affiliation(s)
- R G Hobbs
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
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19
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Karkare S, Boulet L, Cultrera L, Dunham B, Liu X, Schaff W, Bazarov I. Ultrabright and ultrafast III-V semiconductor photocathodes. PHYSICAL REVIEW LETTERS 2014; 112:097601. [PMID: 24655275 DOI: 10.1103/physrevlett.112.097601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Indexed: 06/03/2023]
Abstract
Crucial photoemission properties of layered III-V semiconductor cathodes are predicted using Monte Carlo simulations. Using this modeling, a layered GaAs structure is designed to reduce simultaneously the transverse energy and response time of the emitted electrons. This structure, grown by molecular beam epitaxy and activated to negative electron affinity, is characterized. The measured values of quantum efficiency and transverse energy are found to agree well with the simulations. Such advanced layered structures will allow generation of short electron bunches from photoinjectors with superior beam brightness.
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Affiliation(s)
| | | | - Luca Cultrera
- CLASSE, Cornell University, Ithaca, New York 14853, USA
| | - Bruce Dunham
- CLASSE, Cornell University, Ithaca, New York 14853, USA
| | - Xianghong Liu
- CLASSE, Cornell University, Ithaca, New York 14853, USA
| | | | - Ivan Bazarov
- CLASSE, Cornell University, Ithaca, New York 14853, USA
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20
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Lin J, He W, Vilayurganapathy S, Peppernick SJ, Wang B, Palepu S, Remec M, Hess WP, Hmelo AB, Pantelides ST, Dickerson JH. Growth of Solid and Hollow Gold Particles through the Thermal Annealing of Nanoscale Patterned Thin Films. ACS APPLIED MATERIALS & INTERFACES 2013; 5:11590-11596. [PMID: 24144267 DOI: 10.1021/am402633u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Through thermally annealing well-arrayed, circular, nanoscale thin films of gold, deposited onto [111] silicon/silicon dioxide substrates, both solid and hollow gold particles of different morphologies with controllable sizes were obtained. The circular thin films formed individual particles or clusters of particles by tuning their diameter. Hollow gold particles were characterized by their diameter, typically larger than 400 nm; these dimensions and properties were confirmed by cross-section scanning electron microscopy. Hollow gold particles also exhibited plasmonic field enhancement under photoemission electron microscopy. Potential growth mechanisms for these structures were explored.
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Affiliation(s)
- Junhao Lin
- Department of Physics and Astronomy, Vanderbilt University , Nashville, Tennessee 37235-1807, United States
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21
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Breuer J, Hommelhoff P. Laser-based acceleration of nonrelativistic electrons at a dielectric structure. PHYSICAL REVIEW LETTERS 2013; 111:134803. [PMID: 24116785 DOI: 10.1103/physrevlett.111.134803] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Indexed: 06/02/2023]
Abstract
A proof-of-principle experiment demonstrating dielectric laser acceleration of nonrelativistic electrons in the vicinity of a fused-silica grating is reported. The grating structure is utilized to generate an electromagnetic surface wave that travels synchronously with and efficiently imparts momentum on 28 keV electrons. We observe a maximum acceleration gradient of 25 MeV/m. We investigate in detail the parameter dependencies and find excellent agreement with numerical simulations. With the availability of compact and efficient fiber laser technology, these findings may pave the way towards an all-optical compact particle accelerator. This work also represents the demonstration of the inverse Smith-Purcell effect in the optical regime.
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Affiliation(s)
- John Breuer
- Max Planck Institute of Quantum Optics, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
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22
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Feng J, Nasiatka J, Wong J, Chen X, Hidalgo S, Vecchione T, Zhu H, Javier Palomares F, Padmore HA. A stigmatic ultraviolet-visible monochromator for use with a high brightness laser driven plasma light source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:085114. [PMID: 24007114 DOI: 10.1063/1.4817587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Laser driven plasma light sources offer highly intense output in the UV-visible region combined with a source size as small as 100 μm. In order to effectively use the small source size in high brightness applications, a stigmatic monochromator and focusing system must be used. Here we describe a simple brightness preserving optical system that should be useful across a broad range of applications. The output flux of this system is between 6 × 10(11) ph∕s and 4 × 10(12) ph∕s with a spectra resolution of 1.7 nm and field spot size of 0.1 mm from the UV to the VIS spectra range.
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Affiliation(s)
- Jun Feng
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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23
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Melli M, Polyakov A, Gargas D, Huynh C, Scipioni L, Bao W, Ogletree DF, Schuck PJ, Cabrini S, Weber-Bargioni A. Reaching the theoretical resonance quality factor limit in coaxial plasmonic nanoresonators fabricated by helium ion lithography. NANO LETTERS 2013; 13:2687-2691. [PMID: 23617768 DOI: 10.1021/nl400844a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Optical antenna structures have revolutionized the field of nano-optics by confining light to deep subwavelength dimensions for spectroscopy and sensing. In this work, we fabricated coaxial optical antennae with sub-10-nanometer critical dimensions using helium ion lithography (HIL). Wavelength dependent transmission measurements were used to determine the wavelength-dependent optical response. The quality factor of 11 achieved with our HIL fabricated structures matched the theoretically predicted quality factor for the idealized flawless gold resonators calculated by finite-difference time-domain (FDTD). For comparison, coaxial antennae with 30 nm critical dimensions were fabricated using both HIL and the more common Ga focus ion beam lithography (Ga-FIB). The quality factor of the Ga-FIB resonators was 60% of the ideal HIL results for the same design geometry due to limitations in the Ga-FIB fabrication process.
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Affiliation(s)
- M Melli
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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