TriHOT: Triangular and Hexagonal Norm Based Timing-Driven Optical Routing with Wavelength Division Multiplexing

As semiconductor technology continues scaling, interconnect delay becomes a major bottleneck for circuit performance. On-chip optical interconnect with wavelength division multiplexing (WDM) is a promising alternative due to its high speed, broad bandwidth, and energy efficiency. Previous work estimates the timing of an optical interconnect in terms of \(L_1\) or \(L_2\) norm and simplifies its timing gain based on a distance threshold. This estimation and simplification cannot capture the essence of optical routing and the impact of WDM, and may cause timing degradation. In this work, we propose a novel timing model based on a unified triangular and hexagonal norm and establish a wirelength lower bound to measure the routing quality. Moreover, we reduce the WDM-aware optical routing to the Maximum Weighted Independent Set (MWIS) problem and approach it by weighted interval scheduling in linear time-space. Experimental results show that our method outperforms the state-of-the-art in terms of timing, wirelength, and transmission loss with comparable runtime.