Harmonic spectra from the initial state p₊ (left column) and p₋ (right column) states. The red solid line and the blue dashed line represent the x component and the y component, respectively. (a) and (c) 30th–90th orders. The insets show the overlook of the whole harmonic spectra structure. (b) and (d) The phase differences between x and y components. The red solid circles and the blue solid squares represent 3n+1 and 3n+2 orders, respectively. The parameters of the two laser pulses are λ 1 = 2 λ 2 = 1600 nm and I 1 = I 2 = 0.5 × 10 14 W / cm 2 .