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.
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.
We investigate spin wave (SW) spectra in two-dimensional (2D) magnonic quasicrystals (MQCs) based on Ammann−Beenker (AB) tiling using micromagnetic simulations. The AB MQC structure is realized as an antidot lattice (ADL) etched into a thin Permalloy (Py) strip, generated via projection from a four-dimensional (4D) hypercube onto a 2D plane within a selection window in perpendicular space. Our simulations reveal SW dispersion with distinct circular ring patterns in frequency slices. The centers of these rings coincide with high-intensity diffraction points predicted by the higher-dimensional projection method, and their intensity correlates with corresponding diffraction peaks, confirming origins from Bragg reflection. The spectra exhibit numerous band gaps and fractal characteristics inherent to quasiperiodicity. Crucially, band gap tuning can be achieved by scaling the perpendicular-space selection window, which modifies diffraction intensities and thereby adjusts the SW band structure. This introduces a new design degree of freedom for reconfigurable magnonic devices. Our results demonstrate the effectiveness of the higher-dimensional projection method for analyzing MQC SW dispersion and highlight the potential of quasiperiodic modulation in engineering SW spectra for low-cost, reconfigurable spintronic applications.
Stimulated Brillouin scattering (SBS) has emerged as a fundamental nonlinear process in integrated photonics, enabling advanced coherent signal processing, narrow-linewidth lasers, and ultra-high-resolution sensing. However, harnessing SBS at the chip scale presents inherent challenges, primarily originating from weak optomechanical interactions and short phonon lifetimes. This review provides a comprehensive and systematic overview of the latest advances in enhancing on-chip SBS. For the first time, we categorize the enhancement approaches into three interrelated pathways: waveguide geometry engineering (exploiting radiation pressure and phonon confinement), material-core optimization (ranging from chalcogenides to piezoelectric materials), and hybrid dynamic control schemes (such as phonon injection and electro-optic tuning). We further explore the frontier applications of engineered on-chip SBS in microwave photonics, quantum information processing, and optomechanical sensing. Finally, we offer perspectives on future directions and remaining challenges toward realizing scalable and multifunctional Brillouin photonic integrated circuits. This work serves as a roadmap for unlocking the full potential of Brillouin interactions in next-generation integrated systems.
Acoustic vortices carrying orbital angular momentum, often generated using metagratings, provide an effective approach for wavefront engineering, particle manipulation, and underwater information transfer. However, most existing acoustic metagratings rely on fixed structural configurations, which inherently restrict their tunability and multifunctionality. Here, we propose a three-dimensional reconfigurable reflective acoustic metagrating for dynamic manipulation of vortex fields. The device consists of two gradient-depth air-groove supercells, in which the reflection response can be actively reconfigured by tuning the depth of paired grooves. Based on a generalized conservation principle of topological charge in metagrating diffraction, we demonstrate controllable conversion of incident acoustic vortex beams into reflected vortex states with different diffraction channels. In particular, near-perfect switching between anomalous reflection and specular reflection is achieved with high conversion efficiency. In addition to structural reconfiguration, frequency-dependent modulation provides an additional degree of freedom for dynamically tailoring the reflected vortex field. Our results reveal a simple yet robust mechanism for tunable vortex-beam reflection and offer a compact platform for multifunctional acoustic devices, with potential extensions to other wave systems such as electromagnetic and elastic waves.
