Abstract
<title>Abstract</title> <p>The Y-junction is a fundamental passive device in photonic integrated circuits, widely used for on-chip optical power splitting, combining, and routing. Its performance directly affects the insertion loss, operating bandwidth, and integration density of optical integrated systems. To address the sensitivity of conventional inverse-designed Y-junctions to fabrication errors and the resulting performance degradation after practical fabrication, this work introduces a fabrication-oriented robustness optimization method that accounts for process variations during the design stage, thereby improving fabrication tolerance and practical feasibility. The proposed device supports multiple asymmetric splitting ratios, enabling flexible optical power distribution for different application requirements. The results show that the robust inverse-designed Y-junction achieves low insertion loss, broadband operation, and good manufacturability while maintaining a compact footprint, providing a useful reference for the design of high-performance and scalable manufacturable integrated photonic devices with potential applications in optical computing, optical interconnects, and related integrated photonic systems.</p>