Lightmatter Introduces Passage L20 CPX Bidirectional Module After Joining Open CPX MSA

Lightmatter said it joined the Open CPX Multi-Source Agreement (MSA) and introduced the Passage L20 CPX bidirectional CPX optical module. The company positioned the change as a way to reduce optical cabling needs in AI scale-up networks.

The release said fiber cabling can limit how fast AI clusters are built, because conventional links use separate fibers for transmit and receive. Lightmatter described bidirectional (BiDi) optics as combining transmit and receive on a single fiber by using separate wavelengths for each direction.

Lightmatter said the Passage L20 CPX module follows a co-packaged optics approach, with the optical component placed near the host ASIC, switch, or GPU and mounted to the PCB or substrate. It said the module supports O-band wavelengths at 1331 nm and 1311 nm, reaches beyond 500 meters over single-mode fiber, follows the IEEE 802.3dj DR link architecture, and uses OIF-CMIS management protocols.

The companies described the Open CPX MSA as defining a standardized CPO/NPO module form factor for high-bandwidth, low-latency I/O. Lightmatter said the Passage L20 CPX is built on the Passage L-Series optical engine platform, delivering 12.8 Tbps total bandwidth (6.4 Tbps transmit and 6.4 Tbps receive) and 32 optical lanes per direction at a 212.5 Gbps PAM4 line rate. Nick Harris, Ph.D., Founder and CEO of Lightmatter, said, “AI infrastructure is scaling faster than copper can follow, and co-packaged optics is the answer. CPX is the on-ramp. It gets the optics, the fiber, and the supply chain into production now, so that when CPO arrives, the hard parts are already proven. That's why we joined the Open CPX MSA,” said Nick Harris, Ph.D., Founder and CEO of Lightmatter. “Passage L20 CPX is bidirectional and enables transmit and receive over a single fiber, which halves fiber requirements. At cluster scale that means faster bring-up, fewer failures, and less time chasing broken links.” Sameh Boujelbene, Vice President at Dell'Oro Group, said, “As AI clusters scale up, the constraints are shifting from compute to the physical infrastructure around it, including power, cabling, and the time it takes to bring a pod online,” said Sameh Boujelbene, Vice President at Dell'Oro Group. “Standardization efforts like the Open CPX MSA are critical to commercializing optics close to the package across a broad multi-vendor ecosystem. A bidirectional architecture that halves fiber count without giving up bandwidth addresses a cost and complexity problem that operators feel immediately.” Lightmatter said Passage L20 CPX module evaluation kits were anticipated to ship to customers in the first quarter of 2027.

Press release, provided by Cision on behalf of Lightmatter®. Read the original.