[1] [1] Goulielmakis E, Schultze M, Hofstetter M, et al. Single-cycle nonlinear optics [J]. Science, 2008, 320(5883): 1614-1617.

[5] [5] Corkum P B. Plasma perspective on strong field multiphoton ionization [J]. Physical Review Letters, 1993, 71(13): 1994-1997.

[6] [6] Zeng Z, Cheng Y, Song X, et al. Generation of an extreme ultraviolet supercontinuum in a two-color laser field [J]. Physical Review Letters, 2007, 98(20): 203901.

[7] [7] Takahashi E J, Lan P, Mücke O D, et al. Attosecond nonlinear optics using gigawatt-scale isolated attosecond pulses [J]. Nature Communications, 2013, 4: 2691.

[8] [8] Takahashi E J, Lan P, Mücke O D, et al. Infrared two-color multicycle laser field synthesis for generating an intense attosecond pulse [J]. Physical Review Letters, 2010, 104: 233901.

[9] [9] Wei P F, Miao J, Zeng Z N, et al. Selective enhancement of a single harmonic emission in a driving laser field with subcycle waveform control [J]. Physical Review Letters, 2013, 110: 233903.

[10] [10] Feng L Q, Chu T S. Generation of an isolated sub-40-as pulse using two-color laser pulses: Combined chirp effects [J]. Physical Review A, 2011, 84(5): 053853.

[11] [11] Chang Z H. Chirp of the single attosecond pulse generated by a polarization gating [J]. Physical Review A, 2005, 71(2): 023813.

[12] [12] Feng L Q, Liu H. Generation of the ultrabroad bandwidth with keV by three-color low intense mid-infrared inhomogeneous pulse [J]. Optics and Laser Technology, 2016, 81: 7-13.

[13] [13] Feng L Q. Molecular harmonic extension and enhancement from H+2 ions in the presence of spatially inhomogeneous fields [J]. Physical Review A, 2015, 92(5): 053832.

[14] [14] Feng L Q, Li Y, Meng F S, et al. High-order harmonic and attosecond pulse generations from Rydberg state driven by the spatially inhomogeneous field [J]. Modern Physics Letters B, 2017, 31(4): 1750029.

[15] [15] Feng L Q, Chu T S. Nuclear signatures on the molecular harmonic emission and the attosecond pulse generation [J]. Journal of Chemical Physics, 2012, 13(5): 054102.

[16] [16] Feng L Q, Chu T S. Intensity improvement in the attosecond pulse generation with the coherent superposition initial state [J]. Physics Letters A, 2012, 376: 1523-1530.

[17] [17] Lu R F, Zhang P Y, Han K L. Attosecond-resolution quantum dynamics calculations for atoms and molecules in strong laser fields [J]. Physical Review E, 2008, 77(6): 066701.

[18] [18] Antoine P, Piraux B, Maquet A. Time profile of harmonics generated by a single atom in a strong electromagnetic field [J]. Physical Review A, 1995, 51(3): R1750-R1753.

[19] [19] Mairesse Y, Bohan A D, Frasinski L J, et al. Attosecond synchronization of high-harmonic soft x-rays [J]. Science, 2003, 302(5650): 1540-1543.

[20] [20] Jin C, Wang G L, Wei H, et al. Waveforms for optimal sub-keV high-order harmonics with synthesized two-or three-colour laser fields [J]. Nature Communications, 2014, 5: 4003.