Test economics will determine whether CPO can move from the lab to high-volume production

Overview

As GPU clusters, distributed inference and high-speed switching networks expand, 224 Gbps infrastructure is gradually showing limitations, while demand for 448 Gbps per channel and higher bandwidth such as 800G and 1.6T is pushing optical interconnects closer to ASICs, xPUs and advanced packaging. The report argues that the technology direction for silicon photonics and CPO is already relatively clear, but the key to truly entering the AI supply chain is not merely whether photonic chips can be manufactured, but whether stable, automated, standardized and economical electro-optical hybrid testing can be completed using semiconductor mass-production methods.

Core views

First, competition in AI infrastructure is shifting from single-chip performance to system-level interconnects, and CPO represents a reconstruction of AI system architecture rather than a simple upgrade of traditional optical modules. Second, after optics enter the package, the failure of a single optical engine may drag down a high-value package containing logic chips, HBM, interposers and substrates, so testing must be moved forward to form “known good optical engines” before integration with SoCs. Third, optical probing, fiber connector handling and automated instruments still lack mature standards, and measurement results are also affected by alignment, polarization, temperature drift, connection status and optical path loss. Fourth, CPO testing must be integrated into early product design and form a collaborative ecosystem covering ATE, probers, handlers, interface hardware, optical instruments, thermal control, calibration models and software APIs. Fifth, future supply chain barriers will be reflected in the ability to convert unstable optical coupling into repeatable, calibratable and mass-producible processes.

Analysis framework

The report starts from the interconnect bottleneck in AI compute systems and analyzes the industrial logic of optics migrating from outside the rack into the package. It then breaks down the mass-production process by insertion points such as PIC wafers, EIC-PIC wafers, post-dicing optical engines, advanced ASIC/CPO packaging and system-level testing, and evaluates the yield, throughput, standardization and cost conditions required for CPO commercialization by incorporating Advantest’s proposed test ecosystem direction, existing equipment solutions and supply chain division of labor.

Methodology notes

• Manufacturing and yield managementShift-left testing

  Add earlier and more intensive test insertion points before high-value packaging and system integration.

  Through wafer-level and optical-engine-level screening, optical path loss, modulation abnormalities, dark current, coupling and loopback failures can be detected early, reducing the cost of complete package scrapping caused by defect amplification downstream.

• Advanced packaging quality controlKnown good optical engine

  Extend the traditional “known good die” principle to optical engines integrating optical functions.

  Confirm electrical and optical performance before the optical engine is packaged together with SoCs, HBM and other expensive components, in order to improve final package yield and clarify supply chain quality responsibility.

• Industrialization assessmentYield–time–cost framework

  Measure CPO scalable deployment capability through yield, test time and test cost.

  Technical feasibility does not equal commercial feasibility; only when test speed, repeatability, automation level and unit test cost meet mass-production requirements can CPO form a scalable supply chain.

• Industry ecosystem analysisComplete test cell framework

  Treat equipment, interfaces, instruments, software, calibration and design for testability as an interdependent production system.

  Any link among ATE, probers, handlers, probe cards, DUT boards, optical instruments, fiber alignment units, connectors, thermal control and software APIs may become a throughput or consistency bottleneck.

Asset mapping & comparison

Structured mapping from thesis to named assets (strengths, weaknesses, peers, risks).

• Advantest

  An important driver of the CPO and silicon photonics automated testing ecosystem

  Strengths

  It has ATE and semiconductor mass-production testing experience, and promotes the integration of standard equipment with high-density optical instruments, automated handling and control software.

  Weaknesses

  A complete CPO test cell depends on external partners such as probers, probe cards, connectors, instruments and customer designs, making it difficult for a single vendor to complete independently.

  Comparison

  Compared with traditional laboratory optical testing solutions, it places greater emphasis on high throughput, automation, scalability and compatibility with existing semiconductor testing infrastructure.

  Risks

  Slow formation of industry standards, divergence in customer test architectures, complex optical interfaces and CPO mass-production progress falling short of expectations.

• TSMC

  A key participant in the advanced wafer manufacturing and packaging ecosystem

  Strengths

  It has advanced process technologies and advanced packaging capabilities such as CoWoS, and occupies a core position in the AI and HPC supply chain.

  Weaknesses

  CPO mass production still depends on collaboration with external optical testing, connector, alignment and instrument ecosystems.

  Comparison

  Its manufacturing and packaging capabilities provide a foundation for CPO integration, but the report emphasizes that the industry bottleneck is further extending to electro-optical hybrid testing.

  Risks

  Invisible optical engine yield or immature test standards may amplify the scrapping cost of high-value packages.

• ficonTEC

  Supplier of double-sided electro-optical wafer-level test equipment

  Strengths

  Its solution supports simultaneous electrical and optical probing on both sides of the wafer, and is compatible with industry-standard ATE platforms and automated wafer loading processes.

  Weaknesses

  Precision alignment, customized fixtures and fiber array probes still bring equipment complexity and mass-production validation requirements.

  Comparison

  Compared with single-sided or laboratory-style testing, the double-sided architecture is more suitable for vertically integrated photonic and electronic die stacking.

  Risks

  There is uncertainty in equipment cost, customer adoption cycles, test throughput and compatibility with different package structures.

• TE Connectivity

  Supplier related to high-speed interconnects and 448G connection solutions

  Strengths

  It has a product foundation in connectors and high-speed interconnects and may benefit from AI data center bandwidth upgrades.

  Weaknesses

  The report does not provide data on the scale, market share or profit contribution of its CPO testing business.

  Comparison

  Its positioning leans more toward interconnect interfaces and connection solutions rather than complete ATE or wafer-level electro-optical testing platforms.

  Risks

  Evolution of high-speed standards, customer architecture choices and CPO substitution for traditional connection forms may affect demand structure.

Key data

• Next-generation single-channel rate448 GbpsCompared with current 224 Gbps infrastructure, it not only increases speed but also drives changes in data center density, power consumption and interconnect architecture.
• AI data center high-speed links800G, 1.6T and aboveHigher bandwidth demand weakens the applicability of traditional copper interconnects and purely pluggable optical modules in terms of power consumption, signal integrity and package area.
• Major CPO testing gaps3 itemsThey include the lack of unified standards for optical probing, fiber connector handling relying on manual labor, and highly customized rack-mounted configurations for optical instruments.
• 12-inch PIC wafer test timeUp to approximately 12 hoursThis data refers only to the PIC portion, showing that wafer-level test throughput may become an important constraint on silicon photonics mass production.
• Key commercial variables for testingYield, test time, test costTogether, the three determine whether CPO can move from technical validation to large-scale deployment in AI systems.
• Scale of open supply chain ecosystemNearly 60 membersThe report cites open ecosystem information from the Advanced Photonics Coalition as of June 2026, reflecting that CPO requires cross-segment collaboration.

Impact & implications

Testing will rise from a back-end auxiliary step to become part of CPO product definition, yield models and cost structure. Potential beneficiaries may include suppliers with capabilities in high-density ATE, electro-optical wafer probing, double-sided testing, precision fiber alignment, automated handling, calibration software and standardized instrument interfaces. Wafer foundries, advanced packaging providers, optical engine vendors, switch chip suppliers and cloud service providers also need to jointly determine test standards and yield responsibilities. For the Taiwan, China supply chain, existing strengths in wafer manufacturing, advanced packaging and IC testing provide a foundation, but optical probing, FAU alignment, connector automation and calibration standards still need to be strengthened.

Risks

• Optical probing, connector handling and instrument control standards may remain ununified for a long time, leading to excessive customer customization costs.
• Active multi-axis alignment may take too long, limiting wafer-level and package-level test throughput.
• Alignment errors, polarization, temperature drift, optical path loss and calibration errors may reduce test repeatability and cross-equipment correlation.
• If CPO product designs lack testability structures such as optical loopbacks, on-chip monitoring and thermal sensors, back-end fault localization will become more difficult.
• A defect in a single optical engine may cause the loss of high-value ASICs, HBM and the entire advanced package.
• If CPO testing costs cannot fall to a reasonable level, it may lack commercial competitiveness even if technically feasible.
• Unclear supply chain quality responsibility and yield definitions may delay customer qualification and scaled deployment.

What to watch

• Mass-production progress of 448 Gbps per channel, 800G and 1.6T interconnect standards and the pace of adoption by AI data centers.
• Whether known good optical engines become a common acceptance standard for wafer foundries, packaging houses and system customers.
• Progress in interface standardization among optical probes, FAUs, connectors, handlers and ATE.
• Improvement speed in PIC wafer-level test time, parallel test capability and unit test cost.
• Maturity of optical instrument control libraries, automatic calibration and cross-test-cell correlation solutions.
• Whether CPO products incorporate optical loopbacks, monitor photodiodes, thermal sensing and automatic calibration structures at the early design stage.
• Collaboration and customer validation among Advantest, prober vendors, probe card vendors, optical instrument suppliers and packaging companies.
• Capability building in the Taiwan, China supply chain in electro-optical integrated testing, fiber alignment and connector automation.