Test vendors are reworking production test cells for near-packaged optics and co-packaged optics as these architectures move closer to mainstream data center deployment. The challenge is no longer limited to optical measurement itself. High-volume manufacturing now demands automation, software support, data analysis, and repeatable optical interfacing at wafer, optical-engine, die, package, module, and system level.
One of the biggest shifts is the need to support different connection schemes at scale. Depending on the insertion, the device under test may require fiber alignment, connector alignment, or receptacle alignment. That is much harder to industrialize than the lab-style rack-and-stack setups used in characterization. Alignment tolerances are extremely tight, and even small pitch or x-y mismatches can introduce measurable channel variation. An optical probe card would help, but it is difficult to implement because it must combine non-contact mechanics with calibration that is reliable and traceable.
The lack of optical design-for-testability adds another layer of complexity. Instead of testing a system with built-in access points, many flows still require individual checks of waveguides, rings, modulators, and related elements. PRBSpseudo-random binary sequencesDeterministic bit patterns that resemble random data and test digital communication links.-based approaches are being used, but they do not remove the need for slow, component-by-component testing. In addition, the industry is still maturing around standards, connection technologies, and laser source choices, which keeps the test flow fluid.
Several test insertions are already emerging: PIC1. Physical interfaces and carriers2. Photonic Integrated CircuitA circuit that integrates optical functions on a photonic chip. testing, wafer-level optical-engine testing, die-level optical-engine testing, module test, and system-level test. A wafer-level burn-in step is also used for optical stability and laser infant mortality screening. For some customers, the full mission-mode test of a CPOco-packaged opticsOptical devices and CPUs are integrated into a single package module may be done on ATEautomatic test equipmentAutomated system for measuring and functionally testing electronic devices., on SLTsystem level testA test mode that exercises a device in a more realistic system environment with software and workloads., or on both. The test load is substantial, with optical connections ranging from 4 to 32 connectors and power requirements reaching 1 to 8 kW for the center die and 10 to 30 W per optical engine.
Connector choice remains unsettled. Customers are weighing repeatability, reliability, optical performance, and compatibility with FAUfiber array unitoptical connection between a photonic chip and fibers, while second sourcing could introduce additional mismatch if connector types diverge. Large-scale packages add another risk: warpage can shift a connector far enough to shear it off. Automated cleaning is also becoming essential because dust is a major failure mode in optical testing. Two-row FAUfiber array unitoptical connection between a photonic chip and fibers and even FAUfiber array unitoptical connection between a photonic chip and fibers with hundreds of fibers are already entering the discussion, underscoring how quickly the test target is still moving.