Fig. 1. Vector potential of linearly and circularly polarized Gaussian pulses with different chirp parameters varying with time when central carrier frequency is ω0=2a.u.. (a) Linear polarization; (b) circular polarization

Fig. 2. Influences of chirp and polarization of pulse on energy spectrum and AC Stark energy shift. (a) Photoelectron energy spectra for ionization of atomic hydrogen; (b) E0(t) varying with time; (c) E0(t)+ω(t) varying with time

Fig. 3. Instantaneous ionization rate and occupation probability amplitude of ground state varying with time. (a) Instantaneous ionization rate; (b) occupation probability amplitude

Fig. 4. Photoelectron energy spectra and time-varying ground state occupation probability amplitude. (a) Photoelectron energy spectra; (b) ground state occupation probability amplitude