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Ilyakov IE, Shishkin BV, Efimenko ES, Bodrov SB, Bakunov MI. Experimental observation of optically generated unipolar electromagnetic precursors. OPTICS EXPRESS 2022; 30:14978-14984. [PMID: 35473230 DOI: 10.1364/oe.455768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
It was recently predicted [Phys. Rev. A95(6), 063817 (2017) 10.1103/PhysRevA.95.063817] that an intense femtosecond laser pulse propagating in an electro-optic crystal and producing free carriers via multiphoton ionization can generate a unipolar electromagnetic precursor propagating ahead of the laser pulse. Here we report the experimental observation of this phenomenon in a GaP crystal excited by an amplified Ti:sapphire laser.
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2
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Tsarev MV, Bakunov MI. Tilted-pulse-front excitation of strong quasistatic precursors. OPTICS EXPRESS 2019; 27:5154-5164. [PMID: 30876118 DOI: 10.1364/oe.27.005154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/08/2019] [Indexed: 06/09/2023]
Abstract
It was recently predicted [M. I. Bakunov, A. V. Maslov, and M. V. Tsarev, Phys. Rev. A95, 063817 (2017)10.1103/PhysRevA.95.063817] that concurrent processes of optical rectification and multiphoton absorption of an ultrashort laser pulse in an electro-optic crystal can generate a quasistatic electromagnetic precursor propagating ahead of the laser pulse. The electric and magnetic fields in the precursor can exceed the fields in the ordinary terahertz wave generated behind the laser pulse. We propose a way to enhance the precursor's magnitude tremendously, by at least two orders of magnitude, by using tilted-pulse-front excitation technique and higher orders of multiphoton absorption. In particular, we show that a pulse of 500 fs duration and 70 GW/cm2 peak intensity from a Yb-doped laser amplifier can generate in a 5-mm-thick LiNbO3 crystal a 0.5-mm-long precursor with the strengths of the electric and magnetic fields as high as 0.4 MV/cm and 0.13 T, respectively. Strong quasistatic (subterahertz) fields can be a useful tool for particle acceleration, molecular orientation, ultrafast control of magnetic order in matter, and in terahertz streaking techniques.
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Bodrov SB, Stepanov AN, Bakunov MI. Generalized analysis of terahertz generation by tilted-pulse-front excitation in a LiNbO 3 prism. OPTICS EXPRESS 2019; 27:2396-2410. [PMID: 30732278 DOI: 10.1364/oe.27.002396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/14/2019] [Indexed: 06/09/2023]
Abstract
It is commonly adopted that the widely used method of terahertz generation by tilted-pulse-front pumping of a lithium niobate crystal is optimized when both the tilted front of the pump optical pulse and the image of the diffraction grating, which introduces the tilt, are parallel to the exit surface of the crystal. We consider more general situations. In particular, we show that a deviation of the grating image plane from parallel to the crystal exit surface leads to deterioration of the terahertz beam quality but does not significantly affect the terahertz energy. If the grating image plane and the crystal exit surface are mutual parallel, but they are nonparallel to the pulse front, the terahertz beam quality remains unaffected and the terahertz energy can be unexpectedly higher (about two times for pump pulses of a ~400 fs duration) than in the standard scheme. We propose a modified design of the tilted-pulse-front scheme based on our findings.
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Zhang D, Fallahi A, Hemmer M, Wu X, Fakhari M, Hua Y, Cankaya H, Calendron AL, Zapata LE, Matlis NH, Kärtner FX. Segmented Terahertz Electron Accelerator and Manipulator (STEAM). NATURE PHOTONICS 2018; 12:336-342. [PMID: 29881446 PMCID: PMC5985934 DOI: 10.1038/s41566-018-0138-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/27/2018] [Indexed: 05/23/2023]
Abstract
Acceleration and manipulation of electron bunches underlie most electron and X-ray devices used for ultrafast imaging and spectroscopy. New terahertz-driven concepts offer orders-of-magnitude improvements in field strengths, field gradients, laser synchronization and compactness relative to conventional radio-frequency devices, enabling shorter electron bunches and higher resolution with less infrastructure while maintaining high charge capacities (pC), repetition rates (kHz) and stability. We present a segmented terahertz electron accelerator and manipulator (STEAM) capable of performing multiple high-field operations on the 6D-phase-space of ultrashort electron bunches. With this single device, powered by few-micro-Joule, single-cycle, 0.3 THz pulses, we demonstrate record THz-acceleration of >30 keV, streaking with <10 fs resolution, focusing with >2 kT/m strength, compression to ~100 fs as well as real-time switching between these modes of operation. The STEAM device demonstrates the feasibility of THz-based electron accelerators, manipulators and diagnostic tools enabling science beyond current resolution frontiers with transformative impact.
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Affiliation(s)
- Dongfang Zhang
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
- Department of Physics and The Hamburg Centre for Ultrafast Imaging,
University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Arya Fallahi
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Michael Hemmer
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Xiaojun Wu
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Moein Fakhari
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
- Department of Physics and The Hamburg Centre for Ultrafast Imaging,
University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Yi Hua
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Huseyin Cankaya
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Anne-Laure Calendron
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
- Department of Physics and The Hamburg Centre for Ultrafast Imaging,
University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Luis E. Zapata
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Nicholas H. Matlis
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Franz X. Kärtner
- Center for Free-Electron Laser Science, Deutsches Elektronen
Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
- Department of Physics and The Hamburg Centre for Ultrafast Imaging,
University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Research Laboratory of Electronics, MIT, Cambridge, 02139
Massachusetts, USA
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5
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Park W, Lee Y, Kang T, Jeong J, Kim DS. Terahertz-driven polymerization of resists in nanoantennas. Sci Rep 2018; 8:7762. [PMID: 29773858 PMCID: PMC5958088 DOI: 10.1038/s41598-018-26214-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 04/16/2018] [Indexed: 11/30/2022] Open
Abstract
Plasmon-mediated polymerization has been intensively studied for various applications including nanolithography, near-field mapping, and selective functionalization. However, these studies have been limited from the near-infrared to the ultraviolet regime. Here, we report a resist polymerization using intense terahertz pulses and various nanoantennas. The resist is polymerized near the nanoantennas, where giant field enhancement occurs. We experimentally show that the physical origin of the cross-linking is a terahertz electron emission from the nanoantenna, rather than multiphoton absorption. Our work extends nano-photochemistry into the terahertz frequencies.
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Affiliation(s)
- Woongkyu Park
- Department of Physics and Astronomy and Center for Atom Scale Electromagnetism, Seoul National University, Seoul, 151-747, Korea
| | - Youjin Lee
- Department of Physics and Astronomy and Center for Atom Scale Electromagnetism, Seoul National University, Seoul, 151-747, Korea
| | - Taehee Kang
- Department of Physics and Astronomy and Center for Atom Scale Electromagnetism, Seoul National University, Seoul, 151-747, Korea
| | - Jeeyoon Jeong
- Department of Physics and Astronomy and Center for Atom Scale Electromagnetism, Seoul National University, Seoul, 151-747, Korea
| | - Dai-Sik Kim
- Department of Physics and Astronomy and Center for Atom Scale Electromagnetism, Seoul National University, Seoul, 151-747, Korea.
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Walsh DA, Lake DS, Snedden EW, Cliffe MJ, Graham DM, Jamison SP. Demonstration of sub-luminal propagation of single-cycle terahertz pulses for particle acceleration. Nat Commun 2017; 8:421. [PMID: 28871091 PMCID: PMC5583180 DOI: 10.1038/s41467-017-00490-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 06/29/2017] [Indexed: 11/09/2022] Open
Abstract
The sub-luminal phase velocity of electromagnetic waves in free space is generally unobtainable, being closely linked to forbidden faster than light group velocities. The requirement of sub-luminal phase-velocity in laser-driven particle acceleration schemes imposes a limit on the total acceleration achievable in free space, and necessitates the use of dispersive structures or waveguides for extending the field-particle interaction. We demonstrate a travelling source approach that overcomes the sub-luminal propagation limits. The approach exploits ultrafast optical sources with slow group velocity propagation, and a group-to-phase front conversion through nonlinear optical interaction. The concept is demonstrated with two terahertz generation processes, nonlinear optical rectification and current-surge rectification. We report measurements of longitudinally polarised single-cycle electric fields with phase and group velocity between 0.77c and 1.75c. The ability to scale to multi-megavolt-per-metre field strengths is demonstrated. Our approach paves the way towards the realisation of cheap and compact particle accelerators with femtosecond scale control of particles.Controlled generation of terahertz radiation with subluminal phase velocities is a key issue in laser-driven particle acceleration. Here, the authors demonstrate a travelling-source approach utilizing the group-to-phase front conversion to overcome the sub-luminal propagation limit.
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Affiliation(s)
- D A Walsh
- Accelerator Science and Technology Centre, Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK.,The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK
| | - D S Lake
- The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK.,School of Physics and Astronomy & Photon Science Institute, The University of Manchester, Manchester, M13 9PL, UK
| | - E W Snedden
- Accelerator Science and Technology Centre, Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK.,The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK
| | - M J Cliffe
- The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK.,School of Physics and Astronomy & Photon Science Institute, The University of Manchester, Manchester, M13 9PL, UK
| | - D M Graham
- The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK.,School of Physics and Astronomy & Photon Science Institute, The University of Manchester, Manchester, M13 9PL, UK
| | - S P Jamison
- Accelerator Science and Technology Centre, Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK. .,The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington, WA4 4AD, UK.
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7
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Single-cycle surface plasmon polaritons on a bare metal wire excited by relativistic electrons. Nat Commun 2016; 7:13769. [PMID: 28008908 PMCID: PMC5196230 DOI: 10.1038/ncomms13769] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 10/25/2016] [Indexed: 11/09/2022] Open
Abstract
Terahertz (THz) pulses are applied in areas as diverse as materials science, communication and biosensing. Techniques for subwavelength concentration of THz pulses give access to a rapidly growing range of spatial scales and field intensities. Here we experimentally demonstrate a method to generate intense THz pulses on a metal wire, thereby introducing the possibility of wave-guiding and focussing of the full THz pulse energy to subwavelength spotsizes. This enables endoscopic sensing, single-shot subwavelength THz imaging and study of strongly nonlinear THz phenomena. We generate THz surface plasmon polaritons (SPPs) by launching electron bunches onto the tip of a bare metal wire. Bunches with 160 pC charge and ≈6 ps duration yield SPPs with 6–10 ps duration and 0.4±0.1 MV m−1 electric field strength on a 1.5 mm diameter aluminium wire. These are the most intense SPPs reported on a wire. The SPPs are shown to propagate around a 90° bend. Here, the authors demonstrate how ultra-short bunches of relativistic electrons produce coherent transition radiation at the tip of a thin wire. The radiation then propagates as a powerful surface plasmon polariton along the wire, illustrating the potential of this technique for terahertz plasmonics.
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Violation of the transit-time limit toward generation of ultrashort electron bunches with controlled velocity chirp. Sci Rep 2016; 6:32567. [PMID: 27653458 PMCID: PMC5032026 DOI: 10.1038/srep32567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/09/2016] [Indexed: 11/30/2022] Open
Abstract
Various methods to generate ultrashort electron bunches for the ultrafast science evolved from the simple configuration of two-plate vacuum diodes to advanced technologies such as nanotips or photocathodes excited by femtosecond lasers. In a diode either in vacuum or of solid-state, the transit-time limit originating from finite electron mobility has caused spatiotemporal bunch-collapse in ultrafast regime. Here, we show for the first time that abrupt exclusion of transit-phase is a more fundamental origin of the bunch-collapse than the transit-time limit. We found that by significantly extending the cathode-anode gap distance, thereby violating the transit-time limit, the conventional transit-time-related upper frequency barrier in diodes can be removed. Furthermore, we reveal how to control the velocity chirp of bunches leading to ballistic bunch-compression. Demonstration of 0.707 THz-, 46.4 femtosecond-bunches from a 50 μm-wide diode in three-dimensional particle-in-cell simulations shows a way toward simple and compact sources of ultrafast electron bunches for diverse ultrafast sciences.
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Wu X, Calendron AL, Ravi K, Zhou C, Hemmer M, Reichert F, Zhang D, Cankaya H, Zapata LE, Matlis NH, Kärtner FX. Optical generation of single-cycle 10 MW peak power 100 GHz waves. OPTICS EXPRESS 2016; 24:21059-21069. [PMID: 27607709 DOI: 10.1364/oe.24.021059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate the generation of 100 GHz single-cycle pulses with up to 10 MW of peak power using optical rectification and broadband phase matching via the tilted pulse front (TPF) technique in lithium niobate. The optical driver is a cryogenically cooled Yb:YAG amplifier providing tens of mJ energy, ~5 ps long laser pulses. We obtain a high THz pulse energy up to 65 µJ with 31.6 MV/m peak electric field when focused close to its diffraction limit of 2.5 mm diameter. A high optical-to-THz energy conversion efficiency of 0.3% at 85 K is measured in agreement with numerical simulations. This source is of great interest for a broad range of applications, such as nonlinear THz field-matter interaction and charged particle acceleration for ultrafast electron diffraction and table-top X-ray sources.
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Pálfalvi L, Ollmann Z, Tokodi L, Hebling J. Hybrid tilted-pulse-front excitation scheme for efficient generation of high-energy terahertz pulses. OPTICS EXPRESS 2016; 24:8156-8169. [PMID: 27137255 DOI: 10.1364/oe.24.008156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Conception of a hybrid type tilted-pulse-front pumping scheme for the generation of high-energy terahertz pulses is presented. The proposed setup is the combination of the conventional setup containing imaging optics and the contact grating. The solution was developed for nonlinear materials requiring large pulse-front-tilt angle, like LiNbO3. Due to the creation of the pulse-front-tilt in two steps the limitations of imaging errors can be significantly reduced. Furthermore the necessary grating constant of the contact grating can be larger compared to the simple contact grating scheme making possible the fabrication of the grating profile with significantly higher precision. A detailed optimization procedure with respect to the diffraction efficiency on the contact grating is given for LiNbO3. Instructions are also given how to construct the geometry of the setup in order to minimize imaging errors. Examples are given for LiNbO3 based practically realizable, optimized schemes with reduced imaging errors and high diffraction efficiency on the contact grating.
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Wu X, Zhou C, Huang WR, Ahr F, Kärtner FX. Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range. OPTICS EXPRESS 2015; 23:29729-29737. [PMID: 26698455 DOI: 10.1364/oe.23.029729] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Optical rectification with tilted pulse fronts in lithium niobate crystals is one of the most promising methods to generate terahertz (THz) radiation. In order to achieve higher optical-to-THz energy efficiency, it is necessary to cryogenically cool the crystal not only to decrease the linear phonon absorption for the generated THz wave but also to lengthen the effective interaction length between infrared pump pulses and THz waves. However, the refractive index of lithium niobate crystal at lower temperature is not the same as that at room temperature, resulting in the necessity to re-optimize or even re-build the tilted pulse front setup. Here, we performed a temperature dependent measurement of refractive index and absorption coefficient on a 6.0 mol% MgO-doped congruent lithium niobate wafer by using a THz time-domain spectrometer (THz-TDS). When the crystal temperature was decreased from 300 K to 50 K, the refractive index of the crystal in the extraordinary polarization decreased from 5.05 to 4.88 at 0.4 THz, resulting in ~1° change for the tilt angle inside the lithium niobate crystal. The angle of incidence on the grating for the tilted pulse front setup at 1030 nm with demagnification factor of -0.5 needs to be changed by 3°. The absorption coefficient decreased by 60% at 0.4 THz. These results are crucial for designing an optimum tilted pulse front setup based on lithium niobate crystals.
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