Lumentum makes optical and photonic components, modules, and systems used in cloud and AI data center infrastructure and telecom networks. The company's most important product is the EML (electro-absorption modulated laser) chip — a laser transmitter component that converts electrical signals to optical signals inside data center networking gear. Lumentum sells these chips to optical transceiver manufacturers, who build them into products for hyperscale cloud and AI operators. Lumentum also makes complete optical transceiver modules through its Cloud Light business, and sells a broad telecom portfolio including tunable lasers, coherent components, ROADMs (devices that route optical signals in networks), and amplifiers. These products make up the Cloud & Networking segment, roughly 88% of revenue. The remaining ~12% comes from Industrial Tech: VCSEL laser arrays for smartphone 3D sensing (face ID) and ultrafast/fiber lasers for precision manufacturing in semiconductors, EVs, and solar cells. Lumentum's EML chips are manufactured at its indium phosphide wafer fab in Japan, where supply has consistently lagged demand, giving Lumentum pricing leverage. Transceiver modules are assembled primarily in Thailand. The components business carries above-average margins; modules carry lower margins, though Lumentum is working to improve module margins by incorporating its own EML chips. Lumentum sells to a concentrated customer base — two customers each represented roughly 15-16% of FY25 revenue. Key growth bets include 200G EML chips for next-gen transceivers, optical circuit switches that replace electronic switches in data centers, and co-packaged optics, where Lumentum supplies what it describes as a sole-sourced laser for at least one major AI customer.