Dispersionless coupling control enabled by artificial gauge fields for dense waveguide arrays and arbitrary-ratio power splitters

Evanescent coupling is central to integrated photonics, enabling essential functions such as power splitting, routing, and beamforming, yet it also fundamentally limits photonic integration density through crosstalk and strong wavelength dispersion. Achieving broadband suppression and control of coupling in densely packed waveguide arrays remains a long-standing challenge. Here, we present an artificial gauge field (AGF)-based strategy that enables both wavelength-insensitive coupling suppression and dispersionless, arbitrary-ratio power splitting on a silicon-on-insulator platform. By jointly engineering waveguide trajectory modulation and propagation-constant mismatches introduced through non-uniform waveguide widths, we realize a half-wavelength-pitched dense waveguide array with a center-to-center spacing of 750 nm, far below conventional coupling-limited separations. The resulting array exhibits broadband crosstalk suppression below –20 dB over a 100-nm wavelength range (1500–1600 nm) with negligible excess loss. In parallel, we demonstrate AGF-enabled directional couplers with colorless and programmable splitting ratios, achieving wavelength-independent power division across the same bandwidth. Leveraging these near-dispersionless couplers, we construct a broadband Gaussian-weighted waveguide array and experimentally realize a two-dimensional optical phased array with a field of view of 120° × 14.5° and sidelobe levels below –17 dB. Our work establishes a scalable framework for broadband coupling control in ultra-dense photonic circuits, opening new opportunities for compact optical phased arrays, photonic delay lines, and high-capacity space-division multiplexing systems.