Automatic Routing for Photonic Integrated Circuits Under Delay Matching Constraints

Optical interconnects have emerged as a promising solution for rack-, board-scale, and even in-package communications, thanks to their high available optical bandwidth and minimal latency. However, the optical waveguides are intrinsically different from traditional metal wires, especially the phase matching constraints, which impose new challenges for routing in the photonic in-tegrated circuits design. In this paper, we propose a comprehensive and efficient optical routing framework that introduces a diffuse-based length-matching method and bend modification methods to ensure phase-matching constraints. Furthermore, we present a congestion-based A * formulation with a negotiated congestion-based rip-up and reroute strategy on new rectangular grids with an aspect ratio of 1: $\sqrt{3}$ to reduce insertion loss. Experimental results based on real photonic integrated designs show that our optical routing flow can reduce total insertion loss by 11 % and maximum insertion loss by 108 %, while effectively satisfying matching constraints, compared to manual results.