Fig. 1. A schematic view of subcycle EWP interferences. When a molecule is exposed to a two-color laser field, shown as the magenta line, EWPs will be released around the field’s peaks. In a unit cell of the pulse, the EWPs released during each half cycle (t1 and t2) will lead to the same final momentum p, which leads to interference fringes in the momentum space.

Fig. 2. TOF spectrum of $\text{H}_{2}$ interacting with two-color laser fields. In the $\text{H}^{+}$ distribution, there are three regions: ZPD, ATD and Coulomb explosion (CE).

Fig. 3. A slice through a measured electron momentum distribution in the $x{-}z$ plane (laser field polarization along $z$-direction) with a condition $|p_{y}|<0.1$ a.u. and integration over all relative phases of the two-color laser fields. Momentum conservation conditions between one electron and $\text{H}_{2}^{+}$ are applied to the measured data to ensure coincidence selection. To enhance the visibility of structures induced by EWP interferences, a gaussian function is subtracted from the momentum distribution for each relative phase^[19].

Fig. 4. (a) Measured ion momentum distributions of $\text{H}_{2}^{+}$ along the laser polarization direction over the relative phase between the two colors. To enhance the visibility of structures induced by EWP interferences, a gaussian function is subtracted for each relative phase^[19]. (b) The mean value of the momentum distributions of $\text{H}_{2}^{+}$ along the laser polarization direction as a function of the relative phase between the two colors. For comparison the same quantity for $\text{He}^{+}$ is added to the figure. The gray line represents the simulated results using the SFA.

Fig. 5. (a)–(e) Electric fields (red lines) and vector potentials (blue lines) for relative two-color phases 0, $0.25\unicode[STIX]{x1D70B}$, $0.5\unicode[STIX]{x1D70B}$, $0.75\unicode[STIX]{x1D70B}$ and $\unicode[STIX]{x1D70B}$. (f)–(j) Measured electron momentum distributions in the laser polarization plane with subtraction of a gaussian function for the five relative phases. (k)–(o) Momentum distributions along the laser polarization direction with $|p_{x,y}|<0.1$ a.u. for the five relative phases. Vertical gray lines indicate the positions of the ATI peaks.

Fig. 6. Electron momentum distribution correlated with the ATD pathway for a relative two-color phase of 0.