Lightmatter joins Open CPX MSA and unveils BiDi optical module for AI infrastructure

Lightmatter has joined the Open CPX MSA and introduced Passage L20 CPX, a bidirectional-optics module for AI infrastructure built on the company’s Passage L20 NPO optical engine.

The module uses a single fibre path for transmit and receive traffic at different wavelengths. Lightmatter describes the design as providing 12.8 Tbps of aggregate bandwidth: 6.4 Tbps in each direction. It has 32 optical channels per direction, uses PAM4 signalling at 212.5 Gbps, and supports transmission over more than 500 metres of single-mode fibre. The specified O-band wavelengths are 1331 nm and 1311 nm.

The company plans to begin shipping Passage L20 CPX evaluation kits in the first quarter of 2027. This is a planned evaluation-kit timeline, not confirmation of commercial deployment or volume shipments.

Lightmatter’s analysis for a 512-GPU scale-up pod indicates that bidirectional optics could reduce the fibre count from about 130,000 to 65,000, saving more than 200 miles of fibre and roughly 16,000 connectors. The company also estimates approximately 15% savings in total scale-up interconnect-network cost for that configuration.

For large AI clusters, fibre routing, connector count and the time required to bring a pod online can constrain scaling alongside compute resources. A reduction in fibre and connection points could lower installation complexity and potential failure points. However, the cited savings are specific to Lightmatter’s 512-GPU pod analysis and may not translate directly to other AI-cluster architectures.

Open CPX MSA defines a standardised form factor for CPO and NPO modules delivering high-speed, low-latency I/O close to ASICs, switches or GPUs. Lightmatter’s participation could help create conditions for broader multi-vendor deployment of NPO/CPO components, but commercial impact remains unproven until evaluation and production deployments validate the claimed performance and infrastructure savings.