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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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2
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Downes LA, Whiting DJ, Adams CS, Weatherill KJ. Rapid readout of terahertz orbital angular momentum beams using atom-based imaging. OPTICS LETTERS 2022; 47:6001-6004. [PMID: 37219157 DOI: 10.1364/ol.476945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 10/24/2022] [Indexed: 05/24/2023]
Abstract
We demonstrate the rapid readout of terahertz orbital angular momentum (OAM) beams using an atomic-vapor-based imaging technique. OAM modes with both azimuthal and radial indices are created using phase-only transmission plates. The beams undergo terahertz-to-optical conversion in an atomic vapor, before being imaged in the far field using an optical CCD camera. In addition to the spatial intensity profile, we also observe the self-interferogram of the beams by imaging through a tilted lens, allowing the sign and magnitude of the azimuthal index to be read out directly. Using this technique, we can reliably read out the OAM mode of low-intensity beams with high fidelity in 10 ms. Such a demonstration is expected to have far-reaching consequences for proposed applications of terahertz OAM beams in communications and microscopy.
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3
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Yang LJ, Li JS. Terahertz vortex beam generator carrying orbital angular momentum in both transmission and reflection spaces. OPTICS EXPRESS 2022; 30:36960-36972. [PMID: 36258615 DOI: 10.1364/oe.472577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
Vortex beam generators carrying orbital angular momentum (OAM) with both transmission and reflection modes has broad application prospects in full-space high data capacity communication and orbital angular momentum multiplexing systems. In this work, we proposed a vanadium dioxide (VO2) assisted metasurface to independently produce and manipulate focused vortex transmission-reflection modes with different number of beams and focal lengths under right-handed circular polarized (RCP) wave incidence. The proposed metasurface generates the diagonal vortex beams, four vortex beams, and focused vortex beam for transmission mode at 1.26THz and reflection mode at 1.06THz by changing phase state of the VO2. Our work may find many potential applications in future high data capacity information multiplexing communication systems.
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Koral C, Mazaheri Z, Andreone A. THz Multi-Mode Q-Plate with a Fixed Rate of Change of the Optical Axis Using Form Birefringence. MICROMACHINES 2022; 13:mi13050796. [PMID: 35630263 PMCID: PMC9144830 DOI: 10.3390/mi13050796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 02/01/2023]
Abstract
We report the design, fabrication and experimental validation of a THz all-dielectric multi-mode q-plate having a fixed rate of change of the optical axis. The device consists of space-variant birefringent slabs manufactured by 3D printing using melt-extruded Acrylonitrile Butadiene Styrene (ABS). The desired form birefringence is analytically evaluated and experimentally measured by the THz time domain spectroscopy technique. The manufactured q-plate design is characterized using a polarization-sensitive imaging setup. The full electric field spatial maps are acquired from the beam propagating through the q-plate. The device enables the realization of both radial and azimuthal vector beams at discrete frequency intervals by controlling the space-dependent orientation of the ordinary and extraordinary axes in the transverse plane with a multi-mode sequence.
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Affiliation(s)
- Can Koral
- Department of Physics, University of Naples Federico II, 80126 Naples, Italy; (Z.M.); (A.A.)
- Naples Unit, National Institute of Nuclear Physics, 80126 Naples, Italy
- Correspondence:
| | - Zahra Mazaheri
- Department of Physics, University of Naples Federico II, 80126 Naples, Italy; (Z.M.); (A.A.)
| | - Antonello Andreone
- Department of Physics, University of Naples Federico II, 80126 Naples, Italy; (Z.M.); (A.A.)
- Naples Unit, National Institute of Nuclear Physics, 80126 Naples, Italy
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5
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Sharma V, Chaitanya Kumar S, Samanta GK, Ebrahim-Zadeh M. Tunable, high-power, high-order optical vortex beam generation in the mid-infrared. OPTICS EXPRESS 2022; 30:1195-1204. [PMID: 35209284 DOI: 10.1364/oe.443345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
We report the generation of tunable high-order optical vortices in the mid-infrared (mid-IR) using a picosecond optical parametric oscillator (OPO). The OPO is based on MgO:PPLN as the nonlinear gain medium and synchronously pumped by a mode-locked Yb-fiber laser at 1064 nm. Using a singly-resonant oscillator configuration for the OPO, we have achieved direct transfer of pump optical vortices to the non-resonant idler beam, with the resonant signal in the Gaussian cavity mode. We demonstrate the successful transfer of pump optical vortices of order, lp = 1 to 5, to the idler beam of the same order across the mid-IR, with an output power of 630 mW to 130 mW across 2538 nm to 4035 nm for the highest idler vortex order, li = 5. To the best of our knowledge, this is the first report of an OPO pumped by a vortex beam of order as high as lp = 5 and generating idler vortices of high order in the mid-IR.
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Troha T, Ostatnický T, Kužel P. Improving security in terahertz wireless links using beam symmetry of vortex and Gaussian beams. OPTICS EXPRESS 2021; 29:30461-30472. [PMID: 34614769 DOI: 10.1364/oe.433606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
We present an effective way to improve the security of a point-to-point terahertz wireless link on a physical layer supported by numerical calculations in the frame of Fourier optics. The improvement is based on original countermeasures which exploit three independent degrees of freedom of the carrier wave: its intensity and azimuthal and radial symmetry. When the transmission line is intercepted, the light beam is subject to changes in either of the three degrees of freedom. We propose a strategy to measure these changes and they are quantified by a single eavesdropping parameter that is shown to be correlated to the secrecy capacity of the transmission. Consequently, its excessive value serves as an indication of the beam interception. We consider the carrier wave in the form of Gaussian and vortex beams. Comparison between the two reveals that vortex beam ensures a even higher level of security.
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He X, Yang Y, Deng L, Li S, Feng B. 3D Printed Sub-Terahertz All-Dielectric Lens for Arbitrary Manipulation of Quasi-Nondiffractive Orbital Angular Momentum Waves. ACS APPLIED MATERIALS & INTERFACES 2021; 13:20770-20778. [PMID: 33886275 DOI: 10.1021/acsami.1c01443] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Terahertz (THz) vortex waves carrying orbital angular momentum (OAM) hold great potential in dealing with the capacity crunch in wireless high-speed communication systems. Nevertheless, it is quite a challenge for the widespread applications of OAM in the THz regime due to the beam divergence and stringent alignment requirement. To address this issue, an all-dielectric lens (ADL) is proposed for the arbitrary manipulation of quasi-nondiffractive THz OAM waves (QTOWs). On the basis of the concept of the optical conical lens and the multivorticity metasurface, the beam number, the topological charge (TC), and the deflection angle as well as the nondiffractive depth of the generated THz OAM waves are controllable. For proof-of-concept, two ADLs are 3D printed to create single and dual deflected QTOWs, respectively. Remarkably, measured by a THz imaging camera, the desired QTOWs with high mode purity are observed in predesigned directions with a nondiffractive depth predefined theoretically. The proposed designs and experiments, for the first time, verified that the QTOWs could be achieved with a nondiffractive range of 55.58λg (λg = wavelength at 140 GHz) and large deflection angles of 30° and 45°.
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Affiliation(s)
- Xiaoyuan He
- Beijing Laboratory of Advanced Information Networks and Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100089, China
| | - Yang Yang
- Tech Lab, School of Electrical and Data Engineering, University of Technology Sydney, Botany, New South Wales 2019, Australia
| | - Li Deng
- Beijing Laboratory of Advanced Information Networks and Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100089, China
| | - Shufang Li
- Beijing Laboratory of Advanced Information Networks and Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100089, China
| | - Botao Feng
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, Guangdong 518060, China
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Ring-Core Photonic Crystal Fiber of Terahertz Orbital Angular Momentum Modes with Excellence Guiding Properties in Optical Fiber Communication. PHOTONICS 2021. [DOI: 10.3390/photonics8040122] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The orbital angular momentum (OAM) of light is used for increasing the optical communication capacity in the mode division multiplexing (MDM) technique. A novel and simple structure of ring-core photonic crystal fiber (RC-PCF) is proposed in this paper. The ring core is doped by the Schott sulfur difluoride material and the cladding region is composed of fused silica with one layer of well-patterned air-holes. The guiding of Terahertz (THz) OAM beams with 58 OAM modes over 0.70 THz (0.20 THz–0.90 THz) frequency is supported by this proposed RC-PCF. The OAM modes are well-separated for their large refractive index difference above 10−4. The dispersion profile of each mode is varied in the range of 0.23–7.77 ps/THz/cm. The ultra-low confinement loss around 10−9 dB/cm and better mode purity up to 0.932 is achieved by this RC-PCF. For these good properties, the proposed fiber is a promising candidate to be applied in the THz OAM transmission systems with high feasibility and high capacity.
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Zhang Z, Dai Z, Wang Y, Chu C, Su Q, Kosareva O, Zhang N, Lin L, Liu W. Fabricating THz spiral zone plate by high throughput femtosecond laser air filament direct writing. Sci Rep 2020; 10:13965. [PMID: 32811898 PMCID: PMC7434771 DOI: 10.1038/s41598-020-70997-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/04/2020] [Indexed: 11/09/2022] Open
Abstract
The sixth-generation wireless communication will exploit the radio band with frequencies higher than 90 GHz, reaching terahertz (THz) band, to achieve huge signal bandwidths. However, the cost-effective fabrication methods of the key components in THz band, which can compromise large scale, high precision, and high efficiency, remain great challenges at present. In this work, we have developed a high throughput fabrication method based on the femtosecond laser filament direct writing. The ability of fabricating large-scale THz elements with high precision and fast speed has been demonstrated by fabricating 100 × 100 mm2 spiral zone plates (SZPs), which can convert the Gaussian THz beam into vortex beam. The performance of the obtained THz vortex beam is in good agreement with the theoretical predictions. The fabrication method reported here has promising applications in fabricating various kinds of THz elements on substrates with both flat and curved surfaces.
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Affiliation(s)
- Zhi Zhang
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Zijie Dai
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Yunfei Wang
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Chunyue Chu
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Qiang Su
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Olga Kosareva
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China.,International Laser Center, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Nan Zhang
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China.
| | - Lie Lin
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Weiwei Liu
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China.
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Miyamoto K, Sano K, Miyakawa T, Niinomi H, Toyoda K, Vallés A, Omatsu T. Generation of high-quality terahertz OAM mode based on soft-aperture difference frequency generation. OPTICS EXPRESS 2019; 27:31840-31849. [PMID: 31684408 DOI: 10.1364/oe.27.031840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/08/2019] [Indexed: 06/10/2023]
Abstract
We demonstrate the generation of high-quality tunable terahertz (THz) vortices in an eigenmode by employing soft-aperture difference frequency generation of vortex and Gaussian modes. The generated THz vortex output exhibits a high-quality orbital angular momentum (OAM) mode with a topological charge of ℓTHz = ±1 in a frequency range of 2-6 THz. The maximum average power of the THz vortex output obtained was ∼3.3 µW at 4 THz.
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11
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Ivanov M, Thiele I, Bergé L, Skupin S, Buožius D, Vaičaitis V. Intensity modulated terahertz vortex wave generation in air plasma by two-color femtosecond laser pulses. OPTICS LETTERS 2019; 44:3889-3892. [PMID: 31368994 DOI: 10.1364/ol.44.003889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/03/2019] [Indexed: 06/10/2023]
Abstract
We investigate the generation of broadband terahertz (THz) pulses with phase singularity from air plasmas created by fundamental and second harmonic laser pulses. We show that when the second harmonic beam carries a vortex charge, the THz beam acquires a vortex structure as well. A generic feature of this THz vortex is that the intensity is modulated along the azimuthal angle, which can be attributed to the spatially varying relative phase difference between the two pump harmonics. Fully space- and time-resolved numerical simulations reveal that transverse instabilities of the pump further affect the emitted THz field along nonlinear propagation, which may produce additional singularities resulting in a rich vortex structure. The predicted intensity modulation is experimentally demonstrated with a thermal camera, in excellent agreement with simulation results. The presence of phase singularities in the experiment is revealed by astigmatic transformation of the beam using a cylindrical mirror.
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12
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Sobhani H, Dadar E. Terahertz vortex generation methods in rippled and vortex plasmas. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2019; 36:1187-1196. [PMID: 31503957 DOI: 10.1364/josaa.36.001187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/13/2019] [Indexed: 06/10/2023]
Abstract
Terahertz vortices have strong potential for many applications such as imaging and sensing in medicine, biomedical engineering, rotations of molecules, quantum condensation, optical tweezers, manipulation of electron beams, and communications. However, owing to recent developments, there has been less research about vortex generation in the terahertz domain. Due to the damaging limit and low conversion efficiency, a few schemes to generate terahertz vortices based on plasma have recently been reported. Generally, to excite the helicity of the terahertz vortices, two scenarios have been reported: one is transferring the orbital angular momentum from the plasma vortex to the emitted terahertz radiation, and the other is exciting the helicity of the terahertz vortices using twisted input lasers. This paper is a review of recent studies on terahertz vortex generation based on the rippled and vortex plasma substrata.
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Sirenko AA, Marsik P, Bernhard C, Stanislavchuk TN, Kiryukhin V, Cheong SW. Terahertz Vortex Beam as a Spectroscopic Probe of Magnetic Excitations. PHYSICAL REVIEW LETTERS 2019; 122:237401. [PMID: 31298919 DOI: 10.1103/physrevlett.122.237401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Indexed: 06/10/2023]
Abstract
Circularly polarized light with spin angular momentum is one of the most valuable probes of magnetism. We demonstrate that light beams with orbital angular momentum (OAM), or vortex beams, can also couple to magnetism exhibiting dichroisms in a magnetized medium. Resonant optical absorption in a ferrimagnetic crystal depends strongly on both the handedness of the vortex and the direction of the beam propagation with respect to the sample magnetization. This effect exceeds the conventional dichroism for circularly polarized light. Our results demonstrate the high potential of the vortex beams with OAM as a new spectroscopic probe of magnetism in matter.
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Affiliation(s)
- A A Sirenko
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - P Marsik
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - C Bernhard
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - T N Stanislavchuk
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - V Kiryukhin
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - S-W Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
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14
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Lin Q, Zheng S, Song Q, Zeng X, Cai Y, Li Y, Chen Z, Zha L, Pan X, Xu S. Generation of terahertz vortex pulses without any need of manipulation in the terahertz region. OPTICS LETTERS 2019; 44:887-890. [PMID: 30768012 DOI: 10.1364/ol.44.000887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 12/24/2018] [Indexed: 06/09/2023]
Abstract
Converting a Gaussian mode to a vortex beam is much more inconvenient in the terahertz (THz) region than in the near-infrared (NIR) region due to underdevelopment of THz components and strong THz diffraction. This Letter reports the direct generation of THz vortex pulses by optical difference-frequency between two NIR chirped pulses with different topological charges (TCs). By designing a passive and transmissive device for a collinear NIR pulse pair with conjugated TCs, we have experimentally obtained stable THz vortex pulses with a TC value of 2 or -2. The process needs no THz components and so is flexible to be realized and has promising applications in the THz field.
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15
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Zhao G, Savini G, Yu Y, Li S, Zhang J, Ade P. A dual-port THz Time Domain Spectroscopy System optimized for recovery of a sample's Jones matrix. Sci Rep 2019; 9:2099. [PMID: 30765838 PMCID: PMC6375982 DOI: 10.1038/s41598-019-39322-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/10/2019] [Indexed: 11/10/2022] Open
Abstract
We describe the design, build and characterization of a novel two-output port configuration for a THz-Time Domain Spectroscopy (TDS) system. By introducing a tilted THz ultra-broadband polarizer, we split the THz beam in two orthogonal polarization detector branches. The probe laser is similarly split (with an optical polarizer) replicating the detection chain to obtain two independent orthogonal polarization detection units. We describe the system's performance highlighting some of the advantages of this system in one of its two modes of operation: optimized polarimetry for Jones matrix measurements. A bi-refringent sapphire standard was measured to confirm its capabilities and assess the performance of the system showing good agreement with existing literature data.
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Affiliation(s)
- Guozhong Zhao
- Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing, China.,Department of Physics, Capital Normal University, Beijing, China
| | - Giorgio Savini
- Physics and Astronomy Department, University College London, London, WC1E 6BT, UK.
| | - Yang Yu
- Department of Physics, Capital Normal University, Beijing, China
| | - Shuai Li
- Department of Physics, Capital Normal University, Beijing, China
| | - Jin Zhang
- School of Computing and Information Science, Anglia Ruskin University, Cambridge, CB1 1PT, UK
| | - Peter Ade
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, Wales, UK
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Kulya M, Semenova V, Gorodetsky A, Bespalov VG, Petrov NV. Spatio-temporal and spatiospectral metrology of terahertz broadband uniformly topologically charged vortex beams. APPLIED OPTICS 2019; 58:A90-A100. [PMID: 30873965 DOI: 10.1364/ao.58.000a90] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 11/10/2018] [Indexed: 06/09/2023]
Abstract
A comprehensive characterization of the diffraction properties of terahertz (THz) pulsed broadband vortex beams consisting of several electromagnetic field oscillations requires state-of-the-art techniques for studying the evolution of a wavefront as it propagates. For this purpose, we have applied the capabilities offered by THz pulse time domain holography. Accurate metrological study of pulsed single-period THz field propagation allowed us to reveal the spatio-temporal and spatiospectral couplings in broadband uniformly topologically charged vortex beams. Here, we reveal dynamics of such beam propagation in a free space as well as in the experiment with edge diffraction with 50% blocking of the beam focal waist. In this study, we compare the dynamics of freely propagating and edge-diffracted THz vortex. Despite the fact that in the amplitude representation one can observe the emergence of strong asymmetry, analysis of the spectral trajectory of the singular point at some distance from the obstacle and the visualization of phase distribution for individual spectral components testify to the conservation of transverse energy circulation. Similar to the edge diffraction of monochromatic optical vortices, it can be interpreted as self-reconstruction of vortex properties. The given term has not previously been used for the case of pulsed broadband THz beams, to the best of our knowledge.
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17
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Wu Z, Wang X, Sun W, Feng S, Han P, Ye J, Yu Y, Zhang Y. Vectorial diffraction properties of THz vortex Bessel beams. OPTICS EXPRESS 2018; 26:1506-1520. [PMID: 29402024 DOI: 10.1364/oe.26.001506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/09/2018] [Indexed: 06/07/2023]
Abstract
A vortex Bessel beam combines the merits of an optical vortex and a Bessel beam, including a spiral wave front and a non-diffractive feature, which has immense application potentials in optical trapping, optical fabrication, optical communications, and so on. Here, linearly and circularly polarized vortex Bessel beams in the terahertz (THz) frequency range are generated by utilizing a THz quarter wave plate, a spiral phase plate, and Teflon axicons with different opening angles. Taking advantage of a THz focal-plane imaging system, vectorial diffraction properties of the THz vortex Bessel beams are comprehensively characterized and discussed, including the transverse (Ex, Ey) and longitudinal (Ez) polarization components. The experimental phenomena are accurately simulated by adopting the vectorial Rayleigh diffraction integral. By varying the opening angle of the axicon, the characteristic parameters of these THz vortex Bessel beams are exhibited and compared, including the light spot size, the diffraction-free range, and the phase evolution process. This work provides the precise experimental and theoretical bases for the comprehension and application of a THz vortex Bessel beam.
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Generating, Separating and Polarizing Terahertz Vortex Beams via Liquid Crystals with Gradient-Rotation Directors. CRYSTALS 2017. [DOI: 10.3390/cryst7100314] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Vortex beams have received considerable research interests both in optical and millimeter-wave domain since its potential to be utilized in the wireless communications and novel imaging systems. Many well-known optical beams have been demonstrated to carry orbital angular momentum (OAM), such as Laguerre-Gaussian beams and high-order Bessel beams. Recently, the radially symmetric Airy beams that exhibit an abruptly autofocusing feature are also demonstrated to be capable of carrying OAM in the optical domain. However, due to the lack of efficient devices to manipulate terahertz (THz) beams, it could be a challenge to demonstrate the radially symmetric Airy beams in the THz domain. Here we demonstrate the THz circular Airy vortex beams (CAVBs) with a 0.3-THz continuous wave through 3D printing technology. Assisted by the rapidly 3D-printed phase plates, individual OAM states with topological charge l ranging from l = 0 to l = 3 and a multiplexed OAM state are successfully imposed into the radially symmetric Airy beams. We both numerically and experimentally investigate the propagation dynamics of the generated THz CAVBs, and the simulations agree well with the observations.
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Ge S, Chen P, Shen Z, Sun W, Wang X, Hu W, Zhang Y, Lu Y. Terahertz vortex beam generator based on a photopatterned large birefringence liquid crystal. OPTICS EXPRESS 2017; 25:12349-12356. [PMID: 28786591 DOI: 10.1364/oe.25.012349] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/10/2017] [Indexed: 06/07/2023]
Abstract
A terahertz (THz) q-plate is proposed and demonstrated to generate THz vortex beams. It is composed of a large birefringence liquid crystal (LC) with spatially-varying director distribution sandwiched by two pieces of fused silica glass. A polarization-sensitive alignment agent is photopatterned to carry out the specific LC director distribution. THz vortex beams with different topological charges are characterized with a THz digital holographic imaging system. The intensity and phase distributions consistent with theoretical analyses are obtained. Besides, an eight-lobed intensity distribution is observed corresponding to the vertical polarization component of a cylindrical vector beam. This work may inspire novel THz applications.
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Li H, Ren G, Zhu B, Gao Y, Yin B, Wang J, Jian S. Guiding terahertz orbital angular momentum beams in multimode Kagome hollow-core fibers. OPTICS LETTERS 2017; 42:179-182. [PMID: 28081067 DOI: 10.1364/ol.42.000179] [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 explore terahertz (THz) orbital angular momentum (OAM) modes supported in multimode Kagome hollow-core fibers. Numerical models are adopted to characterize the effective indices and confinement losses of vector modes over 0.2-0.9 THz, where two low-loss transmission windows are observed. Linearly combining the vector modes, THz OAM states can be generated. Covering a broad bandwidth of 0.25 THz, the purity values of OAM modes are beyond 0.9. Using numerical simulations, the hollow-core THz fibers with one and two rings of Kagome structures are also comparably investigated. We reveal that the OAM purity is dependent upon the confinement performance of THz fiber.
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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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Choporova Y, Knyazev B, Osintseva N, Pavelyev V, Volodkin B. Terahertz Bessel beams with orbital angular momentum: diffraction and interference. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201714905003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Miyamoto K, Kang BJ, Kim WT, Sasaki Y, Niinomi H, Suizu K, Rotermund F, Omatsu T. Highly intense monocycle terahertz vortex generation by utilizing a Tsurupica spiral phase plate. Sci Rep 2016; 6:38880. [PMID: 27966595 PMCID: PMC5155293 DOI: 10.1038/srep38880] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/15/2016] [Indexed: 11/28/2022] Open
Abstract
Optical vortex, possessing an annular intensity profile and an orbital angular momentum (characterized by an integer termed a topological charge) associated with a helical wavefront, has attracted great attention for diverse applications due to its unique properties. In particular for terahertz (THz) frequency range, several approaches for THz vortex generation, including molded phase plates consisting of metal slit antennas, achromatic polarization elements and binary-diffractive optical elements, have been recently proposed, however, they are typically designed for a specific frequency. Here, we demonstrate highly intense broadband monocycle vortex generation near 0.6 THz by utilizing a polymeric Tsurupica spiral phase plate in combination with tilted-pulse-front optical rectification in a prism-cut LiNbO3 crystal. A maximum peak power of 2.3 MW was obtained for THz vortex output with an expected topological charge of 1.15. Furthermore, we applied the highly intense THz vortex beam for studying unique nonlinear behaviors in bilayer graphene towards the development of nonlinear super-resolution THz microscopy and imaging system.
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Affiliation(s)
- Katsuhiko Miyamoto
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Bong Joo Kang
- Department of Physics and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea
| | - Won Tae Kim
- Department of Physics and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea
| | - Yuta Sasaki
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hiromasa Niinomi
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Koji Suizu
- Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Fabian Rotermund
- Department of Physics and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea.,Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
| | - Takashige Omatsu
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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Knyazev BA, Choporova YY, Mitkov MS, Pavelyev VS, Volodkin BO. Generation of Terahertz Surface Plasmon Polaritons Using Nondiffractive Bessel Beams with Orbital Angular Momentum. PHYSICAL REVIEW LETTERS 2015; 115:163901. [PMID: 26550877 DOI: 10.1103/physrevlett.115.163901] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Indexed: 06/05/2023]
Abstract
Bessel vortex beams with topological charges of l=±1 and l=±2 were produced in the terahertz spectral range from a free electron laser Gaussian beam (λ=141 μm) transformed using silicon binary diffractive optical elements. The spatial characteristics of the beams were obtained using a microbolometer array. A radius to path length ratio of 1:100 was achieved for nondiffractive beams with the average power of 30 W. Surface plasmon polaritons (SPPs) on gold-zinc-sulphide-air interfaces were generated due to diffraction of vortex beams on a sample edge. A new effect, a dependence of the efficiency of SPP generation on the direction of the azimuthal component of incident-radiation Poynting vector, was revealed.
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Affiliation(s)
- B A Knyazev
- Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Yu Yu Choporova
- Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - M S Mitkov
- Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
- Novosibirsk State Technical University, 630073 Novosibirsk, Russia
| | - V S Pavelyev
- Samara State Aerospace University, 443086 Samara, Russia
- Image Processing Systems Institute RAS, 443001 Samara, Russia
| | - B O Volodkin
- Samara State Aerospace University, 443086 Samara, Russia
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Determination of the polarization states of an arbitrary polarized terahertz beam: vectorial vortex analysis. Sci Rep 2015; 5:9416. [PMID: 25799965 PMCID: PMC4371186 DOI: 10.1038/srep09416] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/25/2015] [Indexed: 11/09/2022] Open
Abstract
Vectorial vortex analysis is used to determine the polarization states of an arbitrarily polarized terahertz (0.1-1.6 THz) beam using THz achromatic axially symmetric wave (TAS) plates, which have a phase retardance of Δ = 163° and are made of polytetrafluorethylene. Polarized THz beams are converted into THz vectorial vortex beams with no spatial or wavelength dispersion, and the unknown polarization states of the incident THz beams are reconstructed. The polarization determination is also demonstrated at frequencies of 0.16 and 0.36 THz. The results obtained by solving the inverse source problem agree with the values used in the experiments. This vectorial vortex analysis enables a determination of the polarization states of the incident THz beam from the THz image. The polarization states of the beams are estimated after they pass through the TAS plates. The results validate this new approach to polarization detection for intense THz sources. It could find application in such cutting edge areas of physics as nonlinear THz photonics and plasmon excitation, because TAS plates not only instantaneously elucidate the polarization of an enclosed THz beam but can also passively control THz vectorial vortex beams.
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