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Frontiers of Optoelectronics

Front. Optoelectron.    2014, Vol. 7 Issue (2) : 199-219     DOI: 10.1007/s12200-014-0397-3
Toward remote sensing with broadband terahertz waves
Benjamin CLOUGH1,Xi-Cheng ZHANG2,3,*()
1. Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA
2. The Institute of Optics, University of Rochester, Rochester, NY 14627-0186, USA
3. Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
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This paper studies laser air-photonics used for remote sensing of short pulses of electromagnetic radiation at terahertz frequency. Through the laser ionization process, the air is capable of generating terahertz field strengths greater than 1 MV/cm, useful bandwidths over 100 terahertz, and highly directional emission patterns. Following ionization and plasma formation, the emitted plasma acoustic or fluorescence can be modulated by an external terahertz field to serve as omnidirectional, broadband, electromagnetic sensor. These results help to close the “terahertz gap” once existing between electronic and optical frequencies, and the acoustic and fluorescence detection methodologies developed provide promising new avenues for extending the useful range of terahertz wave technology. Our experimental results indicate that by hearing the sound or seeing the fluorescence, coherent detection of broadband terahertz wave at remote distance is feasible.

Keywords terahertz      air      plasma      fluorescence      acoustic     
Corresponding Authors: Xi-Cheng ZHANG   
Issue Date: 25 June 2014
 Cite this article:   
Benjamin CLOUGH,Xi-Cheng ZHANG. Toward remote sensing with broadband terahertz waves[J]. Front. Optoelectron., 2014, 7(2): 199-219.
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Xi-Cheng ZHANG
Fig.1  (a) Schematic diagram of a THz-ABCD spectroscopic system in both transmission and reflection mode. The system can be converted from transmission to reflection mode by taking out the mirrors indicated with an enclosing dashed box. PMT: photomultiplier tube; BS: beamsplitter; β-BBO: beta-barium borate; (b) photograph of laser-induced air-plasma created after focusing the optical beam from left to right through a lens (left) and mounted nonlinear crystal (center) used for second harmonic generation. The bright horizontal line emits an intense, highly directional terahertz field to the right
Fig.2  (a) Dependence of terahertz field on fundamental (ω) pulse energy, with fixed second-harmonic (2ω) pulse energy; (b) dependence of terahertz field on second-harmonic pulse energy, with fixed fundamental pulse energy. The solid line and curve are the linear and square-root fits, respectively. Reprinted figure with permission from Ref. [4]
Fig.3  (a) Time-resolved terahertz signals generated and detected using dry nitrogen gas as compared to conventional electro-optic (EO) crystal detection in ZnTe. The probe beam for air detection has energy of 85 μJ and pulse duration of 32 fs; (b) corresponding spectra after Fourier transformation
Fig.4  (a) Basic concept of THz-ABCD: electrodes are placed at the geometric focus of collinearly focused terahertz and optical probe beams with a variable time delay. Second harmonic light is induced from the terahertz 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. Data in (b) courtesy of Dr. Xiaofei Lu
Fig.5  3D-rendered Solidworks model of the high voltage square wave modulator
Fig.6  N-channel MOSFET full bridge topology used for switching voltages with drive signals A and B
Fig.7  Alternating voltage bias using an N-channel MOSFET bridge
Fig.8  Square wave high voltage modulator operating at maximum output voltage as determined by the DC-DC converter. The laser TTL output is sent to the modulator and a voltage divider is used to monitor the CH1 output. When operating with electrodes, the total output potential is CH1-CH2, twice that shown
Fig.9  Commercialized high voltage square wave modulator sold through Zomega Terahertz Corporation
Fig.10  3D rendered Solidworks model of the pulsed high voltage modulator prototype
Fig.11  Digital implementation of phase locked loop in a Xilinx CPLD to synchronize the digital circuitry timing to the laser trigger signal
Fig.12  Electronic pulse phase control circuitry implemented in the Xilinx CPLD. CB16X1: 16-bit loadable cascadable bidirectional binary counter; CB16CE: 16-bit cascadable binary counter; ADSU16: 16-bit cascadable adder/subtracter; COMP16: 16-bit Identity Comparator
Fig.13  Analog circuitry interfaced to Xilinx CPLD for the phase locked loop
Fig.14  A compact, high Q-factor, high turns-ratio transformer is pulsed using the output from the MOSFET bridge. The polarity of the high voltage output pulse is determined by the input pulse timing
Fig.15  Phase-locked output of the pulsed high voltage modulator showing filed polarity altering between each trigger from the reference
Fig.16  (a) Experimental geometry for THz-REEF from air-plasma using a single-color laser pulse excitation; (b) electron acceleration in the terahertz field and collision with neighboring molecules; (c) THz-enhanced fluorescence spectra of nitrogen gas-plasma under influence of 100 kV/cm peak field. ? IEEE, reprinted, with permission, from Ref. [24]
Fig.17  (a) Time-resolved air-plasma fluorescence enhancement from terahertz wave interaction with antiparallel, symmetric, and parallel electron drift velocities with respect to the laser field, controlled by changing the relative phase between the ω and 2ω optical pulses; (b) subtracting the parallel curve from the antiparallel curve removes the incoherent energy transfer by electrons after inelastic collisions and scattering in random directions. This reveals the terahertz waveform in the form of fluorescence modulation. The optical pulse leads the terahertz pulse in time for delay td<0
Fig.18  “All air-plasma” terahertz spectroscopy system. Air-plasma filaments are used for both generation and detection of the terahertz electromagnetic radiation. (Light blue: terahertz), (Red: 800 nm pulse), (Blue: 400 nm pulse), (Purple: nitrogen fluorescence). Nitrogen fluorescence emitted from the probe plasma carries the encoded terahertz pulse information
Fig.19  (a) Terahertz pulses recovered from the radiation-enhanced-emission of fluorescence (REEF) and electro-optic sampling method using a 100 μm thick<110>GaP crystal; (b) corresponding spectrum after Fourier transformation
Fig.20  (a) Terahertz waveforms for pellet samples NG, 2,4-DNT, and HMX containing 20% chemical mixed with polyethylene obtained using electro-optic sampling; (b) absorbance signatures corresponding to samples in (a); (c) identical samples and corresponding waveforms obtained using radiation enhanced emission of fluorescence (REEF) encoding; (d) absorbance signatures corresponding to samples in (c). All curves are offset for clarity
Fig.21  (a) Experimental setup for performing terahertz enhanced acoustics using single-color femtosecond laser excitation; (b) single photoacoustic waveforms measured at 5 mm distance with (red-dashed) and without (black-solid) a 100 kV/cm terahertz field. The insert shows the acoustic spectra in linear scale. Amp.: amplitude; Acous. Freq.: acoustic frequency
Fig.22  Measured terahertz field dependence of acoustic pressure (red dots) at 100 kHz and quadratic fit (blue dashed line)
Fig.23  Normalized pressure enhancement signal at 100 kHz as a function of time delay td. Region I: terahertz pulse leads the optical pulse in time; region II: terahertz pulse trails the optical pulse in time. The dashed line is the calculated signal. Inset shows the acoustic signal at 100 kHz for different terahertz intensities incident on single-color laser-induced plasma and a linear fit
Fig.24  Experimental schematic for the THz-enhanced acoustics using two-color femtosecond laser excitation
Fig.25  Dependence of terahertz wave generation from plasma on the relative phase delay between 800 nm pulse and 400 nm pulse. The arrow refers to the electron drift direction. At the maxima of the terahertz emission, the electron drift velocity is highly asymmetric, while at the minima of the terahertz emission, the electron drift velocity is nearly symmetric
Fig.26  (a) Acoustic pressure enhancement as a function of time delay td at relative phase delay of π/2 (solid line) and –π/2 (dashed line). Inset, the experimental schematic of interaction of the terahertz pulse and two-color laser plasma; (b) comparison between the terahertz time-domain waveforms measured by terahertz-wave-enhanced acoustic emission and electro-optic sampling respectively in ambient air; (c) corresponding spectral comparison of the waveforms in (b). TEA; terahertz enhanced acoustics; EO: electro-optic
Fig.27  Temporal and spectral characteristics of acoustic pulses collected using a broadband microphone mounted at the 3 inch focus of a 12 inch diameter parabolic reflector. (a) Normalized temporal pressure transients at 0.5 and 11 meters from the plasma source; (b) normalized spectral comparison of 0.5 and 11 meter acoustic pulse propagation
Fig.28  (a) Acoustic pulses collected with and without direct line of sight to the plasma acoustic source from several meters; (b) terahertz enhanced acoustic signal collected at standoff distance of 1 and 3 meters from the plasma source using a 12" diameter parabolic reflector with the microphone positioned at the 3" focus
1 Hamster H, Sullivan A, Gordon S, White W, Falcone R W. Subpicosecond, electromagnetic pulses from intense laser-plasma interaction. Physical Review Letters, 1993, 71(17): 2725–2728
doi: 10.1103/PhysRevLett.71.2725 pmid: 10054760
2 Cook D J, Hochstrasser R M. Intense terahertz pulses by four-wave rectification in air. Optics Letters, 2000, 25(16): 1210–1212
doi: 10.1364/OL.25.001210 pmid: 18066171
3 Bartel T, Gaal P, Reimann K, Woerner M, Elsaesser T. Generation of single-cycle THz transients with high electric-field amplitudes. Optics Letters, 2005, 30(20): 2805–2807
doi: 10.1364/OL.30.002805 pmid: 16252781
4 Xie X, Dai J M, Zhang X C. Coherent control of THz wave generation in ambient air. Physical Review Letters, 2006, 96(7): 075005-1–075005-4
doi: 10.1103/PhysRevLett.96.075005 pmid: 16606102
5 Dai J M, Xie X, Zhang X C. Detection of broadband terahertz waves with a laser-induced plasma in gases. Physical Review Letters, 2006, 97(10): 103903-1–103903-4
doi: 10.1103/PhysRevLett.97.103903 pmid: 17025819
6 Lu X F, Karpowicz N, Chen Y Q, Zhang X C. Systematic study of broadband terahertz gas sensor. Applied Physics Letters, 2008, 93(26): 261106-1–261106-3
doi: 10.1063/1.3056119
7 Ho I C, Guo X Y, Zhang X C. Design and performance of reflective terahertz air-biased-coherent-detection for time-domain spectroscopy. Optics Express, 2010, 18(3): 2872–2883
doi: 10.1364/OE.18.002872 pmid: 20174116
8 Kim K Y, Glownia J H, Taylor A J, Rodriguez G. Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields. Optics Express, 2007, 15(8): 4577–4584
doi: 10.1364/OE.15.004577 pmid: 19532704
9 Karpowicz N, Zhang X C. Coherent terahertz echo of tunnel ionization in gases. Physical Review Letters, 2009, 102(9): 093001-1–093001-4
doi: 10.1103/PhysRevLett.102.093001 pmid: 19392516
10 Wu H C, Meyer-ter-Vehn J, Sheng Z M. Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses. New Journal of Physics, 2008, 10(4): 043001-1–043001-10
doi: 10.1088/1367-2630/10/4/043001
11 Silaev A A, Vvedenskii N V. Quantum-mechanical approach for calculating the residual quasi-dc current in a plasma produced by a few-cycle laser pulse. Physica Scripta, 2009, T135: 014024-1–014024-5
doi: 10.1088/0031-8949/2009/T135/014024
12 Karpowicz N, Dai J, Lu X, Chen Y, Yamaguchi M, Zhao H, Zhang X C, Zhang L, Zhang C, Price-Gallagher M, Fletcher C, Mamer O, Lesimple A, Johnson K. Coherent heterodyne time-domain spectrometry covering the entire “terahertz gap”. Applied Physics Letters, 2008, 92(1): 011131-1–011131-3
doi: 10.1063/1.2828709
13 Xu J, Zhang X C. Introduction to THz Wave Photonics, New York: Springer, 2010
14 Wu Q, Zhang X C. Free space electro optic sampling of terahertz beams. Applied Physics Letters, 1995, 67(24): 3523–3525
doi: 10.1063/1.114909
15 Jepsen P U, Winnewisser C, Schall M, Schyja V, Keiding S R, Helm H. Detection of THz pulses by phase retardation in lithium tantalite. Physical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 1996, 53(4): R3052–R3054
doi: 10.1103/PhysRevE.53.R3052
16 Nahata A, Auston D, Heinz T, Wu C. Coherent detection of freely propagating terahertz radiation by electro optic sampling. Applied Physics Letters, 1996, 68(2): 150–152
doi: 10.1063/1.116130
17 Thomson M D, Blank V, Roskos H G. Terahertz white-light pulses from an air plasma photo-induced by incommensurate two-color optical fields. Optics Express, 2010, 18(22): 23173–23182
doi: 10.1364/OE.18.023173 pmid: 21164658
18 Nahata A, Heinz T F. Detection of freely propagating terahertz radiation by use of optical second-harmonic generation. Optics Letters, 1998, 23(1): 67–69
doi: 10.1364/OL.23.000067 pmid: 18084414
19 Cook D, Chen J, Morlino E, Hochstrasser R. Terahertz-field-induced second-harmonic generation measurements of liquid dynamics. Chemical Physics Letters, 1999, 309(3–4): 221–228
doi: 10.1016/S0009-2614(99)00668-5
20 Shelton D P. Nonlinear-optical susceptibilities of gases measured at 1064 and 1319 nm. Physical Review A, 1990, 42(5): 2578–2592
doi: 10.1103/PhysRevA.42.2578 pmid: 9904326
21 Newport Corporation. Newport Announces Terahertz Pulse Generation Kit. 2012,
22 Zomega Terahertz Corporation. 2012,
23 Liu J L, Zhang X C. Terahertz-radiation-enhanced emission of fluorescence from gas plasma. Physical Review Letters, 2009, 103(23): 235002-1–235002-4
doi: 10.1103/PhysRevLett.103.235002 pmid: 20366153
24 Liu J L, Zhang X C. Enhancement of laser-induced fluorescence by intense terahertz pulses in gases. IEEE Journal on Selected Topics in Quantum Electronics, 2011, 17(1): 229–236
doi: 10.1109/JSTQE.2010.2046142
25 Liu J L, Dai J M, Chin S L, Zhang X C. Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases. Nature Photonics, 2010, 4(9): 627–631
doi: 10.1038/nphoton.2010.165
26 Davies A G, Burnett A D, Fan W, Linfield E H, Cunningham J E. Terahertz spectroscopy of explosives and drugs. Materials Today, 2008, 11(3): 18–26
doi: 10.1016/S1369-7021(08)70016-6
27 Ferguson B, Zhang X C. Materials for terahertz science and technology. Nature Materials, 2002, 1(1): 26–33
doi: 10.1038/nmat708 pmid: 12618844
28 Ho L, Pepper M, Taday P. Terahertz spectroscopy: signatures and fingerprints. Nature Photonics, 2008, 2(9): 541–543
doi: 10.1038/nphoton.2008.174
29 Hebling J, Yeh K L, Hoffmann M C, Bartal B, Nelson K A. 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
doi: 10.1364/JOSAB.25.0000B6
30 Wanke M C, Mangan M A, Foltynowicz R J. Atmospheric Propagation of THz Radiation. Technical Report SAND2005-6389. Albuquerque: Sandia National Laboratories, 2005
31 Dai J M, Zhang X C. Demonstration of 17 meter standoff THz wave generation. In: Proceedings of Nonlinear Optics: Materials, Fundamentals and Applications. Optical Society of America, 2009, NWA1
32 Dai J M, Zhang X C. Terahertz wave generation from gas plasma using a phase compensator with attosecond phase-control accuracy. Applied Physics Letters, 2009, 94(2): 021117-1–021117-3
doi: 10.1063/1.3068501
33 Wang T J, Yuan S, Chen Y P, Daigle J F, Marceau C, Théberge F, Chateauneuf M, Dubois J, Chin S L. Toward remote high energy terahertz generation. Applied Physics Letters, 2010, 97(11): 111108-1–111108-3
doi: 10.1063/1.3490702
34 Clough B, Liu J L, Zhang X C. Laser-induced photoacoustics influenced by single-cycle terahertz radiation. Optics Letters, 2010, 35(21): 3544–3546
doi: 10.1364/OL.35.003544 pmid: 21042344
35 Liu J L, Clough B, Zhang X C. Enhancement of photoacoustic emission through terahertz-field-driven electron motions. Physical Review E: Statistical, Nonlinear, and Soft Matter Physics, 2010, 82(6): 066602-1–066602-6
doi: 10.1103/PhysRevE.82.066602 pmid: 21230746
36 Roskos H G, Thomson M D, Kre? M, L?ffler T. Broadband THz emission from gas plasmas induced by femtosecond optical pulses: From fundamentals to applications. Laser & Photonics Reviews, 2007, 1(4): 349–368
doi: 10.1002/lpor.200710025
37 Chen J, Chen Y Q, Zhao H W, Bastiaans G J, Zhang X C. Absorption coefficients of selected explosives and related compounds in the range of 0.1-2.8 THz. Optics Express, 2007, 15(19): 12060–12067
doi: 10.1364/OE.15.012060 pmid: 19547570
38 Liu H B, Zhong H, Karpowicz N, Chen Y Q, Zhang X C. Terahertz spectroscopy and imaging for defense and security applications. Proceedings of the IEEE, 2007, 95(8): 1514–1527
doi: 10.1109/JPROC.2007.898903
39 Filin A, Compton R, Romanov D A, Levis R J. Impact-ionization cooling in laser-induced plasma filaments. Physical Review Letters, 2009, 102(15): 155004-1–155004-4
doi: 10.1103/PhysRevLett.102.155004 pmid: 19518642
40 Radziemski L J, Loree T R, Cremers D A, Hoffman N M. Time-resolved laser-induced breakdown spectrometry of aerosols. Analytical Chemistry, 1983, 55(8): 1246–1252
doi: 10.1021/ac00259a016
41 Sobral H, Villagran-Muniz M, Navarro-Gonzalez R, Raga A C. Temporal evolution of the shock wave and hot core air in laser induced plasma. Applied Physics Letters, 2000, 77(20): 3158–3160
doi: 10.1063/1.1324986
42 Raizer Y P. Laser-Induced Discharge Phenomena. New York: Consultants Bureau, 1977
43 Diebold G J. Topics in Current Physics. Heidelberg: Springer-Verlag, 1989
44 Fay R D. Plane sound waves of finite amplitude. Journal of the Acoustical Society of America, 1931, 3(2A): 222–241
doi: 10.1121/1.1915557
45 Hamilton M, Blackstock D. Nonlinear Acoustics. San Diego: Academic Press, 1997
46 Mlejnek M, Wright E M, Moloney J V. Femtosecond pulse propagation in argon: A pressure dependence study. Physical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 1998, 58(4): 4903–4910
doi: 10.1103/PhysRevE.58.4903
47 Tzortzakis S, Prade B, Franco M, Mysyrowicz A. Time-evolution of the plasma channel at the trail of a self-guided IR femtosecond laser pulse in air. Optics Communications, 2000, 181(1–3): 123–127
doi: 10.1016/S0030-4018(00)00734-3
48 Gibson G N, Freeman R R, McIlrath T J. Dynamics of the high-intensity multiphoton ionization of N2. Physical Review Letters, 1991, 67(10): 1230–1233
doi: 10.1103/PhysRevLett.67.1230 pmid: 10044093
49 Yu J, Mondelain D, Kasparian J, Salmon E, Geffroy S, Favre C, Boutou V, Wolf J P. Sonographic probing of laser filaments in air. Applied Optics, 2003, 42(36): 7117–7120
doi: 10.1364/AO.42.007117 pmid: 14717285
50 Ni X W, Zou B, Chen J P, Biao B M, Shen Z H, Lu J, Cui Y P. On the generation of laser-induced plasma acoustic waves. Acta Physica Sinica, 1998, 7(2): 143–147
51 Kim K Y, Glownia J H, Taylor A J, Rodriguez G. Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields. Optics Express, 2007, 15(8): 4577–4584
doi: 10.1364/OE.15.004577 pmid: 19532704
52 Dai J, Karpowicz N, Zhang X C. Coherent polarization control of terahertz waves generated from two-color laser-induced gas plasma. Physical Review Letters, 2009, 103(2): 023001-1–023001-4
doi: 10.1103/PhysRevLett.103.023001 pmid: 19659200
53 Kim K Y, Taylor A J, Glownia J H, Rodriguez G. Coherent control of terahertz supercontinuum generation in ultrafast laser-gas interactions. Nature Photonics, 2008, 2(10): 605–609
doi: 10.1038/nphoton.2008.153
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