Dynamic control of on-site potentials is key to controlling band structures and light transport in lattice systems. Here, we demonstrate a dynamically tunable binary photonic lattice in a four-level atomic system, formed by superimposing two standing-wave fields with a 1:2 period ratio, under far-detuned electromagnetically induced transparency. In this regime, absorption is strongly suppressed, and the refractive-index response is dominated by its dispersive component. By tuning the laser frequency detuning, we continuously reshape the refractive-index contrast between two sublattices, enabling all-optical control of the on-site potentials. This control drives a clear reconfiguration of the optical modes, whereby the probe field shifts its concentration in real space, accompanied by an alternating distribution of reciprocal-space energy between the first- and second-order diffraction channels. Our results demonstrate a low-loss route to on-demand mode reconfiguration, opening new possibilities for programmable light steering and reconfigurable photonic functions in atomic media.

Spatiotemporal mode-locked (STML) fiber lasers have garnered significant interest in recent years for their unique ability to generate high-energy ultrashort pulses while simultaneously supporting complex transverse field structures. In particular, the formation of soliton molecules opens new avenues for ultrafast signal processing, high-bit-rate optical communications, and precision metrology. In this work, we presented a mode-resolved investigation into the birth, temporal evolution, and nonlinear dynamics of multiple soliton molecules in an all-fiber STML laser. Additionally, our mode-resolved analysis revealed that the transverse modes evolved synchronously during soliton-molecule formation while maintaining a relatively stable modal energy distribution. We further observed that both pulse spacing and relative phase gradually converged to constant values after a transient stage, indicating the formation of stable soliton molecules sustained by the balance among dispersion, nonlinearity, and gain-loss dynamics. Our study not only advances fundamental understanding of multi-soliton physics in complex laser cavities but also provides a numerical basis for engineering tailored spatiotemporal soliton molecules with controllable molecular order, spacing, and stability.