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Iwase H, Ohno S. Direct generation of a terahertz vector beam from a ZnTe crystal excited by a focused circular polarized pulse. OPTICS EXPRESS 2023; 31:26923-26934. [PMID: 37710541 DOI: 10.1364/oe.494366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 07/19/2023] [Indexed: 09/16/2023]
Abstract
A vector beam is a type of topological beam in which the polarization direction of light rotates around a singularity on the wavefront. This paper proposes a method to generate a vector beam by tightly focusing a pump beam in the crystalline direction such that the second-order nonlinear optical effect is forbidden. The directional dependence of the effective nonlinearity in zincblende crystals, such as ZnTe, was analytically investigated. Two types of nonlinear polarization singularities were found in [111] and [100] directions. Their polarization topological charge ℓ was +1 and -1, respectively. To experimentally demonstrate the proposed method, a (111) cut ZnTe crystal was selected as the nonlinear crystal. The polarization state of the generated terahertz (THz) beams was measured with a custom-built THz spectroscopic polarization imaging system. Radially polarized distributions were observed within the entire generated spectral region. Such a broadband feature of the generated vector beam is likely due to the topological nature of the focused pump beam, where the wavevectors are winding once about the optical axis. This simple method for generating THz vector beams will accelerate its applications.
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2
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Negri E, Fuscaldo W, Burghignoli P, Galli A. A Leaky-Wave Analysis of Resonant Bessel-Beam Launchers: Design Criteria, Practical Examples, and Potential Applicationsat Microwave and Millimeter-Wave Frequencies. MICROMACHINES 2022; 13:2230. [PMID: 36557529 PMCID: PMC9783674 DOI: 10.3390/mi13122230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 11/29/2022] [Accepted: 12/10/2022] [Indexed: 06/17/2023]
Abstract
Resonant Bessel-beam launchers are low-cost, planar, miniaturized devices capable of focusing electromagnetic radiation in a very efficient way in various frequency ranges, with recent increasing interest for microwave and millimeter-wave applications (i.e., 3-300 GHz). In recent years, various kinds of launchers have appeared, with different feeding mechanisms (e.g., coaxial probes, resonant slots, or loop antennas), field polarization (radial, azimuthal, and longitudinal), and manufacturing technology (axicon lenses, radial waveguides, or diffraction gratings). In this paper, we review the various features of these launchers both from a general electromagnetic background and a more specific leaky-wave interpretation. The latter allows for deriving a useful set of design rules that we here show to be applicable to any type of launcher, regardless its specific realization. Practical examples are discussed, showing a typical application of the proposed design workflow, along with a possible use of the launchers in a modern context, such as that of wireless power transfer at 90 GHz.
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Affiliation(s)
- Edoardo Negri
- Department of Information Engineering, Electronics and Telecommunications, Sapienza University of Rome, 00184 Rome, Italy
| | - Walter Fuscaldo
- Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, 00133 Rome, Italy
| | - Paolo Burghignoli
- Department of Information Engineering, Electronics and Telecommunications, Sapienza University of Rome, 00184 Rome, Italy
| | - Alessandro Galli
- Department of Information Engineering, Electronics and Telecommunications, Sapienza University of Rome, 00184 Rome, Italy
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3
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Deveikis J, Lloyd-Hughes J. Multi-pixel photoconductive emitters for the controllable generation of azimuthal and radial terahertz beams. OPTICS EXPRESS 2022; 30:43293-43300. [PMID: 36523030 DOI: 10.1364/oe.473086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 09/07/2022] [Indexed: 06/17/2023]
Abstract
A multi-pixel photoconductive emitter is reported that generates THz beams with either azimuthal, radial or linear polarization states. Switching between the different polarization states was purely electrical, via the bias voltage applied, circumventing the need for mechanical polarization optics or different THz emitters to change the polarization. Dipole array modelling was performed to validate emitter array designs, and to explore their optimal bias configuration, while spatially-resolved electro-optic detection of the generated beams confirmed that cylindrical-vector beams were produced. We further demonstrate that the spatial beam profile was optimized by adjusting the bias level on particular pixels, improving the polarization purity of the beam.
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4
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Singh A, Li J, Pashkin A, Rana R, Winnerl S, Helm M, Schneider H. High-field THz pulses from a GaAs photoconductive emitter for non-linear THz studies. OPTICS EXPRESS 2021; 29:19920-19927. [PMID: 34266092 DOI: 10.1364/oe.427247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 05/09/2021] [Indexed: 06/13/2023]
Abstract
We report the emission of high-field terahertz pulses from a GaAs large-area photoconductive emitter pumped with a Ti:Sapphire amplifier laser system at 800 nm wavelength and 1 kHz repetition rate. The maximum estimated terahertz electric field at the focus is ≳ 230 kV/cm. We also demonstrate the capability of the terahertz field to cause a non-linear effect, which usually requires high-field terahertz pulses generated through optical rectification or an air plasma. A significant drop in the optical conductivity of optically pumped GaAs due to Γ-L inter-valley scattering of free electrons caused by the strong THz field is found.
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Niwa H, Yoshikawa N, Kawaguchi M, Hayashi M, Shimano R. Switchable generation of azimuthally- and radially-polarized terahertz beams from a spintronic terahertz emitter. OPTICS EXPRESS 2021; 29:13331-13343. [PMID: 33985069 DOI: 10.1364/oe.422484] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
We propose and demonstrate a method of generating two fundamental terahertz cylindrical vector beams (THz-CVBs), namely the azimuthally- and radially-polarized THz pulses, from a spintronic THz emitter. We begin by presenting that the spintronic emitter generates the HE21 mode, a quadrupole like polarization distribution, when placed between two magnets with opposing polarity. By providing an appropriate mode conversion using a triangular Si prism, we show both from experiment and numerical calculation that we obtain azimuthal and radial THz vector beams. The proposed method facilitates the access of CVBs and paves the way toward sophisticated polarization control in the THz regime.
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6
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Isgandarov E, Ropagnol X, Singh M, Ozaki T. Intense terahertz generation from photoconductive antennas. FRONTIERS OF OPTOELECTRONICS 2021; 14:64-93. [PMID: 36637784 PMCID: PMC9743868 DOI: 10.1007/s12200-020-1081-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/16/2020] [Indexed: 06/14/2023]
Abstract
In this paper, we review the past and recent works on generating intense terahertz (THz) pulses from photoconductive antennas (PCAs). We will focus on two types of large-aperture photoconductive antenna (LAPCA) that can generate high-intensity THz pulses (a) those with large-aperture dipoles and (b) those with interdigitated electrodes. We will first describe the principles of THz generation from PCAs. The critical parameters for improving the peak intensity of THz radiation from LAPCAs are summarized. We will then describe the saturation and limitation process of LAPCAs along with the advantages and disadvantages of working with wide-bandgap semiconductor substrates. Then, we will explain the evolution of LAPCA with interdigitated electrodes, which allows one to reduce the photoconductive gap size, and thus obtain higher bias fields while applying lower voltages. We will also describe recent achievements in intense THz pulses generated by interdigitated LAPCAs based on wide-bandgap semiconductors driven by amplified lasers. Finally, we will discuss the future perspectives of THz pulse generation using LAPCAs.
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Affiliation(s)
- Elchin Isgandarov
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada
| | - Xavier Ropagnol
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada
- Département de Génie Électrique, École de Technologie Supérieure (ETS), Montréal, Québec, H3C 1K3, Canada
| | - Mangaljit Singh
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada
| | - Tsuneyuki Ozaki
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada.
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7
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Singh A, Pashkin A, Winnerl S, Welsch M, Beckh C, Sulzer P, Leitenstorfer A, Helm M, Schneider H. Up to 70 THz bandwidth from an implanted Ge photoconductive antenna excited by a femtosecond Er:fibre laser. LIGHT, SCIENCE & APPLICATIONS 2020; 9:30. [PMID: 32140221 PMCID: PMC7052201 DOI: 10.1038/s41377-020-0265-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 01/31/2020] [Accepted: 02/18/2020] [Indexed: 06/01/2023]
Abstract
Phase-stable electromagnetic pulses in the THz frequency range offer several unique capabilities in time-resolved spectroscopy. However, the diversity of their application is limited by the covered spectral bandwidth. In particular, the upper frequency limit of photoconductive emitters - the most widespread technique in THz spectroscopy - reaches only up to 7 THz in the regular transmission mode due to absorption by infrared-active optical phonons. Here, we present ultrabroadband (extending up to 70 THz) THz emission from an Au-implanted Ge emitter that is compatible with mode-locked fibre lasers operating at wavelengths of 1.1 and 1.55 μm with pulse repetition rates of 10 and 20 MHz, respectively. This result opens up the possibility for the development of compact THz photonic devices operating up to multi-THz frequencies that are compatible with Si CMOS technology.
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Affiliation(s)
- Abhishek Singh
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Alexej Pashkin
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Stephan Winnerl
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Malte Welsch
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Cfaed and Institute of Applied Physics, TU Dresden, 01062 Dresden, Germany
| | - Cornelius Beckh
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Philipp Sulzer
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Alfred Leitenstorfer
- Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany
| | - Manfred Helm
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Cfaed and Institute of Applied Physics, TU Dresden, 01062 Dresden, Germany
| | - Harald Schneider
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
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8
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Demonstration of a terahertz pure vector beam by tailoring geometric phase. Sci Rep 2018; 8:8690. [PMID: 29875483 PMCID: PMC5989212 DOI: 10.1038/s41598-018-26964-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 05/23/2018] [Indexed: 11/30/2022] Open
Abstract
We demonstrate the creation of a vector beam by tailoring geometric phase of left- and right- circularly polarized beams. Such a vector beam with a uniform phase has not been demonstrated before because a vortex phase remains in the beam. We focus on vortex phase cancellation to generate vector beams in terahertz regions, and measure the geometric phase of the beam and its spatial distribution of polarization. We conduct proof-of-principle experiments for producing a vector beam with radial polarization and uniform phase at 0.36 THz. We determine the vortex phase of the vector beam to be below 4%, thus highlighting the extendibility and availability of the proposed concept to the super broadband spectral region from ultraviolet to terahertz. The extended range of our proposed techniques could lead to breakthroughs in the fields of microscopy, chiral nano-materials, and quantum information science.
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9
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Wu Z, Wang X, Sun W, Feng S, Han P, Ye J, Zhang Y. Vector characterization of zero-order terahertz Bessel beams with linear and circular polarizations. Sci Rep 2017; 7:13929. [PMID: 29066716 PMCID: PMC5655669 DOI: 10.1038/s41598-017-12524-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/11/2017] [Indexed: 12/02/2022] Open
Abstract
As a kind of special beams, Bessel beams are always a research hot spot in optics due to its non-diffractive and self-healing properties. Here, zero-order terahertz (THz) Bessel beams with linear and circular polarizations are generated by using a THz quarter wave plate and Teflon axicons with different opening angles. By applying a THz digital holographic imaging system, the evolutions of the transverse (Ex, Ey) and longitudinal (Ez) electric fields are coherently measured and analyzed during the propagation processes of the THz Bessel beams. The vectorial Rayleigh diffraction integral is used to accurately reproduce the amplitude, phase, and non-diffractive feature of each polarization component for the THz Bessel beams. With varying opening angles of the axicons, the focal spots, diffraction-free ranges, and Gouy phase shifts of the THz Bessel beams are compared and discussed. The experiment and simulation results provide a comprehensive view for exactly understanding peculiar features of THz Bessel beams.
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Affiliation(s)
- Zhen Wu
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China
| | - Xinke Wang
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China.
| | - Wenfeng Sun
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China
| | - Shengfei Feng
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China
| | - Peng Han
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China
| | - Jiasheng Ye
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China
| | - Yan Zhang
- Beijing Key Laboratory of Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, and Department of Physics, Capital Normal University, Beijing, 100048, P.R. China
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10
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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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11
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Minasyan A, Trovato C, Degert J, Freysz E, Brasselet E, Abraham E. Geometric phase shaping of terahertz vortex beams. OPTICS LETTERS 2017; 42:41-44. [PMID: 28059173 DOI: 10.1364/ol.42.000041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We propose a topological beam-shaping strategy of terahertz (THz) beams using geometric phase elements made of space-variant birefringent slabs. Quasi-monochromatic THz vortex beams are produced and characterized both in amplitude and phase from the reconstructed real-time two-dimensional imaging of the electric field. Nonseparable superpositions of such vortex beams are also obtained and characterized by two-dimensional polarimetric analysis. These results emphasize the versatility of the spin-orbit electromagnetic toolbox to prepare on-demand structured light endowed with polarization-controlled orbital angular momentum content in the THz domain, which should find many uses in future THz technologies.
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12
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Bulgarevich DS, Watanabe M, Shiwa M, Niehues G, Kitahara H, Tani M. Polarization-variable emitter for terahertz time-domain spectroscopy. OPTICS EXPRESS 2016; 24:27160-27165. [PMID: 27906290 DOI: 10.1364/oe.24.027160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report on the progress in the development of linear polarization-variable multi-electrode emitters for terahertz time-domain spectroscopy. The results on its microfabrication, the finite element method modeling of appropriate bias distribution between electrodes, the finite-difference time-domain simulated spectral output, and actual experimental testing are presented. The rotation of the emitted terahertz field with linear polarization on an angle multiple of 45° can be achieved by synchronized bias and single polarizer rotations.
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Zheng Z, Kanda N, Konishi K, Kuwata-Gonokami M. Efficient coupling of propagating broadband terahertz radial beams to metal wires. OPTICS EXPRESS 2013; 21:10642-10650. [PMID: 23669920 DOI: 10.1364/oe.21.010642] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bare metal wires have recently been demonstrated as waveguides for transporting terahertz (THz) radiation, where the guiding mode is radially polarized surface Sommerfeld waves. In this study, we demonstrate high-efficiency coupling of a broadband radially polarized THz pulsed beam, which is generated with a polarization-controlled beam by a segmented half-wave-plate mode converter, to bare copper wires. A total coupling efficiency up to 16.8% is observed, and at 0.3 THz, the maximum coupling efficiency is 66.3%. The results of mode-overlap calculation and numerical simulation support the experimental data well.
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Affiliation(s)
- Zhu Zheng
- Centre for Quantum Technologies and Department of Physics, National University of Singapore, 3 Science Drive 2, 117543 Singapore
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14
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Wong LJ, Fallahi A, Kärtner FX. Compact electron acceleration and bunch compression in THz waveguides. OPTICS EXPRESS 2013; 21:9792-9806. [PMID: 23609686 DOI: 10.1364/oe.21.009792] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We numerically investigate the acceleration and bunch compression capabilities of 20 mJ, 0.6 THz-centered coherent terahertz pulses in optimized metallic dielectric-loaded cylindrical waveguides. In particular, we theoretically demonstrate the acceleration of 1.6 pC and 16 pC electron bunches from 1 MeV to 10 MeV over an interaction distance of 20mm, the compression of a 1.6 pC 1 MeV bunch from 100 fs to 2 fs (50 times compression) over an interaction distance of about 18mm, and the compression of a 1.6 pC 10 MeV bunch from 100 fs to 1.61 fs (62 times) over an interaction distance of 42 cm. The obtained results show the promise of coherent THz pulses in realizing compact electron acceleration and bunch compression schemes.
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Affiliation(s)
- Liang Jie Wong
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
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15
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Bitman A, Moshe I, Zalevsky Z. Improving depth-of field in broadband THz beams using nondiffractive Bessel beams. OPTICS LETTERS 2012; 37:4164-6. [PMID: 23027313 DOI: 10.1364/ol.37.004164] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report new results related to imaging using broadband Bessel-like beams at the terahertz (THz) domain that were generated by use of axicons and pulsed THz radiation emitting at a bandwidth 0.1 to 1 THz. Such Bessel-like beams exhibit an invariant line of focus with an extended length compared to Gaussian-beams Rayleigh range, which enables imaging through the extended length. We demonstrate this imaging property using a resolution target illuminated by broadband-THz beams and show an improvement by a factor of 3.5 in imaging depth while using Bessel-like beams over Gaussian beams. Our results highlight the potential in using broadband THz radiation together with nondiffractive Bessel beams to significantly improve spatial separation over deep view.
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Affiliation(s)
- Assaf Bitman
- Applied Physics Division, Soreq NRC, Yavne 81800, Israel.
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16
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Imai R, Kanda N, Higuchi T, Zheng Z, Konishi K, Kuwata-Gonokami M. Terahertz vector beam generation using segmented nonlinear optical crystals with threefold rotational symmetry. OPTICS EXPRESS 2012; 20:21896-21904. [PMID: 23037339 DOI: 10.1364/oe.20.021896] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We propose and demonstrate a simple method for cylindrical vector beam generation in the terahertz frequency region using optical rectification in segmented nonlinear crystals with threefold rotational symmetry. We used segmented GaP(111) plates to generate the terahertz cylindrical vector beam, and obtained clear evidence of the beam generation with a terahertz camera. By this method, a broadband terahertz cylindrical vector beam can be generated, and the radial and azimuth modes can be easily switched. We also report on the direct observation of the longitudinal electric field components at the focal point using a terahertz time-domain spectroscopy technique.
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Affiliation(s)
- Ryo Imai
- Department of Applied Physics, The University of Tokyo, 113-8656 Tokyo, Japan
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17
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Wen H, Lindenberg AM. Coherent terahertz polarization control through manipulation of electron trajectories. PHYSICAL REVIEW LETTERS 2009; 103:023902. [PMID: 19659205 DOI: 10.1103/physrevlett.103.023902] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Indexed: 05/28/2023]
Abstract
The dynamics of ionized electrons in a plasma can be controlled by synthetic optical fields composed of the fundamental and the second harmonic of femtosecond optical pulses with an arbitrary phase and polarization. We show here that the plasma-emitted half-cycle THz radiation directly reflects the two-dimensional trajectories of the electrons through polarization sensitive THz emission spectroscopy. As a result, we find that the THz polarization smoothly rotates through 2pi radians as the relative phase between the two pulses is adjusted, providing a new means of coherently controlling the polarization of light at THz frequencies.
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Affiliation(s)
- Haidan Wen
- PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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