Optical Module Technology Breakthrough: AI-Driven High-Speed Interconnect Solutions Shine at Hot Chips

Optical Module Technology Breakthrough: AI-Driven High-Speed Interconnect Solutions Shine at Hot Chips

September 6, 2025

Driven by the rapid evolution of artificial intelligence, the optical module and high-speed interconnect industry is experiencing unprecedented innovation. Important global events in the semiconductor and optoelectronics field—Hot Interconnects 2025 (HotI) and Hot Chips—were recently held online and in person, with leading companies disclosing latest technological advances, especially around co-packaged optics (CPO), silicon photonics, and optoelectronic integration.

NVIDIA Introduces Spectrum-XGS, Optimizing Inter-Data Center Connectivity
Although NVIDIA did not reveal specific technical details of its CPO switches during the Optical session, it officially launched Spectrum-XGS—a new Ethernet solution designed to extend its Spectrum-X architecture to support low-latency connections across data center clusters. NVIDIA refers to this as “scale-across networking,” emphasizing optimization for propagation delay and load balancing over longer links, significantly reducing jitter and improving stability for AI workloads. The company also highlighted that traditional deep-buffer switching architectures may introduce performance jitter in AI scenarios, making the new solution more advantageous.

Startups Active in Optical I/O Integration with Forward-Looking Proposals
Three optical technology startups also presented cutting-edge solutions:

Ayar Labs launched its third-generation TeraPHY UCIe optical retimer chiplet, supporting 8Tbps bandwidth and adopting the UCIe die-to-die standard for better integration with XPUs or ASICs, enhancing the versatility and performance of CPO solutions.

Lightmatter’s Passage M1000 uses a breakthrough interconnect architecture, employing 3D stacking and interposer technology to achieve high-density connections between optical chips and ASICs, moving beyond traditional I/O limitations.

Celestial AI advocated for the use of electro-absorption modulators (EAMs) in CPO and introduced what it claims is the first “Photonic Fabric Module” with on-die optical I/O, using 3D integration to stack an EIC on top of a PIC.

Divergent Technical Paths: Mass Production and Ecosystem Collaboration Are Key
From the conference, it is clear that Ayar Labs—with its relatively mature integration approach—is closer to mass production. Meanwhile, Lightmatter and Celestial AI, despite demonstrating higher power efficiency and integration density, require customers to co-design ASICs tailored to their platforms, implying higher technical risk and ecosystem dependency. Although no major XPU manufacturer has yet announced adoption of such highly customized CPO solutions, the technical potential has drawn widespread industry attention.

Source: Lightcounting
(This article is adapted and edited based on the September 2025 report “Hot Conferences Feature Cool Optics” by Lightcounting. Content has been simplified and reorganized for clarity. Full text is available to subscribers at: https://www.lightcounting.com/login)