Broadband nonvolatile optical switches enabled by artificial gauge field

Nonvolatile optical switches based on phase-change materials (PCMs) are essential building blocks for reconfigurable photonic integrated circuits with reduced power consumption. However, the operating bandwidth of existing PCM optical switches is typically limited by modal dispersion. Here, we propose a broadband nonvolatile optical switch based on artificial-gauge-field-driven broadband 3 dB power splitters in a Mach-Zehnder interferometer (MZI) configuration. Although broadband power splitting is accompanied by phase dispersion across the 3 dB splitting bandwidth, this issue is addressed by introducing local dispersion control through asymmetric MZI arms. In addition, broadband differential phase tuning between the two arms is achieved by integrating a low-loss PCM into shallow-slot waveguides. The proposed device achieves an operating bandwidth of 170 nm with a switching extinction ratio exceeding 15 dB and an insertion loss below 0.78 dB. Our design provides a promising route toward compact, energy-efficient, and broadband optical routing for large-scale reconfigurable photonic integrated circuits.