An 850nm VCSEL that passed a 20-year, 100G production spec failed after 1,600 hours in scale-up rack thermal conditions, while a 1060nm device under identical conditions ran 5,000 hours unscathed. At ECOC 2026, Lumentum used one chart to show the VCSEL bottleneck was never speed—it is heat.

Broadcom's CPO session skipped the theory and laid out field failure data from three product generations, because what holds CPO back was never power, but how to fix it when it breaks. With reliability now the selling point, the OCI spec and a 2027 fourth generation are opening three orders for Taiwan's supply chain.

It takes fourteen kinds of engineers to build an optical module, and design is only half of them. The free section walks through what each of the fourteen functions does; the four hand-off interfaces that really set the pace of yield ramp are broken down in the paid section.