- Lightmatter officially introduced Passage L20 CPX on September 17 and joined the Open CPX MSA, describing the product as the first bidirectional Open CPX optical engine for AI infrastructure. - Passage L20 CPX uses 1311 nm and 1331 nm wavelengths to carry transmit and receive traffic over the same single-mode fiber, cutting fiber and connector requirements by roughly 50% versus conventional UniDi architectures. - The module is designed for 6.4 Tbps Tx plus 6.4 Tbps Rx, or 12.8 Tbps aggregate bandwidth, using 32 optical lanes per direction at a 212.5 Gbps PAM4 line rate with more than 500 meters of SMF reach. - In Lightmatter's 512-GPU scale-up pod model, the architecture reduces fiber count from roughly 131,072 to 65,536 while eliminating approximately 16,000 connectors and more than 200 miles of fiber. - Lightmatter estimates that BiDi could reduce total scale-up interconnect network spending by roughly 15%, although this figure comes from internal modeling and will vary by topology and deployment configuration. - Importantly, this is not yet a volume-production product. Passage L20 CPX evaluation kits are expected to ship to customers in Q1 2027, and the disclosed specifications remain preliminary. - The announcement follows Lightmatter's June entry into NVIDIA's NVLink Fusion ecosystem and its August launch of an OCP CPO architecture effort targeting AI systems scaling from 72 to more than 1,024 nodes.