(a) The electric field of the laser pulses with the combination of ω/1.5ω laser fields in two cycles, I_x = 5 × 10¹⁴ W/cm², I_y = 5 × 10¹⁴ W/cm², λ_x = 1200 nm, λ_y = 800 nm, O is the origin of E_x–E_y, A, A′, B, B′, C, C′ (D, D′) denote the ionization (return) moments of the electron, the arrows mean the trend of electric field; (b) the time–frequency distribution of the HHG corresponding to the case of panel (a); (c) and (d) the time-dependent electron wave packets probability density of x, y axes, respectively. The white line means that classical computations show that the excursion of the electron trajectories in the continuum is characterized by a distance x₀ = E₀/ω².