Figure 1

(Color online) Measured 23rd harmonic yield (solid line) from aligned ${\text{CO}}_2$ molecules and calculated alignment parameter $⟨{\text{cos}}^2\theta ⟩$ (dashed line) as functions of the pump-probe delay time. The temporal modulation of the harmonic intensity reverse-matches the alignment.Reuse & Permissions

Figure 2

(Color online) Normalized harmonic intensities $\left(f/f_0\right)$ for the 17th–31st order harmonics at two pump-probe delays: 21.1 (open squares) and 21.9 ps (solid circles) for two probe laser intensities: (a) $2.4\times {10}^{14}$ and (b) $1.9\times {10}^{14}\text{W}/{\text{cm}}^2$. The harmonic intensity is normalized to that of an isotropic distribution of ${\text{CO}}_2$ (without using the pump laser pulses) subjected to the same probe laser field. With the higher probe laser intensity (a), the 17th–27th harmonic signals at 21.1 ps are weaker than those at 21.9 ps (inverted with respect to molecular alignment). When the probe laser intensity decreases to $1.9\times {10}^{14}\text{W}/{\text{cm}}^2$, the reversed harmonic orders are the 17th–25th orders.Reuse & Permissions

Figure 3

(Color online) Time evolution of the 25th order harmonic intensity from aligned ${\text{CO}}_2$ at around half revival for the probe laser intensities of (a) $1.6\times {10}^{14}$, (b) $1.9\times {10}^{14}$, (c) $2.1\times {10}^{14}$, and (d) $2.4\times {10}^{14}\text{W}/{\text{cm}}^2$. Also shown is the calculated alignment parameter $⟨{\text{cos}}^2\theta ⟩$ (dashed line).Reuse & Permissions

Figure 4

(Color online) Calculated normalized intensities $\left(f/f_0\right)$ of the 25th order harmonic emission at two pump-probe delays: 21.1 (open squares) and 21.9 ps (solid circles) as functions of the probe laser intensities from $1.2\times {10}^{14}$ to $2.4\times {10}^{14}\text{W}/{\text{cm}}^2$. The calculations were carried out by (a) considering and (b) not considering the ground state depletion factor.Reuse & Permissions