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Frontiers of Optoelectronics

Front. Optoelectron.    2019, Vol. 12 Issue (2) : 117-147
Terahertz wave generation from ring-Airy beam induced plasmas and remote detection by terahertz-radiation-enhanced-emission-of-fluorescence: a review
Kang LIU1, Pingjie HUANG2, Xi-Cheng ZHANG1,3()
1. The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
2. State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310027, China
3. The Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100037, China
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With the increasing demands for remote spectroscopy in many fields ranging from homeland security to environmental monitoring, terahertz (THz) spectroscopy has drawn a significant amount of attention because of its capability to acquire chemical spectral signatures non-invasively. However, advanced THz remote sensing techniques are obstructed by quite a few factors, such as THz waves being strongly absorbed by water vapor in the ambient air, difficulty to generate intense broadband coherent THz source remotely, and hard to transmit THz waveform information remotely without losing the signal to noise ratio, etc. In this review, after introducing different THz air-photonics techniques to overcome the difficulties of THz remote sensing, we focus mainly on theoretical and experimental methods to improve THz generation and detection performance for the purpose of remote sensing through tailoring the generation and detection media, air-plasma.

For the THz generation part, auto-focusing ring-Airy beam was introduced to enhance the THz wave generation yield from two-color laser induced air plasma. By artificially modulated exotic wave packets, it is exhibited that abruptly auto-focusing beam induced air-plasma can give an up to 5.3-time-enhanced THz wave pulse energy compared to normal Gaussian beam induced plasma under the same conditions. At the same time, a red shift on the THz emission spectrum is also observed. A simulation using an interference model to qualitatively describe these behaviors has be developed.

For the THz detection part, the results of THz remote sensing at 30 m using THz-radiation-enhanced-emission-of-fluorescence (THz-REEF) technique are demonstrated, which greatly improved from the 10 m demonstration last reported. The THz-REEF technique in the counter-propagation geometry was explored, which is proved to be more practical for stand-off detections than co-propagation geometry. We found that in the counter-propagating geometry the maximum amplitude of the REEF signal is comparable to that in the co-propagating case, whereas the time resolved REEF trace significantly changes. By performing the study with different plasmas, we observed that in the counter-propagating geometry the shape of the REEF trace depends strongly on the plasma length and electron density. A new theoretical model suggesting that the densest volume of the plasma does not contribute to the fluorescence enhancement is proposed to reproduce the experimental measurements.

Our results further the understanding of the THz-plasma interaction and highlight the potential of THz-REEF technique in the plasma detection applications.

Keywords ultrafast terahertz (THz) techniques      THz air-photonics      ring-Airy beams      THz-radiation-enhanced-emission-of-fluorescence (THz-REEF) of air-plasma in co-propagation geometry      THz-REEF of air-plasma in counter-propagation geometry     
Corresponding Authors: Xi-Cheng ZHANG   
Just Accepted Date: 29 November 2018   Online First Date: 22 January 2019    Issue Date: 03 July 2019
 Cite this article:   
Kang LIU,Pingjie HUANG,Xi-Cheng ZHANG. Terahertz wave generation from ring-Airy beam induced plasmas and remote detection by terahertz-radiation-enhanced-emission-of-fluorescence: a review[J]. Front. Optoelectron., 2019, 12(2): 117-147.
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Kang LIU
Pingjie HUANG
Xi-Cheng ZHANG
Fig.1  Experimental setup for measuring the THz radiation pattern from a laser-induced filamentation (Reprinted from Ref. [46])
Fig.2  Schematic demonstration of experimental setup for THz generation from two-color laser induced air plasma. An intense femto-second laser beam ω is focused by a lens to generate plasma in the air, β-BBO is used to generate 2 ω
Fig.3  (a) Inside the dashed line is the in-line PC (phase compensator). (b) Schematic illustration of the PC incorporated with a wedge pair: DM used to separate or recombine ω and 2ω beams; HWP used to control the polarization of the 2ω beam. DWP, dual-wavelength waveplate; BP, birefringent plate (α-BBO); QW, quartz wedges; Fs, femtosecond; HR, highly reflect; DM, dichroic mirror (Reprinted from Ref. [53] ©2011 IEEE)
Fig.4  Schematic of THz emission from a long, two-color laser-induced filament. The phase difference between 800 nm (dashed red curves) and 400 nm (solid blue curves) pulses along the filament results in a periodic oscillation of microscopic current amplitude and polarity. The resulting far-field THz radiation is determined by interference between the waves emitted from the local sources along the filament. P1, P2 and P3 are respectively the optical path along the different directions as shown in the figure, θ is the angle between P3 and P1 (Reprinted from Ref. [57])
Fig.5  (a) Basic concept of THz-ABCD: electrodes are placed at the geometric focus of collinearly focused THz and optical probe beams with a variable time delay. Second harmonic light is induced from the THz field and the local bias field Ebias. Modulating Ebias allows for heterodyne detection for enhanced sensitivity. (b) Measured second harmonic intensity vs third order nonlinear susceptibility χ(3). All χ (3) are normalized with respect to nitrogen (Reprinted from Ref. [66] ©2011 IEEE)
Fig.6  Envisioned scheme for THz stand-off generation and detection. Two dual-color pulses are focused close to the target under investigation creating a plasma emitter and a plasma sensor. Inset shows an absorbance spectrum of 4A-DNT retrieved through THz-REEF (Reprinted from Ref. [71])
Fig.7  (a) Experimental set-up for observing the ring-Airy beam induced air plasma; (b) fluorescence false color images of ring-Airy beam plasmas (top 5) with pulse energy from 0.25 to 0.65 mJ, and Gaussian beam plasma (bottom) with pulse energy 0.65 mJ. The Gaussian plasma image intensity has been reduced 25 times to reach similar visibility of the ring-Airy beam plasmas
Fig.8  Experimental set-up. SLM: spatial light modulator, OD: opaque disk, on a transparent glass slide, L: lens, PM: parabolic mirror, M: mirror. Inset: Schematic comparison between the radial intensity distribution of the ring-Airy and the Gaussian beam; zoom-in on the beam area prior and post to the glass slide: case 1 is when using the Gaussian beam, the glass slide is shifted so the OD is removed from the beam path, case 2 is when using the ring-Airy beam, the OD is moved back into the center of the beam to block the unwanted part
Fig.9  (a) Typical THz waveform generated from the ring-Airy beam induced plasma pumped with a pulse energy of 0.65 mJ; (b) corresponding spectrum
Fig.10  THz emission peak amplitude versus the b-BBO distance from the focus. Blue dots: experimental data; blue solid curve: FWM model fitting result; black dashed curve: nonlinear fitting envelope taking into account the SHG efficiency change as the BBO is moving toward the focus; the insets show two sample THz waveforms having opposite polarities
Fig.11  Emitted THz wave peak amplitude as a function of total pump pulse energy (800 and 400 nm). Red dots: experimental data from ring-Airy beam; red dashed line: fitting of the ring-Airy data with the FWM model. The error bars are the measurements standard deviation of each point
Fig.12  (a) Fluorescence image comparison between an ring-Airy beam plasma and a Gaussian plasma (intensity reduced by 20 times), both generated with pump pulse energy 0.5 mJ; (b) measured THz waveforms and (c) their corresponding normalized spectra generated by the two plasmas in (a)
Fig.13  Comparison between THz emission peak amplitudes from ring-Airy beam and Gaussian beam versus different pump pulse energy
Fig.14  Schematic representation of two-color filament THz generation interference model (Reprinted from Ref. [104])
Fig.15  (a) Normalized simulations of THz radiation spectrums without and (b) with the 3-mm-thick ZnTe detection bandwidth limitation; the inset in (a) is the enlarged version of the blue area (0−4 THz). Red solid curves: emission from ring-Airy plasma; black dashed curves: emission from Gaussian plasma
Fig.16   Spectrum of air interacting with a 220 fs laser pulse. The lines marked by 1 are assigned to the first negative band system of N 2+( B3 u+ X 2 g+ transition) and those marked by 2 are assigned to the second positive band systemof N2( C3ΠuB3 Πgtransition) respectively. In the transitions (v–v′), v and v′ denote the vibrational levels of upper and lower electronic states, respectively (Reprinted from Ref. [105])
Fig.17  (a) Schematics of the interaction between the THz wave and laser induced plasma. (b) Measured fluorescence spectra versus THz field as td = −1 ps. Major fluorescence lines are labeled. (c) Measured quadratic THz field dependence of 357 nm fluorescence emission line as td = −1 ps. Inset: Theisotropic emission pattern of THz-REEF (Reprinted from Ref. [60])
Fig.18  (a) Time-resolved THz-REEF ΔFL (t d) and THz field ETHz(td). (b) Time-resolved ΔFL( td ), ETHz(td), dΔ FL (t d)/ dt d, and ETHz2( td) on therising edge in the expanded scale of (a). All curves are normalized and offset forclarity (Reprinted from Ref. [60])
Fig.19  Schematic figure of THz-REEF remote sensing experimental setup. DWP: dual wave plate; OPM: off-axis parabolic mirror; PMT: photo multiplier tube detector
Fig.20  Terahertz wave assisted electron impact ionization of high-lying states in plasma. (a) High-lying states can be ionized by a series of collisions with energetic electrons; (b) interaction between the terahertz pulse and the asymmetric photoelectron velocity distributions generated by two-color field ionization (Reprinted from Ref. [61])
Fig.21  Measured time-dependent REEF at a relative optical phase change of Δ φω, 2ω=±mπ/2. The terahertz wave enhanced fluorescence shows significantdependence on the initial electron velocity distribution, which is determined by Δ φω ,2ω (Reprinted from Ref. [61])
Fig.22  Typical two-color THz-REEF signal. Blue and green: two THz-REEF traces with different relative phase Δφω,2ω. Red: the difference between blue andgreen curves, that gives the measured THz waveform
Fig.23  THz waveforms measured by two-color THz-REEF technique at different detection distances, 0.1, 7, 14, 20, 30 m respectively
Fig.24  Depiction of the co-propagation and counter-propagation interaction geometries. (a) and (c) are showing the plasma fluorescence intensity enhancement as a function ofΔt in (a) co-propagating and (c) counter-propagating geometriesmeasured by PMT. Both curves are normalized to 1. (b) In co-propagating geometry the THz (blue) and the NIR (red) pulses travel in the same direction. (d) In counter-propagating geometry the THz and NIR pulses travel in opposite directions. Δtis the time delay between the two pulses. The special cases of Δt = t1, t2 in co-propagation or Δt=t 1 , t2 in counter-propagation are respectively denoted in (a,b) and (c,d)
Fig.25  Schematic demonstrations of plasmas of different lengths being generated by (a) 4 inch EFL, (b) 2 inch EFL, and (c) 1 inch EFL plano-convex lenses. (d) Time-resolved counter-propagation THz-REEF measurements of the plasmas generated in (a)−(c) cases
Fig.26  (a) Time-resolved counter-propagation THz-REEF intensity for 2 inch EFL lens case (solid red) and its derivative (solid black). The black dots represent the data sampling rate used for the derivative in order to reduce the noise of the result. The curves are offset for clarity. (b) Derivative of REEF signal curve (solid black) is compared to the square of the experimental THz waveform measured with electro-optic sampling (solid blue)
Fig.27  Time-resolved counter-propagation THz-REEF measurements of a micro-plasma with different THz pulse peak field strengths. The plasma is generated by a 2 inch EFL lens
Fig.28  Micro-plasma fluorescence emission spectra with different values of plasma excitation laser pulse energy. Red is when no THz pulse is applied and blue is when a THz pulse with peak field of 90 kV/cm is applied. The microplasmas are obtained with a 1 inch EFL plano-convex lens
Fig.29  Time-resolved counter-propagation two color THz-REEF measurements with different phases Δϕ between ωand 2ωpulses. The plasma is generated with (a) 4 inch EFL lens and (b) 2 inch EFL lens. (c) Plasma fluorescence intensity modulation as a function of the relative phase Δϕ
Fig.30  Experimental (solid line) and numerical fitted (dashed line) time resolved counter-propagation THz-REEF intensity for the following focusing conditions: (a) 2 inch EFL lens; (c) 1 inch EFL lens; in (b), (d), the solid shaded areas represent the integration of the plasma fluorescence intensity along the radial dimension as measured with the iCCD camera, and the dashed lines are the numerically evaluated plasma effective electron densities producing the dashed curves plotted in (a) and (c)
1 X C Zhang, J Xu. Introduction to THz Wave Photonics. New York: Springer, 2010
2 X C Zhang. Teaching note, 2013
3 D J Fixsen, E S Cheng, J M Gales, J C Mather, R A Shafer, E L Wright. The cosmic microwave background spectrum from the full cobefiras data set. Astrophysical Journal, 1996, 473(2): 576–587
4 D T Leisawitz, W C Danchi, M J DiPirro, L D Feinberg, D Y Gezari, M Hagopian, W D Langer, J C Mather, S H Moseley, M Shao, R F Silverberg, J G Staquhn, M R Swain, H W Yorke, X L Zhang. Scientific motivation and technology requirements for the SPIRIT and SPECS far-infrared/submillimeter space interferometers. In: Proceedings of SPIE 4013, UV, Optical, and IR Space Telescopes and Instruments. International Society for Optics and Photonics, 2000, 36–47
5 T G Phillips, J Keene. Submillimeter astronomy (heterodyne spectroscopy). Proceedings of the IEEE, 1992, 80(11): 1662–1678
6 A K Majumdar. Advanced Free Space Optics (FSO): A Systems Approach. New York: Springer, 2014
7 H B Liu, Y Chen, G J Bastiaans, X C Zhang. Detection and identification of explosive RDX by THz diffuse reflection spectroscopy. Optics Express, 2006, 14(1): 415–423 pmid: 19503355
8 M R Leahy-Hoppa, M J Fitch, X Zheng, L M Hayden, R Osiander. Wideband terahertz spectroscopy of explosives. Chemical Physics Letters, 2007, 434(4–6): 227–230
9 A G Davies, A D Burnett, W Fan, E H Linfield, J E Cunningham. Terahertz spectroscopy of explosives and drugs. Materials Today, 2008, 11(3): 18–26
10 J F Federici, B Schulkin, F Huang, D Gary, R Barat, F Oliveira, D Zimdars. Thz imaging and sensing for security applications—explosives, weapons and drugs. Semiconductor Science and Technology, 2005, 20(7): S266–S280
11 M Tonouchi. Cutting-edge terahertz technology. Nature Photonics, 2007, 1(2): 97–105
12 C A Roobottom, G Mitchell, G Morgan-Hughes. Radiation-reduction strategies in cardiac computed tomographic angiography. Clinical Radiology, 2010, 65(11): 859–867 pmid: 20933639
13 B S Alexandrov, V Gelev, A R Bishop, A Usheva, K O Rasmussen. DNA breathing dynamics in the presence of a terahertz field. Physics Letters A, 2010, 374(10): 1214–1217 pmid: 20174451
14 P H Siegel, V Pikov. Impact of low intensity millimetre waves on cell functions. Electronics Letters, 2010, 46(26): 70–72
15 J Chen, Y Chen, H Zhao, G J Bastiaans, X C Zhang. Absorption coefficients of selected explosives and related compounds in the range of 0.1-2.8 THz. Optics Express, 2007, 15(19): 12060–12067 pmid: 19547570
16 X C Zhang, A Shkurinov, Y Zhang. Extreme terahertz science. Nature Photonics, 2017, 11(1): 16–18
17 Y S Lee. Principles of Terahertz Science and Technology. New York: Springer, 2009
18 D H Auston. Picosecond optoelectronic switching and gating in silicon. Applied Physics Letters, 1975, 26(3): 101–103
19 M Tani, S Matsuura, K Sakai, S Nakashima. Emission characteristics of photoconductive antennas based on low-temperature-grown GaAs and semi-insulating GaAs. Applied Optics, 1997, 36(30): 7853–7859 pmid: 18264312
20 D H Auston, K P Cheung, P R Smith. Picosecond photoconducting hertzian dipoles. Applied Physics Letters, 1984, 45(3): 284–286
21 X Ropagnol, M Khorasaninejad, M Raeiszadeh, S Safavi-Naeini, M Bouvier, C Y Côté, A Laramée, M Reid, M A Gauthier, T Ozaki. Intense THz Pulses with large ponderomotive potential generated from large aperture photoconductive antennas. Optics Express, 2016, 24(11): 11299–11311 pmid: 27410061
22 H A Hafez, X Chai, A Ibrahim, S Mondal, D Férachou, X Ropagnol, T Ozaki. Intense terahertz radiation and their applications. Journal of Optics, 2016, 18(9): 093004
23 R W Boyd. Nonlinear Optics. Oxford: Elsevier, 2008
24 G Kh Kitaeva. Terahertz generation by means of optical lasers. Laser Physics Letters, 2008, 5(8): 559–576
25 K Reimann. Table-top sources of ultrashort Thz pulses. Reports on Progress in Physics, 2007, 70(10): 1597–1632
26 A Rice, Y Jin, X F Ma, X C Zhang, D Bliss, J Larkin, M Alexander. Terahertz optical rectification from<110>zinc-blende crystals. Applied Physics Letters, 1994, 64(11): 1324–1326
27 K H Yang, P L Richards, Y R Shen. Generation of far-infrared radiation by picosecond light pulses in LiNbO3. Applied Physics Letters, 1971, 19(9): 320–323
28 J Hebling, G Almasi, I Kozma, J Kuhl. Velocity matching by pulse front tilting for large area THz-pulse generation. Optics Express, 2002, 10(21): 1161–1166 pmid: 19451975
29 J Hebling, K L Yeh, M C Hoffmann, B Bartal, K A Nelson. Generation of high-power terahertz pulses by tilted pulse-front excitation and their application possibilities. Journal of the Optical Society of America B, Optical Physics, 2008, 25(7): B6–B19
30 J A Fülöp, L Pálfalvi, S Klingebiel, G Almási, F Krausz, S Karsch, J Hebling. Generation of sub-mJ terahertz pulses by optical rectification. Optics Letters, 2012, 37(4): 557–559 pmid: 22344105
31 H Hirori, A Doi, F Blanchard, K Tanaka. Single-cycle terahertz pulses with amplitudes exceeding 1 mV/cm generated by optical rectification in LiNbO3. Applied Physics Letters, 2011, 98(9): 091106
32 X C Zhang, X F Ma, Y Jin, T M Lu, E P Boden, P D Phelps, K R Stewart, C P Yakymyshyn. Terahertz optical rectification from a nonlinear organic crystal. Applied Physics Letters, 1992, 61(26): 3080–3082
33 C P Hauri, C Ruchert, C Vicario, F Ardana. Strong-field single-cycle THz pulses generated in an organic crystal. Applied Physics Letters, 2011, 99(16): 161116
34 M Shalaby, C P Hauri. Demonstration of a low-frequency three-dimensional terahertz bullet with extreme brightness. Nature Communications, 2015, 6(1): 5976 pmid: 25591665
35 H Hamster, A Sullivan, S Gordon, W White, R W Falcone. Subpicosecond, electromagnetic pulses from intense laser-plasma interaction. Physical Review Letters, 1993, 71(17): 2725–2728 pmid: 10054760
36 D J Cook, R M Hochstrasser. Intense terahertz pulses by four-wave rectification in air. Optics Letters, 2000, 25(16): 1210–1212 pmid: 18066171
37 J Dai, B Clough, I C Ho, X Lu, J Liu, X C Zhang. Recent progresses in terahertz wave air photonics. IEEE Transactions on Terahertz Science and Technology, 2011, 1(1): 274–281
38 K Y Kim, A J Taylor, J H Glownia, G Rodriguez. Coherent control of terahertz supercontinuum generation in ultrafast laser–gas interactions. Nature Photonics, 2008, 2(10): 605–609
39 Q Wu, X C Zhang. Free-space electro-optic sampling of terahertz beams. Applied Physics Letters, 1995, 67(24): 3523–3525
40 M C Nuss, D H Auston, F Capasso. Direct subpicosecond measurement of carrier mobility of photoexcited electrons in gallium arsenide. Physical Review Letters, 1987, 58(22): 2355–2358 pmid: 10034724
41 M van Exter, C Fattinger, D Grischkowsky. Terahertz time-domain spectroscopy of water vapor. Optics Letters, 1989, 14(20): 1128–1130 pmid: 19753077
42 G J Morales, Y C Lee. Ponderomotive-force effects in a nonuniform plasma. Physical Review Letters, 1974, 33(17): 1016–1019
43 K Liu, X C Buccheri F, Zhang. Thz science and technology of micro-plasma. Physics (Chinese Wuli), 2015, 44: 497–502
44 H Hamster, A Sullivan, S Gordon, R W Falcone. Short-pulse terahertz radiation from high-intensity-laser-produced plasmas. Physical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 1994, 49(1): 671–677 pmid: 9961261
45 T Löffler, F Jacob, H G Roskos. Generation of terahertz pulses by photoionization of electrically biased air. Applied Physics Letters, 2000, 77(3): 453–455
46 C D’Amico, A Houard, M Franco, B Prade, A Mysyrowicz, A Couairon, V T Tikhonchuk. Conical forward THz emission from femtosecond-laser-beam filamentation in air. Physical Review Letters, 2007, 98(23): 235002 pmid: 17677911
47 C D Amico, A Houard, S Akturk, Y Liu, J Le Bloas, M Franco, B Prade, A Couairon, V T Tikhonchuk, A Mysyrowicz. Forward THz radiation emission by femtosecond filamentation in gases: theory and experiment. New Journal of Physics, 2008, 10(1): 013015
48 F Buccheri, X C Zhang. Terahertz emission from laser induced microplasma in ambient air. Optica, 2015, 2(4): 366–369
49 X Xie, J Dai, X C Zhang. Coherent control of THz wave generation in ambient air. Physical Review Letters, 2006, 96(7): 075005 pmid: 16606102
50 M Kress, T Löffler, S Eden, M Thomson, H G Roskos. Terahertz-pulse generation by photoionization of air with laser pulses composed of both fundamental and second-harmonic waves. Optics Letters, 2004, 29(10): 1120–1122 pmid: 15182005
51 B Clough, J M Dai, X C Zhang. Laser air photonics: covering the “terahertz gap” and beyond. Zhongguo Wuli Xuekan, 2014, 52(1): 416–430
52 Y Chen, M Yamaguchi, M Wang, X C Zhang. Terahertz pulse generation from noble gases. Applied Physics Letters, 2007, 91(25): 251116
53 J Dai, J Liu, X C Zhang. Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma. IEEE Journal of Selected Topics in Quantum Electronics, 2011, 17(1): 183–190
54 J Dai, N Karpowicz, X C Zhang. Coherent polarization control of terahertz waves generated from two-color laser-induced gas plasma. Physical Review Letters, 2009, 103(2): 023001 pmid: 19659200
55 K Y Kim, J H Glownia, A J Taylor, G Rodriguez. Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields. Optics Express, 2007, 15(8): 4577–4584 pmid: 19532704
56 N Karpowicz, X C Zhang. Coherent terahertz echo of tunnel ionization in gases. Physical Review Letters, 2009, 102(9): 093001 pmid: 19392516
57 Y S You, T I Oh, K Y Kim. Off-axis phase-matched terahertz emission from two-color laser-induced plasma filaments. Physical Review Letters, 2012, 109(18): 183902 pmid: 23215280
58 V Blank, M D Thomson, H G Roskos. Spatio-spectral characteristics of ultra-broadband THz emission from two-colour photo excited gas plasmas and their impact for nonlinear spectroscopy. New Journal of Physics, 2013, 15(7): 075023
59 J M Manceau, M Massaouti, S Tzortzakis. Strong terahertz emission enhancement via femtosecond laser filament concatenation in air. Optics Letters, 2010, 35(14): 2424–2426 pmid: 20634851
60 J Liu, X C Zhang. Terahertz-radiation-enhanced emission of fluorescence from gas plasma. Physical Review Letters, 2009, 103(23): 235002 pmid: 20366153
61 J Liu, J Dai, S L Chin, X C Zhang. Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases. Nature Photonics, 2010, 4(9): 627–631
62 B Clough, J Liu, X C Zhang. Laser-induced photoacoustics influenced by single-cycle terahertz radiation. Optics Letters, 2010, 35(21): 3544–3546 pmid: 21042344
63 D J Cook, J X Chen, E A Morlino, R M Hochstrasser. Terahertz field-induced second-harmonic generation measurements of liquid dynamics. Chemical Physics Letters, 1999, 309(3–4): 221–228
64 J Dai, X Xie, X C Zhang. Detection of broadband terahertz waves with a laser-induced plasma in gases. Physical Review Letters, 2006, 97(10): 103903 pmid: 17025819
65 N Karpowicz, J Dai, X Lu, Y Chen, M Yamaguchi, H Zhao, X C Zhang, L Zhang, C Zhang, M Price-Gallagher, C Fletcher, O Mamer, A Lesimple, K Johnson. Coherent heterodyne time-domain spectrometry covering the entire “terahertz gap”. Applied Physics Letters, 2008, 92(1): 011131
66 B Clough, J Dai, X C Zhang. Laser air photonics: beyond the terahertz gap. Materials Today, 2012, 15(1–2): 50–58
67 X Lu, N Karpowicz, Y Chen, X C Zhang. Systematic study of broadband terahertz gas sensor. Applied Physics Letters, 2008, 93(26): 261106
68 M Zalkovskij, C Zoffmann Bisgaard, A Novitsky, R Malureanu, D Savastru, A Popescu, P Uhd Jepsen, A V Lavrinenko. Ultrabroadband terahertz spectroscopy of chalcogenide glasses. Applied Physics Letters, 2012, 100(3): 031901
69 F D’Angelo, Z Mics, M Bonn, D Turchinovich. Ultra-broadband THz time-domain spectroscopy of common polymers using THz air photonics. Optics Express, 2014, 22(10): 12475–12485 pmid: 24921365
70 Y Yang, M Mandehgar, D R Grischkowsky. Broadband THz pulse transmission through the atmosphere. IEEE Transactions on Terahertz Science and Technology, 2011, 1(1): 264–273
71 X Sun, F Buccheri, J Dai, X C Zhang. Review of THz wave air photonics. In: Proceedings of SPIE 8562, Infrared, Millimeter-Wave, and Terahertz Technologies II. SPIE, 2012, 856202
72 B Clough, J Liu, X C Zhang. “All air-plasma” terahertz spectroscopy. Optics Letters, 2011, 36(13): 2399–2401 pmid: 21725424
73 M V Berry, N L Balazs. Nonspreading wave packets. American Journal of Physics, 1979, 47(3): 264–267
74 K Unnikrishnan, A R P Rau. Uniqueness of the Airy packet in quantum mechanics. American Journal of Physics, 1996, 64(8): 1034–1035
75 L I Schiff. Quantum Mechanics. Oxford: McGraw-Hill Education (India) Pvt Limited, 1968
76 J Durnin. Exact solutions for nondiffracting beams. I. The scalar theory. Journal of the Optical Society of America A, Optics and Image Science, 1987, 4(4): 651–654
77 J Durnin, J Miceli Jr, J H Eberly. Diffraction-free beams. Physical Review Letters, 1987, 58(15): 1499–1501 pmid: 10034453
78 D McGloin, K Dholakia. Bessel beams: diffraction in a new light. Contemporary Physics, 2005, 46(1): 15–28
79 J C Gutiérrez-Vega, M D Iturbe-Castillo, S Chávez-Cerda. Alternative formulation for invariant optical fields: Mathieu beams. Optics Letters, 2000, 25(20): 1493–1495 pmid: 18066256
80 M A Bandres, J C Gutiérrez-Vega. Ince-Gaussian beams. Optics Letters, 2004, 29(2): 144–146 pmid: 14743992
81 G A Siviloglou, D N Christodoulides. Accelerating finite energy Airy beams. Optics Letters, 2007, 32(8): 979–981 pmid: 17375174
82 G A Siviloglou, J Broky, A Dogariu, D N Christodoulides. Observation of accelerating Airy beams. Physical Review Letters, 2007, 99(21): 213901 pmid: 18233219
83 D Abdollahpour, S Suntsov, D G Papazoglou, S Tzortzakis. Spatiotemporal Airy light bullets in the linear and nonlinear regimes. Physical Review Letters, 2010, 105(25): 253901 pmid: 21231591
84 A Chong, W H Renninger, D N Christodoulides, F W Wise. Airy–Bessel wave packets as versatile linear light bullets. Nature Photonics, 2010, 4(2): 103–106
85 D G Papazoglou, N K Efremidis, D N Christodoulides, S Tzortzakis. Observation of abruptly auto focusing waves. Optics Letters, 2011, 6(10): 1842–1844
pmid: 21593909
86 N K Efremidis, D N Christodoulides. Abruptly autofocusing waves. Optics Letters, 2010, 35(23): 4045–4047 pmid: 21124607
87 D G Papazoglou. Personal communication, 2015
88 I Chremmos, N K Efremidis, D N Christodoulides. Pre-engineered abruptly autofocusing beams. Optics Letters, 2011, 36(10): 1890–1892 pmid: 21593925
89 K Liu, A D Koulouklidis, D G Papazoglou, S Tzortzakis, X C Zhang. Enhanced terahertz wave emission from air-plasma tailored by abruptly autofocusing laser beams. Optica, 2016, 3(6): 605–608
90 A D Koulouklidis, D G Papazoglou, V Y Fedorov, S Tzortzakis. Phase memory preserving harmonics from abruptly autofocusing beams. Physical Review Letters, 2017, 119(22): 223901
91 D G Papazoglou, V Y Fedorov, S Tzortzakis. Janus waves. Optics Letters, 2016, 41(20): 4656–4659 pmid: 28005860
92 P Panagiotopoulos, D G Papazoglou, A Couairon, S Tzortzakis. Sharply autofocused ring-Airy beams transforming into non-linear intense light bullets. Nature Communications, 2013, 4(1): 2622 pmid: 24131993
93 P Polynkin, M Kolesik, A Roberts, D Faccio, P Di Trapani, J Moloney. Generation of extended plasma channels in air using femtosecond Bessel beams. Optics Express, 2008, 16(20): 15733–15740 pmid: 18825212
94 P Polynkin, M Kolesik, J V Moloney, G A Siviloglou, D N Christodoulides. Curved plasma channel generation using ultraintense Airy beams. Science, 2009, 324(5924): 229–232 pmid: 19359582
95 M, Mills M S, Miri M A, Cheng W, Moloney J V, Kolesik M, Polynkin P, Christodoulides D N Scheller. Externally refuelled optical filaments. Nature Photonics, 2014, 8(4): 297–301
96 E Matsubara, M Nagai, M Ashida. Ultrabroadband coherent electric field from far infrared to 200 THz using air plasma induced by 10 fs pulses. Applied Physics Letters, 2012, 101(1): 011105
97 J M Manceau, A Averchi, F Bonaretti, D Faccio, P Di Trapani, A Couairon, S Tzortzakis. Terahertz pulse emission optimization from tailored femtosecond laser pulse filamentation in air. Optics Letters, 2009, 34(14): 2165–2167 pmid: 19823536
98 J Zhao, L Guo, W Chu, B Zeng, H Gao, Y Cheng, W Liu. Simple method to enhance terahertz radiation from femtosecond laser filament array with a step phase plate. Optics Letters, 2015, 40(16): 3838–3841 pmid: 26274673
99 X Chu. Evolution of an Airy beam in turbulence. Optics Letters, 2011, 36(14): 2701–2703 pmid: 21765514
100 I Dolev, I Kaminer, A Shapira, M Segev, A Arie. Experimental observation of self-accelerating beams in quadratic nonlinear media. Physical Review Letters, 2012, 108(11): 113903
101 J Dai, X C Zhang. Terahertz wave generation from thin metal films excited by asymmetrical optical fields. Optics Letters, 2014, 39(4): 777–780 pmid: 24562204
102 H G Roskos, M D Thomson, M Kreß, T Löffler. Broadband THz emission from gas plasmas induced by femtosecond optical pulses: From fundamentals to applications. Laser & Photonics Reviews, 2007, 1(4): 349–368
103 T I Oh, Y S You, N Jhajj, E W Rosenthal, H M Milchberg, K Y Kim. Scaling and saturation of high-power terahertz radiation generation in two-color laser filamentation. Applied Physics Letters, 2013, 102(20): 201113
104 A Gorodetsky, A D Koulouklidis, M Massaouti, S Tzortzakis. Physics of the conical broadband terahertz emission from two-color laser-induced plasma filaments. Physical Review A., 2014, 89(3): 033838
105 A Talebpour, S Petit, S L Chin. Re-focusing during the propagation of a focused femtosecond Ti:sapphire laser pulse in air. Optics Communications, 1999, 171(4–6): 285–290
106 B Clough, N Karpowicz, X C Zhang. Modulation of electron trajectories inside a filament for single-scan coherent terahertz wave detection. Applied Physics Letters, 2012, 100(12): 121105
107 F Buccheri, K Liu, X C Zhang. Terahertz radiation enhanced emission of fluorescence from elongated plasmas and microplasmas in the counter-propagating geometry. Applied Physics Letters, 2017, 111(9): 091103
108 F Martin, R Mawassi, F Vidal, I Gallimberti, D Comtois, H Pepin, J C Kieffer, H P Mercure. Spectroscopic study of ultrashort pulse laser breakdown plasmas in air. Applied Spectroscopy, 2002, 56(11): 1444–1452
109 J Liu, X C Zhang. Enhancement of laser-induced fluorescence by intense terahertz pulses in gases. IEEE Journal of Selected Topics in Quantum Electronics, 2011, 17(1): 229–236
110 J Liu, J Dai, X C Zhang. Ultrafast broadband terahertz waveform measurement utilizing ultraviolet plasma photoemission. Journal of the Optical Society of America B, Optical Physics, 2011, 28(4): 796–804
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