In a traditional data center architecture, optical fiber connects switches to each other, but that fiber only goes to the faceplate. A pluggable transceiver on the front of the box converts the optical signal to an electrical one, and data travels across roughly a foot of copper traces before reaching the chip. That distance may not sound like much, but at the speeds modern AI workloads demand, it becomes a real problem.
What's the issue with the current setup? Power consumption climbs sharply because compensating for a noisy electrical channel over that distance takes heavy digital signal processing (DSP) work. Signal integrity degrades, crosstalk increases, and you eventually run out of usable PCB area for high-speed traces.
CPO addresses most of those issues at once by treating the signal path as one optimized system instead of a chain of independent parts. The transceiver function still exists. Light still has to be converted to an electrical signal. But with CPO and NPO, the result is better power efficiency, lower latency, higher density, and greater reliability. A unified system design brings major benefits, but it is also a key challenge we’ve worked to simplify.
The real complexity is inside the box
A single CPO assembly can route well over 1,000 fibers in tight internal volumes, each landing on a photonic integrated circuit (PIC) within sub-micron alignment tolerances. Getting that right at hyperscale volumes means balancing four requirements that affect each other:
- Performance, including minimized insertion loss
- Density, or the number of fibers that can fit within a limited space
- Reliability under operational stress
- Ease of assembly at manufacturing scale
These four aspects pull against each other in practice. Every choice made to hit one target affects the others. The trade-offs are only resolved when the front plate connector, specialty optical fiber, and fiber array units are designed and managed together against the same target.
Why integration improves reliability
Because this is a highly integrated system, parts inside the box are generally not field-replaceable or serviceable. That may sound like a drawback until you look at the reliability data. Publicly reported testing of CPO switch platforms has demonstrated the potential for highly reliable operation over extended link-hour testing. One such test demonstrated one million link hours without a single link flap. Link flaps are brief connectivity disruptions and one of the most closely watched reliability metrics in high-performance data center networks. That result is achievable when the entire optical path is treated as one engineered link, not a chain of independently sourced components.
Reliability has long been the subject of research at Corning. A white paper produced by Corning and Broadcom explores the design and handling practices developed over decades to ensure high reliability when using optical fibers, with a specific focus on emerging CPO designs.
