How Optical Modules Power the AI Factory: Spine-Leaf Architecture Upgrades from 100G to 400G and 800G

The concept of the "AI factory" has rapidly emerged as a defining model for next-generation data centers. Unlike traditional enterprise or cloud data centers, AI factories are purpose-built to support large-scale AI training and inference workloads, such as large language models (LLMs), multimodal foundation models, and real-time generative AI services. These workloads generate unprecedented east–west traffic, placing extreme demands on data center networks in terms of bandwidth, latency, and scalability. At the heart of this transformation lies the evolution of optical modules. As GPU clusters scale from hundreds to tens of thousands of accelerators, legacy 100G and 200G networks are no longer sufficient. The industry-wide transition toward 400G and 800G optical modules—especially within spine-leaf architectures—has become a foundational requirement for building efficient and future-ready AI factories. This article examines why spine-leaf networks must evolve, how 400G and 800G optica