Reliability Becomes the New Currency: How CPO Is Rewriting Laser Performance

A Formula 1 car doesn't win on horsepower alone. The fastest engines in the sport lose to slower ones every season because reliability—not peak performance—is what carries a car across the finish line. 

The same logic is beginning to reshape how hyperscalers think about AI networking infrastructure. 

CPO's Value Proposition: From Power Savings to Reliability 

Co-packaged optics (CPO) first emerged as a power-efficiency story. By moving optical engines closer to the switch ASIC and eliminating long, high-loss electrical traces, CPO can make optical I/O approximately 3.5x more power efficient than traditional pluggable optics. For hyperscalers deploying AI clusters with hundreds of thousands of accelerators, those savings translate into meaningful reductions in power consumption and operating costs. 

But recent industry developments suggest that power efficiency may not be the most important benefit of CPO. 

In late 2025, Broadcom reported one million cumulative 400G-equivalent port device hours of flap-free CPO operation at Meta, along with significant power savings and improved link reliability compared to pluggable optics¹. Shortly thereafter, NVIDIA reported that CPO-based systems delivered a 10x improvement in AI cluster resiliency, translating into substantially higher GPU utilization². 

The implication is difficult to ignore. In large AI clusters, a single optical failure can affect thousands of GPUs and disrupt hours of training time. While power efficiency delivers recurring operational savings, reliability failures can have outsized operational consequences. 

This shift in thinking is arriving just as the AI optics market enters a period of extraordinary growth. Industry forecasts project AI-related optical networking to exceed $50 billion by 2031, with AI scale-up architectures representing one of the fastest-growing segments. As CPO adoption accelerates, millions of external laser sources are expected to be deployed throughout AI infrastructure, making laser reliability a foundational requirement rather than simply a component specification. 

Why External Laser Sources Matter 

The environment surrounding a modern switch ASIC is thermally demanding. High-performance switch devices can dissipate hundreds of watts of power, creating conditions that are far from ideal for laser operation. 

This challenge has driven the industry's adoption of External Laser Sources (ELS) and the ELSFP form factor. By physically separating the laser source from the switch ASIC, ELS-based architectures provide several important advantages: faceplate serviceability, improved thermal isolation, and the ability to optimize laser design independently from ASIC integration constraints. 

The industry has also established aggressive reliability expectations for these systems. The Optical Internetworking Forum (OIF) identifies reliability targets for laser sources that are significantly more demanding than those traditionally associated with pluggable optical modules³. Achieving those targets requires reliability to be engineered into the platform from the beginning. 

The Lumentum UHP Laser: Reliability by Design 

Lumentum's ultra-high-power (UHP) laser platform, which serves as the light source within its ELSFP solution, derives from the company's Raman pump laser technology deployed for more than two decades in long-haul and submarine optical networks. 

That heritage includes nearly half a million deployed pump lasers, more than 20 billion cumulative device hours in the field, and a reliability record of less than 1 FIT with zero reported laser diode field failures since 2014. 

Rather than developing an entirely new platform for CPO applications, Lumentum leveraged proven laser technology, thermal-management techniques, manufacturing processes, and qualification methodologies already validated in some of the industry's most demanding operating environments. 

The resulting UHP platform incorporates advanced thermal design, optimization for high-power operation, O-band wavelength support for silicon photonics applications, and manufacturing processes refined through years of high-volume deployment experience. Together, these design principles form the foundation of a reliability-first architecture intended for next-generation CPO deployments. 

From Design Philosophy to Measured Results 

Design philosophy ultimately has to be validated by data. 

To evaluate long-term performance, Lumentum conducted an extensive accelerated life-test program using production UHP devices manufactured on standard production lines and subjected to elevated stress conditions representative of CPO deployment environments. 

The program accumulated more than 100 million accelerated device hours with zero observed failures, while devices maintained stable operating characteristics throughout testing. These results support the reliability objectives required for large-scale AI and CPO deployments and provide additional validation of the platform's reliability-by-design approach. 

Detailed test methodology, statistical analysis, and reliability calculations are available in the accompanying white paper. 

The Reliability Decision Ahead 

The transition from pluggable optics to co-packaged optics represents one of the most significant architectural shifts in data center networking since the move from copper to fiber. 

Previous transitions were driven primarily by bandwidth and reach. The next phase of AI infrastructure growth will place increasing emphasis on reliability as well. 

External laser sources are a critical part of making CPO's reliability promise achievable, and the underlying laser platform will play an increasingly important role in determining overall system performance and availability. 

In Formula 1, the trophies go to teams that finish the race. In AI infrastructure, reliability may prove just as decisive. 

For a deeper examination of the reliability requirements of co-packaged optics, the design principles behind Lumentum's UHP/ELSFP platform, and the accelerated life-test results supporting its development, read the full white paper: "CPO Raises the Stakes: Building a Reliability-First External Laser Platform."

References
1 - Broadcom Inc., "Broadcom Showcases Industry-Leading Quality and Reliability of Co-Packaged Optics," Press Release, October 1, 2025. 

2 - LightCounting Research Note, “LightCounting : December 2025 Marvell enters the CPO race,” Dec 2025. 

3 - Optical Internetworking Forum, "Implementation Agreement for Co-Packaging," OIF-Co-Packaging-FD-01.0, 2023, Section 7.3.1.  

For more source information, see references in the white paper.