Lessengers unveiled an immersion-cooled, detachable 800G Near-Packaged Optics (NPO) module directly integrated with Alphawave Semi’s AlphaCHIP1600-IO chiplet at SC25 in St. Louis. The live demonstration fully submerges both the optical module and the chiplet in coolant, highlighting a path toward liquid-ready optical interconnects for AI data centers. The system also interoperates with Lessengers’ 800G optics operating in a commercially available 800G Ethernet switch.
The company’s NPO design is built on its patented Direct Optical Wiring (DOW) platform, a polymer-based air-cladded waveguide architecture that eliminates lenses, active alignment, and multi-channel assemblies. By creating a hermetically sealed optical environment, DOW protects components from immersion fluids, removing the added sealing and packaging steps typically needed to make optical modules liquid-cooling-ready. Lessengers said these attributes improve manufacturability, serviceability, and deployment flexibility across high-density AI clusters.
Lessengers is also showcasing 1.6T, 800G, and 400G optical modules, active optical cables, and future connectivity options for co-packaged and near-packaged optics. With 1.6T and 3.2T generation optics approaching commercial readiness, the company emphasized that immersion cooling will become essential as thermal loads surpass the limits of air cooling in dense rack designs.
• Immersion-cooled 800G NPO integrated with Alphawave Semi AlphaCHIP1600-IO
• DOW polymer waveguide design eliminates lenses, active alignment, and optical crosstalk
• Hermetically sealed structure protects optics from coolant without added sealing costs
• Demonstrated interoperability with a commercial 800G Ethernet switch
• Product portfolio includes 1.6T/800G/400G transceivers and AOCs
• Target applications include NPO, CPO, on-board optics, and AI data center interconnects
“Our partnership with Lessengers leverages their impressive DOW-based optical transceiver modules at the board interface and the direct integration of their NPO technology with our chiplet technology, enabling high-performance optical connectivity,” said Sue Hung Fung, Principal Product Line Manager at Alphawave Semi.
🌐 Analysis
Lessengers, founded in South Korea, has focused for more than a decade on replacing traditional lens-based optical coupling with its patented DOW (Direct Optical Wiring) technology. The platform uses polymer-based air-cladded waveguides to directly route light between silicon photonics engines and optical fiber without lenses, active alignment, or complex multi-element assemblies. This approach reduces manufacturing cost, improves ruggedness, and sharply lowers optical crosstalk. Lessengers has steadily expanded into high-volume 400G, 800G, and 1.6T transceiver production while positioning DOW as an enabling technology for CPO and NPO designs that must withstand immersion cooling. The company’s roadmap aligns closely with the hyperscaler pivot toward liquid-cooled AI fabrics, where chiplet-based IO, photonic integration, and serviceable near-packaged optics are converging. Partnerships with companies like Alphawave Semi underscore a strategy centered on chiplet-ready optical I/O for next-generation AI clusters.
