Copper scale-up is dead, making optics hyper bullish, especially Lumentum. Nvidia's Rubin NVLink Nyquist cut from 56 to 47 GHz signals failure: reflections matter, and bidirectional links make them worse. Feynman will have to use 16-wavelength DWDM ring-modulator CPO at roughly 50-64G NRZ. x.com  x.com 

More lasers per module and new 400G DSPs could keep the pluggable-optics runway open for years, supporting Lumentum, Coherent, Marvell, Applied Optoelectronics and Sivers even as co-packaged optics approaches. NVIDIA and Cisco co-designed a module with four times the bandwidth in the same slot; fewer modules per GPU look bearish, but the added optical content points the other way. x.com 

Wafer-tested VCSEL arrays could erode Lumentum's laser scarcity premium if scale-up links adopt wide, parallel designs. Lumentum's in-rack demo used arrays but does not replace every high-power laser; Credo and ams OSRAM seek approval for a parallel-link standard in 2027. Multiple suppliers would pressure pricing power and margins. Near-term earnings could still benefit from laser shortages, with Lumentum sold out through early 2029. x.com 

Marvell looks well positioned for scale-up compute domains, where interconnect is the wall that limits performance. Scale-up domains should be thought of differently from simply networking racks together, and Marvell's own commentary now focuses on exactly that opportunity. x.com  x.com 

A potential Lumentum acquisition could let Marvell pair custom AI chips with the optical infrastructure connecting them. Following Celestial AI, it could become one of the few companies offering both, moving toward an AI-focused version of Broadcom; financing a deal this large remains a major concern. x.com 

Lumentum and Coherent face a threat from microLED optics, which could replace laser optics with 20x less power and no temperature sensitivity by late 2027. The use case is short-reach, high-volume links under 30 meters. The copper versus optics debate is a distraction, since every AI cluster needs both and Credo now does both while Applied Optoelectronics handles long-haul; the bigger question is what microLED does to laser makers. x.com  x.com 

Optical networking's broader rollout will be slow because scale-up and scale-out require orders of magnitude more connections than today's limited optical distance links. Supply-chain discussions echo that slow pace. NPO/CPO starts in switches and reaches XPUs and GPUs much later, with new challenges. Optical backplanes will be necessary as racks move to optical, though copper will remain in many implementations. x.com  x.com  x.com  x.com 

Marvell risks paying a peak-scarcity price for Lumentum if optical supply catches up by 2028-30. The proposed ~$99B deal values Lumentum at roughly 20x guided annualized revenue and 58x estimated after-tax operating income, while Lumentum, Coherent and Chinese suppliers are adding laser capacity. The DSP-and-laser combination has strategic logic, but durable scarcity economics and Nvidia's response remain uncertain. x.com 

Applied Optoelectronics and Lumentum face lower optical transceiver demand as two new network designs cut optical links per GPU. Amazon says its Resilient Network Graphs use 69% fewer routers and became the default for most new AWS data centers by April 2026. OpenAI says its Multipath Reliable Connection protocol links over 100,000 GPUs with two switch tiers instead of three or four. B. Riley reportedly sees transceiver counts falling 40-50% and cut Applied Optoelectronics to Neutral. x.com 

Tighter Lumentum laser allocations would strengthen Coherent's pricing power if Marvell's rumored acquisition leads it to prioritize Nvidia and its own modules. Other buyers would face tighter supply, and hyperscalers would push harder to second-source lasers from Coherent. x.com