Waveguide superlattices with artificial gauge field toward colorless and low-crosstalk ultrahigh-density photonic integration

Dense waveguides are the basic building blocks for photonic integrated circuits（PICs）.Due to the rapidly increasing scale of PIC chips,high-density integration of waveguide arrays working with low crosstalk over broadband wavelength range is highly desired.However,the subwavelength regime of such structures has not been adequately explored in practice.We propose a waveguide superlattice design leveraging the artificial gauge field mechanism,corresponding to the quantum analog of field-induced n-"photon" resonances in semiconductor superlattices.This approach experimentally achieves-24 dB crosstalk suppression with an ultrabroad transmission bandwidth more than 500 nm for dual polarizations on the Si3N4 platform.The fabricated waveguide superlattices support high-speed signal transmission of 112 Gbit/s with high-fidelity signal-to-noise ratio profiles and bit error rates.This design,featuring a silica upper cladding,is compatible with standard metal back-end-of-the-line processes.Based on such a fundamental structure,which is readily transferable to other platforms,passive and active devices over versatile platforms can be realized with a significantly shrunk on-chip footprint,thus it holds great promise for significant reduction of the power consumption and cost in PICs.