[CPO Deep Dive 5/6] The CPO Ecosystem Is Being Reshuffled: Foundries and OSATs Move From Supporting Cast to Lead

CPO doesn't just change the technology; it changes how power is distributed across the entire value chain. As the optical path moves closer to logic and packaging grows more complex, value shifts from "module assembly" to "advanced packaging." The biggest winners are not the veterans who spent two decades on optical modules, but the foundries and OSATs that hold both silicon photonics manufacturing and advanced packaging capabilities. This piece breaks down the CPO supply chain from upstream materials all the way to module makers, explains why Taiwan's ecosystem is restructuring around foundries and OSATs, and why "standardization" is what really decides this reshuffle.

1. The Reshuffle in One Sentence: Value Is Flowing Toward Packaging

Conclusion first; the rest of this piece makes the case: CPO redistributes value across the optical communications chain, and the biggest winner is whoever can "stack" optics and electronics together.

In the pluggable era, value was spread across lasers, SiPh, and module assembly, and module makers captured a sizable share on their "assembly know-how." But CPO stacks the PIC and EIC directly (a packaging approach we broke down in the "packaging evolution" installment of this series), and that stacking pushes value hard toward advanced packaging. Who can do it? Not traditional optical module makers, but foundries and OSATs with both silicon photonics manufacturing and advanced packaging capabilities.

In other words: the more an optical engine looks like a chip, the more this business looks like semiconductors rather than optical assembly. Whoever controls the semiconductor volume-manufacturing machine moves toward the core of the value chain.

2. Why Now: As Optics Move Closer to Logic, Packaging Absorbs the Value

This reshuffle did not come out of nowhere; it has a clear trigger: the optical path is moving step by step toward compute logic.

Step one: the optical engine moves from the switch front panel to sit beside the ASIC (with the EIC integrated first). Step two, the longer-term vision: the optical path moves right up against the GPU and HBM, making light the medium for chip-to-chip communication. Each step closer raises packaging complexity a notch, and lets this stage capture more of the value.

This explains an industry phenomenon: why the leading foundry suddenly cares so much about CPO. It is pushing its own universal integration platform and positioning itself as a "just place the order" turnkey supplier; if it succeeds, it captures the two richest slices of value at once, silicon photonics manufacturing and advanced packaging. This isn't technical curiosity; it's positioning in the value chain.

3. Taking the CPO Supply Chain Apart: From a Wafer to an AI Server

To understand the reshuffle, you first need a map of the whole chain. From top to bottom, the CPO supply chain has roughly five stages:

Stage one: upstream materials. This is the bottom layer, the least discussed yet the most critical foundation: silicon wafers, silicon-on-insulator (SOI) wafers, indium phosphide (InP), and optical-grade glass. Supply of these materials is highly concentrated among a few specialists; for SOI wafers, InP substrates, and optical glass alike, only a handful of companies can reliably supply high-quality, large-diameter material. This creates an often underestimated risk: CPO's volume bottleneck may not be the chip at the top, but a specialty wafer at the very bottom. Scale-out applications tend to use cost-friendly substrates to drive volume, while scale-up needs high-performance materials to meet AI bandwidth demands. Whoever controls the capacity and yield of these upstream materials holds a valve that nobody is watching, yet one that can choke the entire chain.

Read the full analysis on vocus (in Chinese): https://vocus.cc/article/6a60285efd897800018c7e05