[1] [1] AGOSTINI P, FABRE F, MAINFRAY G, et al. Free-free transitions following six-photon ionization of xenon atoms ［J］. Physical Review Letters, 1979, D42(17): 1127-1130.

[2] [2] FITTINGHOFF D N, BOLTON P R, CHANG B, et al. Observation of nonsequential double ionization of helium with optical tunneling ［J］. Physical Review Letters, 1992, 69(18): 2642-2645.

[3] [3] XU C Y, FENG L Q, QIAO Y, et al. Pulse duration dependence of harmonic yield of H2+ and its isotopic molecule ［J］. The European Physical Journal, 2020, D74(7): 139.

[4] [4] FRASINSKI L J, CODLING K, HATHERLY P, et al. Femtosecond dynamics of multielectron dissociative ionization by use of a picose-cond laser ［J］. Physical Review Letters, 1987, 58(23): 2424-2427.

[5] [5] LI L, ZHENG M, FENG R L Q, et al. Waveform control in generations of intense water window attosecond pulses via multi-color combined field ［J］. International Journal of Modern Physics, 2019, B33(13): 1950130.

[6] [6] LIU H, FENG L Q. Mid-infrared field phase measurement and a-ttosecond pulse generation ［J］. Laser Technology, 2017, 41(2): 151-158 (in Chinese) .

[7] [7] FENG L Q, LI Y, LIU H. High intensity attosecond pulse generation by the improved multi-cycle polarization gating technology ［J］. Laser Technology, 2018, 42(4): 451-456 (in Chinese).

[8] [8] L’HUILLIER A, BALCOU P. High-order harmonic generation in rare gases with a 1ps 1053nm laser ［J］. Physical Review Letters, 1993, 70(6): 774-777.

[9] [9] LI Y, FENG L Q, QIAO Y. Selective enhancement of single-order and two-order harmonics from He atom via two-color and three-color laser fields ［J］. Chemical Physics, 2019, 527(12): 110497.

[10] [10] SANSONE G, BENEDETTI E, CALEGARI F, et al. Isolated single-cycle attosecond pulses ［J］. Science, 2006, 314(5798): 443-446.

[11] [11] CORKUM P B. Plasma perspective on strong field multiphoton ionization ［J］. Physical Review Letters, 1993, 71(13): 1994-1997.

[12] [12] FENG L Q. Molecular harmonic extension and enhancement from H2+ ions in the presence of spatially inhomogeneous fields ［J］. Physical Review, 2015, A92(5): 053832.

[13] [13] YUAN Q, FENG L Q, LIU H. Half-cycle waveform control for ge-nerating ultra-wide harmonic spectral plateau ［J］. Laser Technology, 2021, 45(4): 463-469 (in Chinese).

[14] [14] LI Y, FENG R L Q, QIAO Y. Improvement of harmonic spectra from superposition of initial state driven by homogeneous and inhomogeneous combined field ［J］. Canadian Journal of Physics, 2020, 98(1): 198-209.

[15] [15] LI Y, FENG L Q. Improvement of harmonic cutoff energy and intensity by using chirped-UV combined field ［J］. Chinese Journal of Quantum Electronics, 2019, 36(6): 738-744 (in Chinese).

[16] [16] LIU H, LI Y, YAO Zh, et al. Chirp pulse control on harmonic cutoff and harmonic intensity ［J］. Laser Technology, 2017, 41(5): 708-711 (in Chinese).

[17] [17] FENG L Q, CHU T S. Generation of an isolated sub-40as pulse using two-color laser pulses: Combined chirp effects ［J］. Physical Review, 2011, A84(5): 053853.

[18] [18] FENG L Q, LI Y. Generation of attosecond pulses from He atom driven by UV-chirped laser beam ［J］. Laser Technology, 2019, 43(5): 629-634 (in Chinese).

[19] [19] 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, 2008, E77(6): 066701.

[20] [20] FENG L Q, McCAIN J, QIAO Y. Half-cycle waveform control for producing a broad and intense harmonic spectral continuum and an isolated attosecond pulse ［J］. Laser Physics, 2021, 31(5): 055301.