LiDAR 2.0: Hierarchical Curvy Waveguide Detailed Routing for Large-Scale Photonic Integrated Circuits

2025-05-22

AI Summary

Manual routing in photonic integrated circuit (PIC) physical design is labor-intensive, while existing EDA tools struggle with curved waveguides, port alignment, and photonics-specific constraints. Method: This work proposes the first fully automated detailed routing framework supporting photonic design constraints. It introduces a hierarchical photonic routing architecture featuring redundancy bend elimination, jumper-space preservation, and routing-order optimization; employs curve-aware grid-based A* search, adaptive jumper insertion, congestion-aware net ordering, and joint insertion-loss optimization; and provides a YAML-based intermediate representation alongside open-source benchmarks (TeMPO/GWOR/Bennes). Contribution/Results: The framework achieves 100% DRV-free layouts across all benchmarks. In relaxed scenarios, it reduces insertion loss by 16% and accelerates routing by 7.69× versus prior methods; in compact scenarios, it outperforms LiDAR 1.0 by 9% lower insertion loss and 6.95× speedup.

Technology Category

• Planning, Routing, and Scheduling: Routing
• Search and Optimization: Mixed Discrete/Continuous Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Responsible Web: Human-perceived consequences of algorithmic deployment on the web
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

Driven by innovations in photonic computing and interconnects, photonic integrated circuit (PIC) designs advance and grow in complexity. Traditional manual physical design processes have become increasingly cumbersome. Available PIC layout tools are mostly schematic-driven, which has not alleviated the burden of manual waveguide planning and layout drawing. Previous research in PIC automated routing is largely adapted from electronic design, focusing on high-level planning and overlooking photonic-specific constraints such as curvy waveguides, bending, and port alignment. As a result, they fail to scale and cannot generate DRV-free layouts, highlighting the need for dedicated electronic-photonic design automation tools to streamline PIC physical design. In this work, we present LiDAR, the first automated PIC detailed router for large-scale designs. It features a grid-based, curvy-aware A* engine with adaptive crossing insertion, congestion-aware net ordering, and insertion-loss optimization. To enable routing in more compact and complex designs, we further extend our router to hierarchical routing as LiDAR 2.0. It introduces redundant-bend elimination, crossing space preservation, and routing order refinement for improved conflict resilience. We also develop and open-source a YAML-based PIC intermediate representation and diverse benchmarks, including TeMPO, GWOR, and Bennes, which feature hierarchical structures and high crossing densities. Evaluations across various benchmarks show that LiDAR 2.0 consistently produces DRV-free layouts, achieving up to 16% lower insertion loss and 7.69x speedup over prior methods on spacious cases, and 9% lower insertion loss with 6.95x speedup over LiDAR 1.0 on compact cases. Our codes are open-sourced at https://github.com/ScopeX-ASU/LiDAR.

Problem

• Automates photonic integrated circuit detailed routing
• Addresses photonic-specific constraints like curvy waveguides
• Scales for large, complex designs with DRV-free layouts

Innovation

• Grid-based curvy-aware A* routing engine
• Hierarchical routing with bend elimination
• YAML-based PIC intermediate representation