Abstract

The physical mechanism for sensing broadband terahertz (THz) wave via using femtosecond (fs) laser induced gas plasma without any local accessory near the plasma, i.e. THz air breakdown coherent detection, is systemically investigated by utilizing the transient photocurrent model. Previous observed results, such as conversion from incoherent to coherent detection, can be numerically obtained. Further calculations and analysis show that it is through modification of the gas ionization process, and not acceleration of freed electrons or through a four-wave-mixing (FWM) process, that the THz waveforms can be encoded into the detected second harmonic (SH) signals.

© 2012 OSA

1. Introduction

Laser-induced gas plasma can be used to generate strong (E-field~MV/cm), broadband (0.1-40THz), and coherent THz waves through a complex nonlinear physical process [13]. On the other hand, plasma in ambient air or selected gases can also be used as THz wave sensors [36]. Unlike solid state materials commonly used in THz time domain spectroscopy (THz-TDS) system, such as electro-optical crystals and photon-conductive antennas [7], gas medium have no phonon resonance or echoes due to THz waves or optical reflection. Moreover, some gaseous medium, from the point of use-cost, is a better choice than the solid state materials mentioned above since there is no concern about their damage.

For the generation of broadband and strong THz pulses from two-color (ω0-2ω0) laser induced gas plasma, its physical mechanism was initially treated as a FWM process, which, however, failed to explain some subsequent measured results, e.g. saturation of THz output [2]. To solve these problems, Kim et al developed a so-called transient photocurrent (PC) model, the results of which showed that coherent THz waves had originated from a net electron current surge generated by an asymmetric two-color laser field, indicating that plasma plays a key role for generation [8, 9]. Note that many other models have been also built to explain this complex process [1012].

Broadband THz detection via using fs-laser induced gas plasma, i.e. THz Air Breakdown Coherent Detection (THz-ABCD), was firstly reported in 2006 [4], the authors of which used a phenomenological FWM model to explain their measured results by introducing the SH component of white light from the plasma as a local oscillator that is depending on probe laser intensity (Note that THz-field induced SH generation effects in liquid medium has been reported in 1999 [13]). However, a detailed microscopic physical picture of their observed phenomena, especially how the THz information is encoded into measured SH emission, was missing up to now since the THz detection with gas plasma, at first glance, was generally treated as an inverse process of THz generation according to the FWM model [4]. Moreover, a subsequent altered sensing method, by adding an AC bias voltage at the location of plasma, namely THz Air Biased Coherent Detection (also abbreviated as THz-ABCD) [5], attracted more attention and was widely used in labs due to its lower laser intensity. Nevertheless for application outside the labs, especially urgent need of remote THz sensing in ambient atmosphere [1], the former THz-ABCD could have more advantages since it doesn’t need any local accessory at the location of plasma, i.e. AC bias. Thus it is very necessary to elucidate the microscopic process of the former THz-ABCD.

In this paper, we theoretically investigate the missed microscopic process of the THz Air Breakdown Coherent Detection by using the well-developed PC model [8, 9]. The observed results in experiments, such as transition of detection mode and SH intensity clamping [4], can be numerically reproduced. Further analysis shows that it is mainly through modification of the gas ionization process that THz waveforms’ information can be encoded into the measured SH signals. Moreover, our results demonstrate that FWM model used in Ref. 4 does not appear to account for the THz Air Breakdown Coherent Detection.

It should be noticed that the followed “THz-ABCD” in this paper means the former one mentioned above.

2. THz-ABCD and PC model

Firstly, we briefly describe THz-ABCD process and transient PC model. A probe fs-laser beam (ω0), as schematically illustrated in Fig. 1 , is focused into gas to ignite gas plasma, then in which the freed electrons will be accelerated by this incident field and thereby form an oscillating currentJ. Thus electromagnetic (EM) waves with all frequencies will radiate from such plasma. When THz signal with a delay time Δt is also focused on the plasma, some fluorescence components in the total emission Eout(t) [14, 15], such as SH emission (2ω0), will be significantly influenced by this incident detected waves through a complex interaction that will be investigated in this paper. So by observing such modulated 2ω0components, one can indirectly get the information of THz waves. Note that the attachment and recombination of such electrons can be ignored since the time of these processes is much longer than that of radiation [11]. The plasma, in addition, can be approximately treated as a uniform spheroid with radius w0 since its size, compared with the THz wavelength, is sufficiently small [8, 9].

 

Fig. 1 Schematic diagram of THz ABCD: a probe laser pulse with center frequency ω0 and THz pulse with delayΔtare focused into gas medium. The SH emission with THz information from plasma can be collected by lens and a 2ω0narrow band filter, and then detected by a photomultiplier tube (PMT).

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Using PC model, one can write the radiation field from plasma center as [8, 9, 12]:

Eout(t)dJ(t)dt=4e2w033mEin(t)Ne(t),
where, mandeare the mass and charge of the electron, respectively. The plasma densityNe(t), determined by total incident optical fieldEin(t), species and density of gas medium, can be calculated via Ammosov-Delone-Krainov (ADK) tunneling [16], static tunneling [17] or other ionization models [18]. Note that we use the static tunneling model in our simulation of ionization process, and the gas medium, corresponding to the original experiments [4], is the nitrogen.

Actually, Eq. (1) represents a net radiated field with all frequencies from the plasma. In order to obtain the SH signalE2ω0(t)from Eq. (1), one can use the Fourier transformation, i.e.E2ω0(t)++Eout(t)eiωtdtf2ω0(ω)eiωtdω, in whichf2ω0(ω)is a narrow band pass filter function with center frequency at2ω0. Then the SH intensity can be calculated according to the expressionI2ω0τ/2+τ/2[E2ω0(t)]2dtin the duration timeτof a probe laser pulse. By neglecting the absorption, total incident field can be written asEin(t)=Eω0(t)+ETHz(t+Δt). Thus treating the delay timeΔt as independent variable, one can calculateI2ω0containing the information of detected THz waveform with different probe laser energies, as shown in Fig. 2 .

 

Fig. 2 (a) The real incident THz waveform and spectrum (inset), (b) calculated SH signal waveforms at different probe energies.

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3. Simulation and discussion

In our simulation, the density of gas molecules and radius are assumed to be 5×1019cm3 and10μm, respectively. The probe laser pulse has a Gaussian formation with center wavelength λ=800nmand full width at half maximum (FWHM)TFWHM=30fs. Note that the THz field is an invariant with a 100kV/cmpeak field when laser pulse energy Wis changed, whereWw02TFWHMI0 andI0 is the peak intensity of probe laser.

The calculated SH intensity signals containing THz information, as shown in Fig. 2(b), have a unipolar feature whenWis30μJ, corresponding to the incoherent detection obtained in experiments. The calculated waveforms, with the increasing of probe laser energy, begin to show some bipolar characteristics, and a complete bipolar waveforms appears nearly whenW=150μJ. When probe pulse energy is200μJ, one can obtain a waveform nearly identical to that of the real incident THz field (shown in Fig. 2(a)), referred to as coherent detection of the THz waves. Such results, i.e. transition of detection mode, have good agreements with that of experiments reported in Refs. 3 and 4.

Another observed result, i.e. the dependence of peak SH signalI2ω0on probe laser energiesW, based on which detection mode can be categorized as incoherent, hybrid and coherent detection, is reproduced as red line in Fig. 3 . The measuredI2ω0, in original report [4], could be phenomenally fitted as a quadratic function at lower probe energy according to FWM model, which, however, failed to explain the situation at high-power probe laser, namely the intensity clamping [46]. Our further calculation shows that the blue line shown in Fig. 3, i.e. plasma densityNeinduced by probe lasers versusW, has a similar evolution characteristic with that ofI2ω0. Particularly, when the complete coherent detection, corresponding to such intensity clamping, emerges atW=200μJ,Nebegins to be saturated, indicating that plasma density could play a key role in whole detection process. It is worth noted that there exist other additional saturation mechanisms, e.g. plasma defocusing effects. Although such mechanism could change some numerical results, e.g. the lowest probe laser intensity for coherent detection, the main result, i.e. conversion from incoherent to coherent detection as shown in Fig. 3, will not be significantly affected.

 

Fig. 3 The plasma density (blue line) at the focus point and the peak SH signal (red line) versus probe pulse energyW.

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To manifest the physical nature of such experimental and our numerical results obtained above, a detailed analysis is performed as followed. Since plasma densityNeis determined by total incident fieldEin(t), Eq. (1) can be rewritten asEoutω0+T,ω0+T(t)Ein(t)Ne(|Ein(t)|), from which it is clear that the contribution of THz fieldETHz to plasma emission can be divided into two parts: one is participating the acceleration of freed electrons in plasma, the other is that to plasma densityNe. To answer the question that through which process the THz waves can be encoded into the observed SH signals in the whole detection process, we firstly investigate the effect of such waves on plasma emissionEoutω0+T,ω0(t)Ein(t)Neω0(|Eω0(t)|)only by means of accelerating freed electrons, i.e. meanwhile neglecting their contribution to the plasma density. Calculated spectrum of Eoutω0+T,ω0(t)is plotted with blue lines in Fig. 4 , from which it is clear that SH signals, with both low and high probe laser intensities, do not show any visible fluctuation at2ω0. However, the emissionEoutω0,ω0+T(t)Eω0(t)Neω0+T(|Ein(t)|), i.e. only considering THz waves contribute to plasma density, has significant changes at 2ω0 (red dot lines in Fig. 4), indicating that it is by involving gas ionization process that information of THz waves is encoded into the detected SH signals (2ω0). Moreover the coincidence between red and green dot lines (the spectrum of real emission Eoutω0+T,ω0+T(t)from gas plasma in THz-ABCD), especially near2ω0, also supports such conclusion.

 

Fig. 4 Radiation spectrum of plasma emission at different probe energies: (a) W=30μJ and (b)W=200μJ.

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Next we will show how the THz waves affect the ionization process. Since pulse width of a THz wave (~ps) is much longer than that of a probe laser (~fs), such detected wave can be approximately treated as a constant field in the duration time of laser pulse, leading to a small displacement on the previous symmetric laser waveform (Fig. 5(a) schematically shows such relation between monochromatic lightω0and THz E-field). Note that this asymmetry is directional due to positive and negative THz E-filed relative to probe laser field. As shown in experiments and our simulation, the bipolar characteristics of a THz waves, i.e. positive and negative fields of THz wave, can be resolved in coherent detection, while not in incoherent detection. Moreover it is by involving gas ionization process, as analyzed above, that information of THz waves is encoded into the detected SH signals. Thus to seek how the THz fields with different polarities affect to ionization process, we calculate the time derivative of plasma density (TDPD) with single probe laser pulseEω0,Eω0+ETHz andEω0ETHz, denoted asdNeω0/dt, dNeω0+T/dtanddNeω0T/dtrespectively, as shown in Fig. 5. From the insets of Fig. 5(b)-5(d), the TDPD distribution with both Eω0+ETHz (red line) and Eω0ETHz(green line), compared with that induced only byEω0 (blue line), has a small increment, indicating that THz field can affect the ionization process. When laser pulse is not strong (W=30μJ), as illustrated in Fig. 5(b), the TDPD distribution has a similar symmetric profile with probe pulse (cyan line), showing that gas ionization process occurs at both leading and trailing edge of a laser pulse. Note that the inset of Fig. 5(b) shows that although red line is different with green line at the probe pulse leading edge or trailing edge, further calculation shows that the area below these two lines is almost equivalent, while larger than that below blue line, indicating that both of these two hybrid incident fields, i.e. Eω0+ETHz andEω0ETHz, will produce more electrons than that generated by the single probe laserEω0. Thus for low probe intensity, THz fields with different polarities has nearly same influence to the generation of gas plasma, indicating that both of positive and negative field in a real THz pulse cannot be resolved, namely detecting a unipolar THz waveform.

 

Fig. 5 (a): Schematic diagrams of the relation between monochromatic laser (ω0) and THz filed; different TDPD induced by single probe laser pulse and that with THz and reversed THz at different probe pulse energiesW, (b)30μJ, (b) 100μJand (c) 200μJ.

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With the increasing of probe laser intensity, the TDPD distribution, as show in Fig. 5(c), begins to move to the leading edge of laser pulse and the previous symmetric profile is broken since more plasma is induced at the leading edge, in other words gas depletion appears at the trailing edge of laser pulse, which means that the intensity of SH emissions from gas plasma induced by Eω0+ETHz andEω0ETHz will be different, leading that some bipolar characteristics of THz waveform can be resolved. Furthermore, Fig. 5(d) illustrates that when W=200μJthe TDPD distribution has nonzero values only at the leading edge of laser pulse, in other words generation of plasma mainly occurs at leading edge, corresponding to the ionization saturation obtained above. Thus from the inset of Fig. 5(d), the TDPD caused by three incident fieldsEω0,Eω0+ETHz andEω0ETHz, respectively, has different profile in details, indicating different generation process of plasma, from which the E-field of THz pulse with different polarities can be resolved .

4. Conclusion

In conclusion, by using PC model, we systematically investigate the physical mechanism of THz-ABCD, which was previously understood as a reverse process of THz generation based on FWM model. The measured results, such as the transition of detection mode and SH intensity clamping, can be reproduced in our numerical calculation. Further analysis show that the information of THz waves can be encoded into the SH signals through modification of the gas ionization process, but not acceleration of freed electrons or through a FWM process.

Acknowledgments

The authors gratefully acknowledge support from the National Natural Science Foundation of China under Grant No.10974063, 60907045 and 61177095, Hubei Natural Science Foundation under grant No. 2010CDA001, Ph.D. Programs Foundation of Ministry of Education of China under grant No. 20100142110042, and the Fundamental Research Funds for the Central Universities, HUST: 2011TS001, 2012QN094 and 2012QN097.

References and links

1. B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012). [CrossRef]  

2. M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007). [CrossRef]  

3. J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011). [CrossRef]  

4. J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006). [CrossRef]   [PubMed]  

5. 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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008). [CrossRef]  

6. X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008). [CrossRef]  

7. X.-C. Zhang and J. Z. Xu, Introduction to THz Wave Photonics (Springer, 2009).

8. K. Y. Kim, J. H. Glownia, A. J. Taylor, and G. Rodriguez, “Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields,” Opt. Express 15(8), 4577–4584 (2007), http://www.opticsinfobase.org/oe/abstract.cfm?id=131706. [CrossRef]   [PubMed]  

9. K. Y. Kim, “Generation of coherent terahertz radiation in ultrafast laser-gas interactions,” Phys. Plasmas 16(5), 056706 (2009). [CrossRef]  

10. N. Karpowicz and X.-C. Zhang, “Coherent terahertz echo of tunnel ionization in gases,” Phys. Rev. Lett. 102(9), 093001 (2009). [CrossRef]   [PubMed]  

11. M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008). [CrossRef]   [PubMed]  

12. I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010). [CrossRef]   [PubMed]  

13. D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999). [CrossRef]  

14. J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010). [CrossRef]  

15. J. L. Liu and X.-C. Zhang, “Terahertz-radiation-enhanced emission of fluorescence from gas plasma,” Phys. Rev. Lett. 103(23), 235002 (2009). [CrossRef]   [PubMed]  

16. P. B. Corkum, “Plasma perspective on strong field multiphoton ionization,” Phys. Rev. Lett. 71(13), 1994–1997 (1993). [CrossRef]   [PubMed]  

17. P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989). [CrossRef]   [PubMed]  

18. H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008). [CrossRef]  

References

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  1. B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012).
    [Crossref]
  2. M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
    [Crossref]
  3. J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011).
    [Crossref]
  4. J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006).
    [Crossref] [PubMed]
  5. 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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
    [Crossref]
  6. X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
    [Crossref]
  7. X.-C. Zhang and J. Z. Xu, Introduction to THz Wave Photonics (Springer, 2009).
  8. K. Y. Kim, J. H. Glownia, A. J. Taylor, and G. Rodriguez, “Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields,” Opt. Express 15(8), 4577–4584 (2007), http://www.opticsinfobase.org/oe/abstract.cfm?id=131706 .
    [Crossref] [PubMed]
  9. K. Y. Kim, “Generation of coherent terahertz radiation in ultrafast laser-gas interactions,” Phys. Plasmas 16(5), 056706 (2009).
    [Crossref]
  10. N. Karpowicz and X.-C. Zhang, “Coherent terahertz echo of tunnel ionization in gases,” Phys. Rev. Lett. 102(9), 093001 (2009).
    [Crossref] [PubMed]
  11. M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
    [Crossref] [PubMed]
  12. I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
    [Crossref] [PubMed]
  13. D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
    [Crossref]
  14. J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
    [Crossref]
  15. J. L. Liu and X.-C. Zhang, “Terahertz-radiation-enhanced emission of fluorescence from gas plasma,” Phys. Rev. Lett. 103(23), 235002 (2009).
    [Crossref] [PubMed]
  16. P. B. Corkum, “Plasma perspective on strong field multiphoton ionization,” Phys. Rev. Lett. 71(13), 1994–1997 (1993).
    [Crossref] [PubMed]
  17. P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989).
    [Crossref] [PubMed]
  18. H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008).
    [Crossref]

2012 (1)

B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012).
[Crossref]

2011 (1)

J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011).
[Crossref]

2010 (2)

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
[Crossref]

2009 (3)

J. L. Liu and X.-C. Zhang, “Terahertz-radiation-enhanced emission of fluorescence from gas plasma,” Phys. Rev. Lett. 103(23), 235002 (2009).
[Crossref] [PubMed]

K. Y. Kim, “Generation of coherent terahertz radiation in ultrafast laser-gas interactions,” Phys. Plasmas 16(5), 056706 (2009).
[Crossref]

N. Karpowicz and X.-C. Zhang, “Coherent terahertz echo of tunnel ionization in gases,” Phys. Rev. Lett. 102(9), 093001 (2009).
[Crossref] [PubMed]

2008 (4)

M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
[Crossref] [PubMed]

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
[Crossref]

H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008).
[Crossref]

2007 (2)

K. Y. Kim, J. H. Glownia, A. J. Taylor, and G. Rodriguez, “Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields,” Opt. Express 15(8), 4577–4584 (2007), http://www.opticsinfobase.org/oe/abstract.cfm?id=131706 .
[Crossref] [PubMed]

M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
[Crossref]

2006 (1)

J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006).
[Crossref] [PubMed]

1999 (1)

D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
[Crossref]

1993 (1)

P. B. Corkum, “Plasma perspective on strong field multiphoton ionization,” Phys. Rev. Lett. 71(13), 1994–1997 (1993).
[Crossref] [PubMed]

1989 (1)

P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989).
[Crossref] [PubMed]

Babushkin, I.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Bergé, L.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Brunel, F.

P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989).
[Crossref] [PubMed]

Burnett, N. H.

P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989).
[Crossref] [PubMed]

Chen, J. X.

D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
[Crossref]

Chen, M.

M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
[Crossref] [PubMed]

Chen, Y.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
[Crossref]

Chin, S. L.

J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
[Crossref]

Clough, B.

B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012).
[Crossref]

Cook, D. J.

D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
[Crossref]

Corkum, P. B.

P. B. Corkum, “Plasma perspective on strong field multiphoton ionization,” Phys. Rev. Lett. 71(13), 1994–1997 (1993).
[Crossref] [PubMed]

P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989).
[Crossref] [PubMed]

Dai, J.

B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012).
[Crossref]

J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011).
[Crossref]

J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
[Crossref]

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006).
[Crossref] [PubMed]

Elsaesser, T.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Fletcher, C.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Glownia, J. H.

Herrmann, J.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Hochstrasser, R. M.

D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
[Crossref]

Johnson, K.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Karpowicz, N.

N. Karpowicz and X.-C. Zhang, “Coherent terahertz echo of tunnel ionization in gases,” Phys. Rev. Lett. 102(9), 093001 (2009).
[Crossref] [PubMed]

X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
[Crossref]

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Kim, K. Y.

Köhler, C.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Kreß, M.

M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
[Crossref]

Kuehn, W.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Lesimple, A.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Liu, J.

J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011).
[Crossref]

J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
[Crossref]

Liu, J. L.

J. L. Liu and X.-C. Zhang, “Terahertz-radiation-enhanced emission of fluorescence from gas plasma,” Phys. Rev. Lett. 103(23), 235002 (2009).
[Crossref] [PubMed]

Löffler, T.

M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
[Crossref]

Lu, X.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
[Crossref]

Mamer, O.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Meyer-ter-Vehn, J.

H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008).
[Crossref]

Morlino, E. A.

D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
[Crossref]

Peng, X. Y.

M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
[Crossref] [PubMed]

Price-Gallagher, M.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Pukhov, A.

M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
[Crossref] [PubMed]

Reimann, K.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Rodriguez, G.

Roskos, H. G.

M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
[Crossref]

Sheng, Z.

H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008).
[Crossref]

Skupin, S.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Taylor, A. J.

Thomson, M. D.

M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
[Crossref]

Willi, O.

M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
[Crossref] [PubMed]

Woerner, M.

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

Wu, H.

H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008).
[Crossref]

Xie, X.

J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006).
[Crossref] [PubMed]

Yamaguchi, M.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Zhang, C.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Zhang, L.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Zhang, X.-C.

B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012).
[Crossref]

J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011).
[Crossref]

J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
[Crossref]

J. L. Liu and X.-C. Zhang, “Terahertz-radiation-enhanced emission of fluorescence from gas plasma,” Phys. Rev. Lett. 103(23), 235002 (2009).
[Crossref] [PubMed]

N. Karpowicz and X.-C. Zhang, “Coherent terahertz echo of tunnel ionization in gases,” Phys. Rev. Lett. 102(9), 093001 (2009).
[Crossref] [PubMed]

X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
[Crossref]

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006).
[Crossref] [PubMed]

Zhao, H.

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

Appl. Phys. Lett. (2)

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, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92(1), 011131 (2008).
[Crossref]

X. Lu, N. Karpowicz, Y. Chen, and X.-C. Zhang, “Systematic study of broadband terahertz gas sensor,” Appl. Phys. Lett. 93(26), 261106 (2008).
[Crossref]

Chem. Phys. Lett. (1)

D. J. Cook, J. X. Chen, E. A. Morlino, and R. M. Hochstrasser, “Terahertz-field-induced second-harmonic generation measurements of liquid dynamics,” Chem. Phys. Lett. 309(3-4), 221–228 (1999).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (1)

J. Dai, J. Liu, and X.-C. Zhang, “Terahertz wave air photonics: terahertz wave generation and detection with laser-induced gas plasma,” IEEE J. Sel. Top. Quantum Electron. 17(1), 183–190 (2011).
[Crossref]

Laser Photon. Rev. (1)

M. D. Thomson, M. Kreß, T. Löffler, and H. G. Roskos, “Broadband THz emission from gas plasmas induced by femtosecond optical pulses: from fundamentals to applications,” Laser Photon. Rev. 1(4), 349–368 (2007).
[Crossref]

Mater. Today (1)

B. Clough, J. Dai, and X.-C. Zhang, “Laser air photonics: beyond the terahertz gap,” Mater. Today 15(1-2), 50–58 (2012).
[Crossref]

Nat. Photonics (1)

J. Liu, J. Dai, S. L. Chin, and X.-C. Zhang, “Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases,” Nat. Photonics 4(9), 627–631 (2010).
[Crossref]

New J. Phys. (1)

H. Wu, J. Meyer-ter-Vehn, and Z. Sheng, “Phase-sensitive terahertz emission from gas targets irradiated by few-cycle laser pulses,” New J. Phys. 10(4), 043001 (2008).
[Crossref]

Opt. Express (1)

Phys. Plasmas (1)

K. Y. Kim, “Generation of coherent terahertz radiation in ultrafast laser-gas interactions,” Phys. Plasmas 16(5), 056706 (2009).
[Crossref]

Phys. Rev. E Stat. Nonlin. Soft Matter Phys. (1)

M. Chen, A. Pukhov, X. Y. Peng, and O. Willi, “Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 78(4), 046406 (2008).
[Crossref] [PubMed]

Phys. Rev. Lett. (6)

I. Babushkin, W. Kuehn, C. Köhler, S. Skupin, L. Bergé, K. Reimann, M. Woerner, J. Herrmann, and T. Elsaesser, “Ultrafast spatiotemporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases,” Phys. Rev. Lett. 105(5), 053903 (2010).
[Crossref] [PubMed]

J. L. Liu and X.-C. Zhang, “Terahertz-radiation-enhanced emission of fluorescence from gas plasma,” Phys. Rev. Lett. 103(23), 235002 (2009).
[Crossref] [PubMed]

P. B. Corkum, “Plasma perspective on strong field multiphoton ionization,” Phys. Rev. Lett. 71(13), 1994–1997 (1993).
[Crossref] [PubMed]

P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62(11), 1259–1262 (1989).
[Crossref] [PubMed]

N. Karpowicz and X.-C. Zhang, “Coherent terahertz echo of tunnel ionization in gases,” Phys. Rev. Lett. 102(9), 093001 (2009).
[Crossref] [PubMed]

J. Dai, X. Xie, and X.-C. Zhang, “Detection of broadband terahertz waves with a laser-induced plasma in gases,” Phys. Rev. Lett. 97(10), 103903 (2006).
[Crossref] [PubMed]

Other (1)

X.-C. Zhang and J. Z. Xu, Introduction to THz Wave Photonics (Springer, 2009).

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Figures (5)

Fig. 1
Fig. 1

Schematic diagram of THz ABCD: a probe laser pulse with center frequency ω 0 and THz pulse with delay Δt are focused into gas medium. The SH emission with THz information from plasma can be collected by lens and a 2 ω 0 narrow band filter, and then detected by a photomultiplier tube (PMT).

Fig. 2
Fig. 2

(a) The real incident THz waveform and spectrum (inset), (b) calculated SH signal waveforms at different probe energies.

Fig. 3
Fig. 3

The plasma density (blue line) at the focus point and the peak SH signal (red line) versus probe pulse energy W .

Fig. 4
Fig. 4

Radiation spectrum of plasma emission at different probe energies: (a) W=30μJ and (b) W=200μJ .

Fig. 5
Fig. 5

(a): Schematic diagrams of the relation between monochromatic laser ( ω 0 ) and THz filed; different TDPD induced by single probe laser pulse and that with THz and reversed THz at different probe pulse energies W , (b) 30μJ , (b) 100μJ and (c) 200μJ .

Equations (1)

Equations on this page are rendered with MathJax. Learn more.

E out (t) dJ(t) dt = 4 e 2 w 0 3 3m E in (t) N e (t),

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