Photoelectron holographic (PH) interference is one of the research frontiers in strong-field physics, especially in forward- and backward-scattering holography. Achieving control over the specific type of hologram—whether forward- or backward-scattering dominated—has, however, remained challenging. In this study, we demonstrate that the photoelectron momentum distribution (PMD) of $H_2$ molecules in parallel linearly polarized laser pulses can be precisely controlled by tuning the amplitude ratio $\beta$ between the fundamental and second-harmonic (SH) pulses. We show that varying $\beta$ steers the dynamics from dominant forward scattering to backward scattering, transforming the interference pattern from a right-pointing spiderlike structure to a fishbonelike structure on both sides. A key finding is the emergence of a distinct specklelike structure within the fishbonelike structure at $\beta =-0.07$. Through quantum-trajectory analysis, we identify that these speckles originate from intercycle interference between electron wave packets released in adjacent optical cycles. This provides a clear signature to identify the role of long-term coherent accumulation in holographic structures. Our results not only provide a practical method to selectively generate desired holograms—e.g., backward-scattering holography for $\beta$ between 0 and $-0.15$—but also open a window to observe subcycle and multicycle interference effects in strong-field ionization.

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• Electronic excitation & ionization
• Light-matter interaction
• Atoms
• Molecules
• Semiclassical methods