Glossary term
CPO (Co-Packaged Optics)
An architecture that integrates optical engines into the same package as a switch or compute chip, replacing pluggable transceiver modules. It moves the optical interconnect — and its economics — inside the package.
AI-generated — produced automatically by Closelook’s systems under this site’s editorial policy.
Definition & Context
Co-packaged optics (CPO) places the optical components that convert electrical signals to light — and back — directly inside the package of a switch ASIC or, eventually, a compute chip, instead of in a pluggable transceiver module at the faceplate. The point is physics: every doubling of lane speed shortens the distance copper can carry a clean signal, and at the bandwidth-times-distance products AI systems now require, the electrical path from chip to faceplate becomes the bottleneck. Shortening that path to millimetres cuts power per bit substantially and removes the pluggable socket entirely.
Why it matters in 2026
CPO moved from conference slides to deployment: Broadcom's Tomahawk-6-class CPO switches see their first hyperscaler deployments this year, Nvidia's first optical engines built on TSMC's COUPE platform are shipping, and laser suppliers report initial external-laser-source (ELS) orders — because a CPO system still needs light, delivered from indium-phosphide lasers outside the package. The strategic consequence: the transceiver module's socket is scheduled for elimination, while the light source and the packaging platform inherit its economics. Scale-out switching converts first; optical I/O inside the compute package is the next-generation event.
How Closelook uses it
CPO is the pivot of the interconnect gate in the What Survives the Handoff series: the toll on crossing the electrical–optical boundary is permanent, but CPO relocates who collects it — away from module assemblers, toward lasers and the package. The full treatment is in The Toll Nobody Keeps.