Can the reliability standards for data center optical modules/devices be relaxed?
Dec 11, 2025|
◆Data center optical module power consumption requirements
Differences in the working environments of optical modules in telecommunications and data centers
There are three main differences:
Different operating temperatures
Telecommunications applications experience daily temperature variations due to diurnal temperature differences, as well as seasonal temperature variations due to the changing seasons. Optical modules need to adapt to these variations. Telecommunications-grade applications are divided into indoor and outdoor environments. Indoor environments are 0~70℃, commonly known as commercial grade; outdoor environments generally require -40~85℃, commonly known as industrial grade.
Data centers are different; their optical modules only need to undergo a 10℃ temperature cycle, which is extremely stable.
Can we lower the requirements for high-temperature and high-humidity lifespan reliability testing that we demand every day in data centers?
Different product lifecycles
Telecommunications-grade applications, once deployed, are expected to last for decades; typical reliability lifecycles are designed and evaluated based on 20 years.
Data center applications are typically replaced every two to three years.
Okay, so I make something that won't break down for 50 years, but you use it for two years and then throw it away? Can we lower the lifespan requirements a bit?
Different Redundancy Designs
Telecommunications applications have line redundancy designs, but the redundancy is not large. Backup communication switching is used on critical lines. However, we often hear news reports of tens of thousands of users being affected by the failure of a single main device, impacting their phone calls and internet access. In short, the inability of optical modules to function is a critical issue. Data centers have much wider redundancy, especially since over 90% of servers are cloud servers. Therefore, users are almost unaware of any optical module failure. For suppliers, even if some optical modules fail randomly, they can simply be replaced.
So, can the reliability requirements for optical modules be relaxed? From an application perspective, relaxing reliability requirements has little impact on customers. The next question is: what should be relaxed? How should it be relaxed? And why should it be relaxed?
Major Failure Components and Causes of Failure in Optical Modules
Facebook released failure statistics for a 100G optical module, showing that 97% of failures were laser-related, with most occurring within three months of the laser's initial operation. If the majority of failures occur within three months, should the definition of early failure be adjusted? Among the failed lasers, the failure rate of DFBs (Digital Bulbs) is significantly higher than that of EMLs (Electromagnetic Laminates) (several hundred times greater). This raises the question of whether Dr. Zeng from Facebook believes that DFBs in direct modulation mode are more prone to failure than DFBs that emit light continuously (just as a stationary wire can last a long time, but repeated bending will easily break it).
Therefore, for lasers, which are the primary failure targets, should reliability testing be increased at the laser wafer level? If it's related to modulation mode, should long-term lifetime testing include verification under modulation mode?
Relax reliability requirements
If reliability requirements are to be relaxed, specifically, should we reduce the number of test items, lower the test conditions, shorten the test time, or reduce the number of test samples?
Reduce the number of test items?
In fact, there are not many reliability test items. Even if one or two are removed, they are not the high temperature and high humidity life test that optical module device manufacturers care about. Rather, they are some less important items. Reducing the number of test items is meaningful, but not very significant.
Reduce testing conditions?
This is possible, but how much to reduce requires data analysis to find the appropriate testing conditions.
Compress testing time?
How about 500 hours, not 5000 hours, not 2000 hours, not 1000 hours, but just 500 hours? This way, reliability testing won't cause a long product launch cycle.
Intel gave an interesting answer: based on the GR468's acceleration factor, a 10-year lifespan can be tested in 6 weeks, using an acceleration factor of 100x.
Then, if we increase the reliability testing temperature to 130℃, the acceleration factor becomes 1000x, and a 17-year lifespan can be tested in one week.
This seems to compress the time even more, right?
Could we reduce the long lifespan testing time by increasing the sample size, for example, 500 samples for 500 hours of high temperature and humidity?
Reduce the sample size for reliability testing?
Broadcom has a statistical analysis of the deviation in lifespan prediction caused by different sample sizes. The conclusion is that "no matter what technology is used, one cannot expect to reduce the number of samples to achieve the goal of reducing reliability requirements," because a small sample size itself introduces bias.
If reliability requirements are to be relaxed, how should the standard be defined?
20 years ago, GR468 was a benchmark in the optical communication industry. Actually, there was a reliability standard called GR3013 for short lifecycles as early as 2004.
However, this new standard with relaxed reliability requirements is little known, at least I've heard of it.
This afternoon, major manufacturers were still using GR468 for analysis.
So, should the relaxed reliability standard be a completely new standard series? That carries the risk of something similar to GR3013-the industry spends a long time developing standards, and then they remain unknown…
Option two: modify GR3013 and implement it, then promote it.
Option three: develop a more lenient version of CR468 suitable for data centers.
This is a very specific issue in the industry chain-how to implement it?
The fundamental question is: "If reliability standards are relaxed, will costs be reduced?"
For data center operators, what do they gain by relaxing reliability requirements? Low cost is their core objective. Lasers have the highest failure rate. However, manufacturers like Sumitomo and Broadcom, which produce lasers, used text, formulas, and diagrams to convey the message that relaxing reliability requirements does not reduce costs. In fact, it increases costs if the reliability verification process for laser wafers is modified.
For lasers, reliability relies on continuous technological improvement. Relaxing reliability requirements is not a way to reduce costs. As one sentence in Broadcom's presentation stated: "Think about other ways to reduce costs..."