Japan Photonics Series
[Part 5. Light Approaches the Chip, but Products Are Made in the Package]
Japan’s manufacturing leverage in the last few centimeters of CPO and optical chiplet packaging
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AI servers are defined by GPUs and HBM. But the real bottlenecks often appear one layer lower.
Chips generate more data, memory moves closer, networks get faster — yet all that data must still travel between chips, packages, boards, and racks.
CPO (Co-Packaged Optics) is one direct answer to this problem. It pulls the optical-electrical conversion point closer to the ASIC or xPU package, shortening the expensive electrical path.
1. Surface Signal: Optical I/O is moving from the board edge into the package
Traditional data-center optics placed the optical module at the front panel. Electrical signals traveled across the board to the transceiver, then converted to light.
CPO changes that. It brings the optical engine right next to the ASIC or inside the package, reducing electrical travel distance, power loss, and heat.
Shinko Electric describes its optical chiplet/CPO development as combining its semiconductor packaging substrate and IC assembly expertise with optical assembly and optical wiring technologies.
2. Hidden Mechanism: CPO must solve three interfaces at once
CPO is not just about putting light closer to the chip. It requires simultaneous optimization of three interfaces:
1) Electrical-optical boundary: driver, TIA, modulator, photodiode, laser (or external laser).
2) Chip-package boundary: optical chiplet, ASIC, interposer, substrate, thermal path, alignment.
3) Package-external boundary: fiber attach, connector, external laser routing, serviceability.
The governing variable is not bandwidth alone.
It is whether the entire link budget, heat, alignment, yield, test, and field serviceability can be solved together inside the package.
3. Japan’s companies operate across four functional layersJapanese players in the CPO/packaging layer are best understood in four layers:
Layer 1 — Optical engine & CPO assembly
Shinko Electric and AIO Core. Shinko brings optical assembly to its existing packaging substrate strength. AIO Core provides the compact optical transceiver (IOCore).
Layer 2 — Ceramic, thermal, hermetic reliability
Kyocera, NGK, NTK. These companies supply ceramic packages, submounts, and bonded wafers (e.g., InP/SiC) that manage heat, moisture, and long-term stability in harsh package environments.
Layer 3 — Substrate, interposer, optical-material patterning
Ibiden, TOPPAN, DNP, Resonac. They develop FC-BGA, glass-core substrates, organic RDL interposers, and panel-level processes that form the physical foundation for heterogeneous integration.
Layer 4 — System demand anchor
Kioxia shows how optical I/O can actually change system architecture (optical SSD, disaggregation).
#CPO #OpticalChiplet #CoPackagedOptics #Packaging #JapanTech #SiliconPhotonics #AIInfrastructure #DataCenter