基于分子排列的飞秒光丝及太赫兹产生控制研究
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摘要
太赫兹波是一种波长位于红外和微波之间,频率在0.1-10THZ之间的电磁波,它具有携带信息量丰富、亚皮秒量级脉宽、少振荡周期、低光子能量等特性,在诸多领域有着巨大的应用价值。飞秒激光脉冲光丝能在远程产生较强的太赫兹波,避免了其在传播过程中受到的空气吸收等影响,如何有效控制其强度和偏振是人们普遍关心的一个问题。超短激光脉冲激发线性分子沿着光场偏振方向排列,并且在光场结束后会周期性地恢复,被称为分子的非绝热(无外场)排列。利用非绝热分子排列,可以实现飞秒脉冲成丝以及太赫兹辐射的无外场情况下的全光操控。
本论文工作主要以空气中双原子分子的无外场排列为基础,研究了飞秒光丝在预排列的气体分子中的传输,并且进一步研究了分子排列对光丝中产生的太赫兹辐射的影响。具体包括以下主要内容：
第一,实验上研究了空间平行传输的基波和二次谐波光丝间的相互作用。发现了除了在两脉冲相互作用区域的克尔效应产生的影响以外,由基波光丝预排列的双原子分子也会对后续的二次谐波光丝产生吸引、融合或者排斥等影响,同时这种影响也可以从光丝的荧光强度的变化和光谱的变化中体现出来。通过细致分析,发现了克尔效应引起的自相位调制和交叉相位调制与分子排列引起的交叉聚(散)焦效应是引起这种光丝间相互作用的主要因素。这一研究实现了在微米尺度的空间范围和飞秒量级的时域内的多波长超短脉冲传输的精确控制。
第二,实验上研究了分子无外场排列对由基波和二次谐波组成的双色激光脉冲成丝产生太赫兹辐射的相干控制作用。发现了通过调节泵浦光的延时到不同的排列周期或者调节泵浦光的强度,产生的太赫兹辐射会相应地得到加强或减弱。同时还发现在基波和二次谐波偏振垂直的情况下,产生的太赫兹波偏振也会随着分子的排列周期发生旋转。分子无外场排列诱导的交叉聚(散)焦效应、克尔效应以及等离子体散焦效应等在不同的时空范围都对太赫兹辐射的强度和偏振特性产生了不同的影响。这种针对太赫兹产生的无场操控方法对基于太赫兹辐射的各项研究技术,如空中遥感探测等具有非常重要的作用。
The terahertz (THz) radioation with frequency between 0.1 to 10 THz shows significant applications in many fields by virtue of its preponderance of rich information containing, sub-picosecond pulse duration, few-cycle, low photon energy and so forth. Intense THz radiation can be remotely generated by femtosecond laser pulse induced filamentation, without detrimental absorption attenuation by the presence of water vapor in air. It is quite interesting to effeciently control the strength and polarization of the generated THz especially in an ultrafast all-optical approach. Field-free revivals of impulsive molecular alignment through nonadiabatic rotational Raman excitation can be used to influence the formation of filamentation and thus the simultaneously generated THz radioation.
In this thesis, by using the impulsive alignment of the diatomic molecules in air, we studied the interaction of two spatially parallel lauched femtosecond filaments at different wavelengths and the generation of THz radiation by a two-color pulse. The following studies have been performed:
1. The interaction of two spatially parallel launched femtosecond filaments at the fundamental-wave and second-harmonic frequencies was studied in air. Besides the Kerr effect within the pulse duration, the impulsive alignment of the diatomic molecules in the fundamental-wave filament led to controllable and field-free achievable attraction, fusion, or repulsion of the second-harmonic filament. The molecular-alignment-assisted filament interaction was further confirmed by the fluorescence intensity variation and spectral modulation of the second-harmonic filament at various molecular alignment revivals. This provided us an ultrafast-flexible field-free approach to precisely control the intense ultrashort filaments.
2. All-optical ultrafast control of THz generation from a two-color femtosecond pulse (composed of the fundamental and second-harmonic waves) in air was demonstrated by using impulsive molecular alignment. By tuning its time delay to properly match various molecular alignment revivals, the THz generation from the two-color pulse could be promoted or decreased due to the spatial cross-(de)focusing effect and the alignment-dependent ionization probabilities of the prealigned diatomic molecules in air. For the two-color pulse of orthogonally polarized fundamental and second-harmonic components, the polarization of the generated THz radiation could be controlled by the field-free molecular alignment, which functioned as a transient dynamic wave plate for the THz radiation. The plasma effect on the THz generation of the two-color pulse was also observed, leading to additional amplitude and polarization control of the THz radiation.
本论文工作主要以空气中双原子分子的无外场排列为基础,研究了飞秒光丝在预排列的气体分子中的传输,并且进一步研究了分子排列对光丝中产生的太赫兹辐射的影响。具体包括以下主要内容：
第一,实验上研究了空间平行传输的基波和二次谐波光丝间的相互作用。发现了除了在两脉冲相互作用区域的克尔效应产生的影响以外,由基波光丝预排列的双原子分子也会对后续的二次谐波光丝产生吸引、融合或者排斥等影响,同时这种影响也可以从光丝的荧光强度的变化和光谱的变化中体现出来。通过细致分析,发现了克尔效应引起的自相位调制和交叉相位调制与分子排列引起的交叉聚(散)焦效应是引起这种光丝间相互作用的主要因素。这一研究实现了在微米尺度的空间范围和飞秒量级的时域内的多波长超短脉冲传输的精确控制。
第二,实验上研究了分子无外场排列对由基波和二次谐波组成的双色激光脉冲成丝产生太赫兹辐射的相干控制作用。发现了通过调节泵浦光的延时到不同的排列周期或者调节泵浦光的强度,产生的太赫兹辐射会相应地得到加强或减弱。同时还发现在基波和二次谐波偏振垂直的情况下,产生的太赫兹波偏振也会随着分子的排列周期发生旋转。分子无外场排列诱导的交叉聚(散)焦效应、克尔效应以及等离子体散焦效应等在不同的时空范围都对太赫兹辐射的强度和偏振特性产生了不同的影响。这种针对太赫兹产生的无场操控方法对基于太赫兹辐射的各项研究技术,如空中遥感探测等具有非常重要的作用。
The terahertz (THz) radioation with frequency between 0.1 to 10 THz shows significant applications in many fields by virtue of its preponderance of rich information containing, sub-picosecond pulse duration, few-cycle, low photon energy and so forth. Intense THz radiation can be remotely generated by femtosecond laser pulse induced filamentation, without detrimental absorption attenuation by the presence of water vapor in air. It is quite interesting to effeciently control the strength and polarization of the generated THz especially in an ultrafast all-optical approach. Field-free revivals of impulsive molecular alignment through nonadiabatic rotational Raman excitation can be used to influence the formation of filamentation and thus the simultaneously generated THz radioation.
In this thesis, by using the impulsive alignment of the diatomic molecules in air, we studied the interaction of two spatially parallel lauched femtosecond filaments at different wavelengths and the generation of THz radiation by a two-color pulse. The following studies have been performed:
1. The interaction of two spatially parallel launched femtosecond filaments at the fundamental-wave and second-harmonic frequencies was studied in air. Besides the Kerr effect within the pulse duration, the impulsive alignment of the diatomic molecules in the fundamental-wave filament led to controllable and field-free achievable attraction, fusion, or repulsion of the second-harmonic filament. The molecular-alignment-assisted filament interaction was further confirmed by the fluorescence intensity variation and spectral modulation of the second-harmonic filament at various molecular alignment revivals. This provided us an ultrafast-flexible field-free approach to precisely control the intense ultrashort filaments.
2. All-optical ultrafast control of THz generation from a two-color femtosecond pulse (composed of the fundamental and second-harmonic waves) in air was demonstrated by using impulsive molecular alignment. By tuning its time delay to properly match various molecular alignment revivals, the THz generation from the two-color pulse could be promoted or decreased due to the spatial cross-(de)focusing effect and the alignment-dependent ionization probabilities of the prealigned diatomic molecules in air. For the two-color pulse of orthogonally polarized fundamental and second-harmonic components, the polarization of the generated THz radiation could be controlled by the field-free molecular alignment, which functioned as a transient dynamic wave plate for the THz radiation. The plasma effect on the THz generation of the two-color pulse was also observed, leading to additional amplitude and polarization control of the THz radiation.
引文
1. A. Braun, G. Korn, X. Liu, D. Du, J. Squier, and G. Mourou, "Self-channeling of high-peak-power femtosecond laser pulses in air", Opt. Lett.20,73 (1995).
2. A. Couairon and A. Mysyrowicz, "Femtosecond filamentation in transparent media", Phys. Rep.441,47 (2007).
3. C. C. Cheng, E. M. Wright and J. V. Moloney, "Generation of electromagnetic pulses from plasma channels induced by femtosecond light strings", Phys. Rev. Lett.87,213001 (2001).
4. G. Mechain, S. Tzortzakis, B. Prade, M. Franco, A. Mysyrowicz and B. Leriche, "Calorimetric detection of THz radiation from femtosecond filaments in air", Appl. Phys. B 77,707 (2003).
5. C. D'Amico A. Houard, M. Franco, B. Prade, and A. Mysyrowicz, "Conical forward THz emission from femtosecond-laser-beam filamentation in air", Phys. Rev. Lett.98,235002 (2007).
6. Y. Liu, A. Houard, B. Prade, S. Akturk, and A. Mysyrowicz, "Terahertz radiation source in air based on bifilamentation of femtosecond laser pulses", Phys. Rev. Lett.99,135002 (2007).
7. A. Houard, Y. Liu, B. Prade, V. T. Tikhonchuk, and A. Mysyrowicz, "Strong enhancement of terahertz radiation from laser filaments in air by a static electric field", Phys. Rev. Lett.100,255006 (2008).
8. T. Loffler, F. Jacob, and H. G. Roskos, "Generation of terahertz pulses by photoionization of electrically biased air", Appl. Phys. Lett.77,453 (2009).
9. Y. Chen, T. Wang, C. Marceau, F. Theberge, M. Chateauneuf, J. Dubois, O. Kosareva, and S. L. Chin, "Characterization of terahertz emission from a dc-biased filament in air", Appl. Phys. Lett.95,101101 (2009).
10. D. J. Cook and R. M. Hochstrasser, "Intense terahertz pulses by four-wave rectification in air", Opt. Lett.25,1210 (2000).
11. M. Kreβ, T. Loffler, S. Eden, M. Thomson, and H. G. Roskos, "Terahertz-pulse generation by photoionization of air with laser pulses composed of both fundamental and second-harmonic waves", Opt. Lett.29,1120 (2004).
12. T. Bartel, P. Gaal, K. Reimann, M. Woerner, and T. Elsaesser, "Generation of single-cycle THz transients with high electric-field amplitudes", Opt. Lett.30, 2805 (2005).
13. X. Xie, J. Dai, and X. C. Zhang, "Coherent control of THz wave generation in ambient air", Phys. Rev. Lett.96,075005 (2006).
14. B. Zon, and B. Katsnelson, "Nonresonant scattering of intense light by a molecule", Zh. Eksp. Teor. Fiz.,69,1166 (1975)
15. B. Friedrich and D. Herschbach, "Alignment and trapping of molecules in intense laser fields", Phys. Rev. Lett.74,4623 (1995).
16. S. Banerjee, G. Ravindra Kumar and D. Mathur, "Dynamic and geometric alignment of CS2 in intense laser fields of picosecond and femtosecond duration", Phys. Rev. A 60,3369 (1999).
17. T. Seideman, "Rotational excitation and molecular alignment in intense laser fields", J. Chem. Phys.103,7887 (1995).
18. T. Seideman, "On the dynamics of rotationally broad, spatially aligned wave packets", J. Chem. Phys.115,5965 (2001).
19. M. Machholm and N. E. Henriksen, "Field-free orientation of molecules", Phys. Rev. Lett.87,193001 (2001).
20. P. W. Dooley, I. V. Litvinyuk, K. F. Lee, D. M. Rayner, M.Spanner, D. M. Villeneuve, P. B. Corkum, "Direct imaging of rotational wave-packet dynamics of diatomic molecules", Phys. Rev. A.68,023406 (2003).
21. B. Friedrich and D. Herschbach, "Enhanced orientation of polar molecules by combined electrostatic and nonresonant induced dipole forces", J. Chem. Phys. 111,6157(1999).
22. B. Friedrich and D. Herschbach, "Manipulating molecules via combined static and laser fields", J. Phys. Chem. A,103,10280 (1999).
23. B. Friedrich and D. R. Herschbach, "On the possibility of orienting rotationally cooled polar molecules in an electric field", Z. Phys. D:At. Mol. Clusters 18, 153(1991).
24. D. Daems, S. Guerin, E. Hertz, H. R. Jauslin, B. Lavorel, and O. Faucher, "Field-free two-direction alignment alternation of linear molecules by elliptic laser pulses", Phys. Rev. Lett.95,063005 (2005).
25. I. V. Litvinyuk, K. F. Lee, P. W. Dooley, D. M. Rayner, D. M. Villeneuve, and P. B. Corkum, "Alignment-dependent strong field ionization of molecules", Phys. Rev. Lett.90,233003 (2003).
26. J. Itatani, J. Levesque, D. Zeidler, H. Niikura, H. Pepin, J. C. Kieffer, P. B. Corkum, and D. M. Villeneuve, "Tomographic imaging of molecular orbitals", Nature 432,867 (2004).
27. T. Kanai, S. Minemoto, and H. Sakai, "Quantum interference during high-order harmonic generation from aligned molecules", Nature 435,470 (2005).
28. J. Itatani, D. Zeidler, J. Levesque, M. Spanner, D. M. Villeneuve, and P. B. Corkum, "Controlling high harmonic generation with molecular wave packets", Phys. Rev. Lett.94,123902 (2005).
29. A. Rouzee, V. Renard, S. Guerin, O. Faucher, and B. Lavorel, "Optical gratings induced by field-free alignment of molecules", Phys. Rev. A 75, 013419(2007).
30. F. Calegari, C. Vozzi, S. Gasilov, E. Benedetti, G. Sansone, M. Nisoli, S. De Silvestri, and S. Stagira, "Rotational Raman effects in the wake of optical filamentation", Phys. Rev. Lett.100,123006 (2008).
31. S. Varma, Y.-H. Chen, and H. M. Milchberg, "Trapping and destruction of long-range high-intensity optical filaments by molecular quantum wakes in air", Phys. Rev. Lett.101,205001 (2008).
32. C. Marceau, Y. Chen, F. Theberge, M. Chateauneuf, J. Dubois, and S. L. Chin, "Ultrafast birefringence induced by a femtosecond laser filament in gases", Opt. Lett.34,1417(2009).
33. J. Wu, H. Cai, H. Zeng, and A. Couairon, "Femtosecond filamentation and pulse compression in the wake of molecular alignment", Opt. Lett.33,2593 (2008).
34. H. Cai, J. Wu, H. Li, X. Bai, and H. Zeng, "Elongation offemtosecond filament by molecular alignment in air", Opt. Express 17,21060 (2009).
35. J. Wu, H. Cai, Y. Peng, and H. Zeng, "Controllable supercontinuum generation by the quantum wake of molecular alignment", Phys. Rev. A 79,041404(R) (2009).
36. H. Cai, J. Wu, Y. Peng, and H. Zeng, "Comparison study of supercontinuum generation by molecular alignment of N2 and O2", Opt. Express 17,5822 (2009).
37. H. Cai, J. Wu, X. Bai, H. Pan, and H. Zeng, "Molecular alignment assisted high-energy supercontinuum pulse generation in air", Opt. Lett.35,49 (2010).
38. H. Cai, J. Wu, A. Couairon, and H. Zeng, "Spectral modulation of femtosecond laser pulse induced by molecular alignment revivals", Opt. Lett.34,827 (2009).
39. J. Wu, H. Cai, A. Couairon, and H. Zeng, "Wavelength tuning of a few-cycle laser pulse by molecular alignment in femtosecond filamentation wake", Phys. Rev. A 79,063812 (2009).
40. J. Wu, P. Lu, J. Liu, H. Li, H. Pan, and H. Zeng, "Ultrafast optical imaging by molecular wakes", Appl. Phys. Lett.97,161106 (2010).
41. P. Lu, J. Liu, H. Li, H. Pan, J. Wu, and H. Zeng, "Cross-correlation frequency-resolved optical gating by molecular alignment for ultraviolet femtosecond pulse measurement", Appl. Phys. Lett.97,061101 (2010).
42. J. Liu, Y. Feng, H. Li, P. Lu, H. Pan, J. Wu, and H. Zeng, "Supercontinuum pulse measurement by molecular alignment based cross-correlation frequency resolved optical gating", Opt. Express 19,40 (2011).
43. S. Golubtsov, V. P. Kandidov, and O. G. Kosareva, "Initial phase modulation of a high-power femtosecond laser pulse as a tool for controlling its filamentation and generation of a supercontinuum in air", Quantum Electron.33,525 (2003).
44. G. Mechain, A. Couairon, M. Franco, B. Prade, and A. Mysyrowicz, "Organizing multiple femtosecond filaments in air", Phys. Rev. Lett.93, 035003 (2004).
45. G. Fibich, S. Eisenmann, B. Ilan, and A. Zigler, "Control of multiple filamentation in air", Opt. Lett.29,1772 (2004).
46. F. Theberge, W. Liu, Q. Luo, and S. L. Chin, "Ultrabroadband continuum generated in air (down to 230nm) using ultrashort and intense laser pulses", Appl. Phys. B 80,221 (2005).
47. T-T Xi, X. Lu, and J. Zhang, "Interaction of light filaments generated by femtosecond laser pulses in air", Phys. Rev. Lett.96,025003 (2006).
48. C. Vozzi, F. Calegari, E. Benedetti, J.-P. Caumes, G. Sansone, S. Stagira, M. Nisoli, R. Torres, E. Heesel, N. Kajumba, J. P. Marangos, C. Altucci, and R.Velotta, "Controlling two-center interference in molecular high harmonic generation", Phys. Rev. Lett.95,153902 (2005).
49. J. C. H. Spence, K. Schmidt, J. Wu, G. Hembree, U. Weierstall, B. Doak, and P. Fromme, "Diffraction and imaging from a beam of laseraligned proteins: resolution limits", Acta Crystallogr., Sec. A 61,237 (2005).
50. T. Seideman, "Time-resolved photoelectron angular distributions as a means of studying polyatomic nonadiabatic dynamics", J. Chem. Phys.113,1677 (2000).
51. T. Seideman, "Time-resolved photoelectron angular distributions as a probe of coupled polyatomic dynamics", Phys. Rev. A 64,042504 (2001).
52. R. Boyd, Nonlinear Optics,2nd ed. (Academic Press, New York,2003).
53. J. Ortigoso, M. Rodriguez, M. Gupta, and B. Friedrich, "Time evolution of pendular states created by the interaction of molecular polarizability with a pulsed nonresonant laser field", J. Chem. Phys.110,3870 (1999).
54. C. W. Dirk, W. C. Herndon, F. Cervantes-Lee, H. Selnau, S. Martinez, P. Kalamegham, A. Tan, G. Campos, and M. Velez, "Squarylium dyes:structural factors pertaining to the negative third-order nonlinear optical response", J. Am. Chem. Soc.117,2214(1995).
55. S. Tzortzakis, G. Mechain, G. Patalano, M. Franco, B. Prade, and A. Mysyrowicz, "Concatenation of plasma filaments created in air by femtosecond infrared laser pulses", Appl. Phys. B 76,609 (2003).
56. A. Couairon, G. Mechain, S. Tzortzakis, M. Franco, B. Lamouroux, B. Prade, and A. Mysyrowicz, "Propagation of twin laser pulses in air and concatenation of plasma strings produced by femtosecond infrared filaments", Opt. Commun. 225,177(2003).
57. Y. Ma, X. Lu, T. Xi, Q. Gong, and J. Zhang, "Filamentation of interacting femtosecond laser pulses in air", Appl. Phys. B 93,463 (2008).
58. J. Ripoche, G Grillon, B. Prade, M. Franco, E. Nibbering, R. Lange, and A. Mysyrowicz, "Determination of the time dependence of N2 in air", Opt. Commun.135,310(1997).
59. Y. Chen, C. Marceau, F. Theberge, M. Chateauneuf, J. Dubois, and S. L. Chin, "Polarization separator created by a filament in air", Opt. Lett.33,2731 (2008).
60. R. Bartels, T. Weinacht, N. Wagner, M. Baertschy, C. Greene, M. Murnane, and H. Kapteyn, "Phase modulation of ultrashort light pulses using molecular rotational wave packets", Phys. Rev. Lett.88,013903 (2001).
61. S. Varma, Y.-H. Chen, and H. M. Milchberg, "Quantum molecular lensing of femtosecond laser optical/plasma filaments", Phys. Plasmas 16,056702 (2009).
62. F. Calegari, C. Vozzi, and S. Stagira, "Optical propagation in molecular gases undergoing filamentation-assisted field-free alignment", Phys. Rev. A 79, 023827 (2009).
63. A. C. Bernstein, M. McCormick, G. M. Dyer, J. C. Sanders, and T. Ditmire, Two-beam coupling between filament-forming beams in air", Phys. Rev. Lett. 102,123902(2009).
64. V. Renard, M. Renard, S. Guerin, Y. T. Pashayan, B. Lavorel, O. Faucher, and H. R. Jauslin, "Postpulse molecular alignment measured by a weak field polarization technique", Phys. Rev. Lett.90,153601 (2003).
65. E. T. J. Nibbering, G. Grillon, M. A. Franco, B. S. Prade, and A. Mysyrowicz, "Determination of the inertial contribution to the nonlinear refractive index of air, N2, and O2 by use of unfocused high-intensity femtosecond laser pulses", J. Opt. Soc. Am. B 14,650 (1997).
66. M. D. Thomson, M. Kreβ, T. Loffler, and H. G. Roskos, "Broadband THz emission from gas plasmas induced by femtosecond optical pulses:From fundamentals to applications", Laser & Photon. Rev.1,349 (2007).
67. D.W. Schumacher and P. H. Bucksbaum, "Phase dependence of intense-field ionization", Phys. Rev. A 54,4271 (1996).
68. M. Kreβ, T. Loffler, M. D. Thomson, R. Dorner, H. Gimpel, K. Zrost, T. Ergler, R. Moshammer, U. Morgner, J. Ullrich, and H. G. Roskos, "Determination of the carrier-envelope phase of few-cycle laser pulses with terahertz-emission spectroscopy", Nature Phys.2,327 (2006).
69. X. Xie, J. Xu, J. Dai, and X. C. Zhang, "Enhancement of terahertz wave generation from laser induced plasma", Appl. Phys. Lett.90,141104 (2007).
70. 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, 4577 (2007).
71. K. Y. Kim, A. J. Taylor, J. H. Glownia and G. Rodriguez, "Coherent control of terahertz supercontinuum generation in ultrafast laser-gas interactions", Nature photon.2,605 (2008)
72. P. C. M. Planken, H. Nienhuys, H. J. Bakker and T. Wenckebach, "Measurement and calculation of the orientation dependence of terahertz pulse detection in ZnTe", J. Opt. Soc. Am. B 18,313 (2001).
73. H. Stapelfeldt and T. Seideman, "Aligning molecules with strong laser pulses", Rev. Mod. Phys.75,543 (2003).
74. H. Wen and A. M. Lindenberg, "Coherent terahertz polarization control through manipulation of electron trajectories", Phys. Rev. Lett.103,023902 (2009).
75. J. Dai, N. Karpowicz, and X. C. Zhang, "Coherent polarization control of terahertz waves generated from two-color laser-induced gas plasma", Phys. Rev. Lett.103,023001 (2009).
2. A. Couairon and A. Mysyrowicz, "Femtosecond filamentation in transparent media", Phys. Rep.441,47 (2007).
3. C. C. Cheng, E. M. Wright and J. V. Moloney, "Generation of electromagnetic pulses from plasma channels induced by femtosecond light strings", Phys. Rev. Lett.87,213001 (2001).
4. G. Mechain, S. Tzortzakis, B. Prade, M. Franco, A. Mysyrowicz and B. Leriche, "Calorimetric detection of THz radiation from femtosecond filaments in air", Appl. Phys. B 77,707 (2003).
5. C. D'Amico A. Houard, M. Franco, B. Prade, and A. Mysyrowicz, "Conical forward THz emission from femtosecond-laser-beam filamentation in air", Phys. Rev. Lett.98,235002 (2007).
6. Y. Liu, A. Houard, B. Prade, S. Akturk, and A. Mysyrowicz, "Terahertz radiation source in air based on bifilamentation of femtosecond laser pulses", Phys. Rev. Lett.99,135002 (2007).
7. A. Houard, Y. Liu, B. Prade, V. T. Tikhonchuk, and A. Mysyrowicz, "Strong enhancement of terahertz radiation from laser filaments in air by a static electric field", Phys. Rev. Lett.100,255006 (2008).
8. T. Loffler, F. Jacob, and H. G. Roskos, "Generation of terahertz pulses by photoionization of electrically biased air", Appl. Phys. Lett.77,453 (2009).
9. Y. Chen, T. Wang, C. Marceau, F. Theberge, M. Chateauneuf, J. Dubois, O. Kosareva, and S. L. Chin, "Characterization of terahertz emission from a dc-biased filament in air", Appl. Phys. Lett.95,101101 (2009).
10. D. J. Cook and R. M. Hochstrasser, "Intense terahertz pulses by four-wave rectification in air", Opt. Lett.25,1210 (2000).
11. M. Kreβ, T. Loffler, S. Eden, M. Thomson, and H. G. Roskos, "Terahertz-pulse generation by photoionization of air with laser pulses composed of both fundamental and second-harmonic waves", Opt. Lett.29,1120 (2004).
12. T. Bartel, P. Gaal, K. Reimann, M. Woerner, and T. Elsaesser, "Generation of single-cycle THz transients with high electric-field amplitudes", Opt. Lett.30, 2805 (2005).
13. X. Xie, J. Dai, and X. C. Zhang, "Coherent control of THz wave generation in ambient air", Phys. Rev. Lett.96,075005 (2006).
14. B. Zon, and B. Katsnelson, "Nonresonant scattering of intense light by a molecule", Zh. Eksp. Teor. Fiz.,69,1166 (1975)
15. B. Friedrich and D. Herschbach, "Alignment and trapping of molecules in intense laser fields", Phys. Rev. Lett.74,4623 (1995).
16. S. Banerjee, G. Ravindra Kumar and D. Mathur, "Dynamic and geometric alignment of CS2 in intense laser fields of picosecond and femtosecond duration", Phys. Rev. A 60,3369 (1999).
17. T. Seideman, "Rotational excitation and molecular alignment in intense laser fields", J. Chem. Phys.103,7887 (1995).
18. T. Seideman, "On the dynamics of rotationally broad, spatially aligned wave packets", J. Chem. Phys.115,5965 (2001).
19. M. Machholm and N. E. Henriksen, "Field-free orientation of molecules", Phys. Rev. Lett.87,193001 (2001).
20. P. W. Dooley, I. V. Litvinyuk, K. F. Lee, D. M. Rayner, M.Spanner, D. M. Villeneuve, P. B. Corkum, "Direct imaging of rotational wave-packet dynamics of diatomic molecules", Phys. Rev. A.68,023406 (2003).
21. B. Friedrich and D. Herschbach, "Enhanced orientation of polar molecules by combined electrostatic and nonresonant induced dipole forces", J. Chem. Phys. 111,6157(1999).
22. B. Friedrich and D. Herschbach, "Manipulating molecules via combined static and laser fields", J. Phys. Chem. A,103,10280 (1999).
23. B. Friedrich and D. R. Herschbach, "On the possibility of orienting rotationally cooled polar molecules in an electric field", Z. Phys. D:At. Mol. Clusters 18, 153(1991).
24. D. Daems, S. Guerin, E. Hertz, H. R. Jauslin, B. Lavorel, and O. Faucher, "Field-free two-direction alignment alternation of linear molecules by elliptic laser pulses", Phys. Rev. Lett.95,063005 (2005).
25. I. V. Litvinyuk, K. F. Lee, P. W. Dooley, D. M. Rayner, D. M. Villeneuve, and P. B. Corkum, "Alignment-dependent strong field ionization of molecules", Phys. Rev. Lett.90,233003 (2003).
26. J. Itatani, J. Levesque, D. Zeidler, H. Niikura, H. Pepin, J. C. Kieffer, P. B. Corkum, and D. M. Villeneuve, "Tomographic imaging of molecular orbitals", Nature 432,867 (2004).
27. T. Kanai, S. Minemoto, and H. Sakai, "Quantum interference during high-order harmonic generation from aligned molecules", Nature 435,470 (2005).
28. J. Itatani, D. Zeidler, J. Levesque, M. Spanner, D. M. Villeneuve, and P. B. Corkum, "Controlling high harmonic generation with molecular wave packets", Phys. Rev. Lett.94,123902 (2005).
29. A. Rouzee, V. Renard, S. Guerin, O. Faucher, and B. Lavorel, "Optical gratings induced by field-free alignment of molecules", Phys. Rev. A 75, 013419(2007).
30. F. Calegari, C. Vozzi, S. Gasilov, E. Benedetti, G. Sansone, M. Nisoli, S. De Silvestri, and S. Stagira, "Rotational Raman effects in the wake of optical filamentation", Phys. Rev. Lett.100,123006 (2008).
31. S. Varma, Y.-H. Chen, and H. M. Milchberg, "Trapping and destruction of long-range high-intensity optical filaments by molecular quantum wakes in air", Phys. Rev. Lett.101,205001 (2008).
32. C. Marceau, Y. Chen, F. Theberge, M. Chateauneuf, J. Dubois, and S. L. Chin, "Ultrafast birefringence induced by a femtosecond laser filament in gases", Opt. Lett.34,1417(2009).
33. J. Wu, H. Cai, H. Zeng, and A. Couairon, "Femtosecond filamentation and pulse compression in the wake of molecular alignment", Opt. Lett.33,2593 (2008).
34. H. Cai, J. Wu, H. Li, X. Bai, and H. Zeng, "Elongation offemtosecond filament by molecular alignment in air", Opt. Express 17,21060 (2009).
35. J. Wu, H. Cai, Y. Peng, and H. Zeng, "Controllable supercontinuum generation by the quantum wake of molecular alignment", Phys. Rev. A 79,041404(R) (2009).
36. H. Cai, J. Wu, Y. Peng, and H. Zeng, "Comparison study of supercontinuum generation by molecular alignment of N2 and O2", Opt. Express 17,5822 (2009).
37. H. Cai, J. Wu, X. Bai, H. Pan, and H. Zeng, "Molecular alignment assisted high-energy supercontinuum pulse generation in air", Opt. Lett.35,49 (2010).
38. H. Cai, J. Wu, A. Couairon, and H. Zeng, "Spectral modulation of femtosecond laser pulse induced by molecular alignment revivals", Opt. Lett.34,827 (2009).
39. J. Wu, H. Cai, A. Couairon, and H. Zeng, "Wavelength tuning of a few-cycle laser pulse by molecular alignment in femtosecond filamentation wake", Phys. Rev. A 79,063812 (2009).
40. J. Wu, P. Lu, J. Liu, H. Li, H. Pan, and H. Zeng, "Ultrafast optical imaging by molecular wakes", Appl. Phys. Lett.97,161106 (2010).
41. P. Lu, J. Liu, H. Li, H. Pan, J. Wu, and H. Zeng, "Cross-correlation frequency-resolved optical gating by molecular alignment for ultraviolet femtosecond pulse measurement", Appl. Phys. Lett.97,061101 (2010).
42. J. Liu, Y. Feng, H. Li, P. Lu, H. Pan, J. Wu, and H. Zeng, "Supercontinuum pulse measurement by molecular alignment based cross-correlation frequency resolved optical gating", Opt. Express 19,40 (2011).
43. S. Golubtsov, V. P. Kandidov, and O. G. Kosareva, "Initial phase modulation of a high-power femtosecond laser pulse as a tool for controlling its filamentation and generation of a supercontinuum in air", Quantum Electron.33,525 (2003).
44. G. Mechain, A. Couairon, M. Franco, B. Prade, and A. Mysyrowicz, "Organizing multiple femtosecond filaments in air", Phys. Rev. Lett.93, 035003 (2004).
45. G. Fibich, S. Eisenmann, B. Ilan, and A. Zigler, "Control of multiple filamentation in air", Opt. Lett.29,1772 (2004).
46. F. Theberge, W. Liu, Q. Luo, and S. L. Chin, "Ultrabroadband continuum generated in air (down to 230nm) using ultrashort and intense laser pulses", Appl. Phys. B 80,221 (2005).
47. T-T Xi, X. Lu, and J. Zhang, "Interaction of light filaments generated by femtosecond laser pulses in air", Phys. Rev. Lett.96,025003 (2006).
48. C. Vozzi, F. Calegari, E. Benedetti, J.-P. Caumes, G. Sansone, S. Stagira, M. Nisoli, R. Torres, E. Heesel, N. Kajumba, J. P. Marangos, C. Altucci, and R.Velotta, "Controlling two-center interference in molecular high harmonic generation", Phys. Rev. Lett.95,153902 (2005).
49. J. C. H. Spence, K. Schmidt, J. Wu, G. Hembree, U. Weierstall, B. Doak, and P. Fromme, "Diffraction and imaging from a beam of laseraligned proteins: resolution limits", Acta Crystallogr., Sec. A 61,237 (2005).
50. T. Seideman, "Time-resolved photoelectron angular distributions as a means of studying polyatomic nonadiabatic dynamics", J. Chem. Phys.113,1677 (2000).
51. T. Seideman, "Time-resolved photoelectron angular distributions as a probe of coupled polyatomic dynamics", Phys. Rev. A 64,042504 (2001).
52. R. Boyd, Nonlinear Optics,2nd ed. (Academic Press, New York,2003).
53. J. Ortigoso, M. Rodriguez, M. Gupta, and B. Friedrich, "Time evolution of pendular states created by the interaction of molecular polarizability with a pulsed nonresonant laser field", J. Chem. Phys.110,3870 (1999).
54. C. W. Dirk, W. C. Herndon, F. Cervantes-Lee, H. Selnau, S. Martinez, P. Kalamegham, A. Tan, G. Campos, and M. Velez, "Squarylium dyes:structural factors pertaining to the negative third-order nonlinear optical response", J. Am. Chem. Soc.117,2214(1995).
55. S. Tzortzakis, G. Mechain, G. Patalano, M. Franco, B. Prade, and A. Mysyrowicz, "Concatenation of plasma filaments created in air by femtosecond infrared laser pulses", Appl. Phys. B 76,609 (2003).
56. A. Couairon, G. Mechain, S. Tzortzakis, M. Franco, B. Lamouroux, B. Prade, and A. Mysyrowicz, "Propagation of twin laser pulses in air and concatenation of plasma strings produced by femtosecond infrared filaments", Opt. Commun. 225,177(2003).
57. Y. Ma, X. Lu, T. Xi, Q. Gong, and J. Zhang, "Filamentation of interacting femtosecond laser pulses in air", Appl. Phys. B 93,463 (2008).
58. J. Ripoche, G Grillon, B. Prade, M. Franco, E. Nibbering, R. Lange, and A. Mysyrowicz, "Determination of the time dependence of N2 in air", Opt. Commun.135,310(1997).
59. Y. Chen, C. Marceau, F. Theberge, M. Chateauneuf, J. Dubois, and S. L. Chin, "Polarization separator created by a filament in air", Opt. Lett.33,2731 (2008).
60. R. Bartels, T. Weinacht, N. Wagner, M. Baertschy, C. Greene, M. Murnane, and H. Kapteyn, "Phase modulation of ultrashort light pulses using molecular rotational wave packets", Phys. Rev. Lett.88,013903 (2001).
61. S. Varma, Y.-H. Chen, and H. M. Milchberg, "Quantum molecular lensing of femtosecond laser optical/plasma filaments", Phys. Plasmas 16,056702 (2009).
62. F. Calegari, C. Vozzi, and S. Stagira, "Optical propagation in molecular gases undergoing filamentation-assisted field-free alignment", Phys. Rev. A 79, 023827 (2009).
63. A. C. Bernstein, M. McCormick, G. M. Dyer, J. C. Sanders, and T. Ditmire, Two-beam coupling between filament-forming beams in air", Phys. Rev. Lett. 102,123902(2009).
64. V. Renard, M. Renard, S. Guerin, Y. T. Pashayan, B. Lavorel, O. Faucher, and H. R. Jauslin, "Postpulse molecular alignment measured by a weak field polarization technique", Phys. Rev. Lett.90,153601 (2003).
65. E. T. J. Nibbering, G. Grillon, M. A. Franco, B. S. Prade, and A. Mysyrowicz, "Determination of the inertial contribution to the nonlinear refractive index of air, N2, and O2 by use of unfocused high-intensity femtosecond laser pulses", J. Opt. Soc. Am. B 14,650 (1997).
66. M. D. Thomson, M. Kreβ, T. Loffler, and H. G. Roskos, "Broadband THz emission from gas plasmas induced by femtosecond optical pulses:From fundamentals to applications", Laser & Photon. Rev.1,349 (2007).
67. D.W. Schumacher and P. H. Bucksbaum, "Phase dependence of intense-field ionization", Phys. Rev. A 54,4271 (1996).
68. M. Kreβ, T. Loffler, M. D. Thomson, R. Dorner, H. Gimpel, K. Zrost, T. Ergler, R. Moshammer, U. Morgner, J. Ullrich, and H. G. Roskos, "Determination of the carrier-envelope phase of few-cycle laser pulses with terahertz-emission spectroscopy", Nature Phys.2,327 (2006).
69. X. Xie, J. Xu, J. Dai, and X. C. Zhang, "Enhancement of terahertz wave generation from laser induced plasma", Appl. Phys. Lett.90,141104 (2007).
70. 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, 4577 (2007).
71. K. Y. Kim, A. J. Taylor, J. H. Glownia and G. Rodriguez, "Coherent control of terahertz supercontinuum generation in ultrafast laser-gas interactions", Nature photon.2,605 (2008)
72. P. C. M. Planken, H. Nienhuys, H. J. Bakker and T. Wenckebach, "Measurement and calculation of the orientation dependence of terahertz pulse detection in ZnTe", J. Opt. Soc. Am. B 18,313 (2001).
73. H. Stapelfeldt and T. Seideman, "Aligning molecules with strong laser pulses", Rev. Mod. Phys.75,543 (2003).
74. H. Wen and A. M. Lindenberg, "Coherent terahertz polarization control through manipulation of electron trajectories", Phys. Rev. Lett.103,023902 (2009).
75. J. Dai, N. Karpowicz, and X. C. Zhang, "Coherent polarization control of terahertz waves generated from two-color laser-induced gas plasma", Phys. Rev. Lett.103,023001 (2009).