The impact of VCSEL misalignment on reliability in today’s data centers.
The weak link in an optical module’s reliability chain are the VCSELs. Here’s why, and how you can compensate to ensure reliability without adding complexity and cost.
Think about your standard optical device, connected to a fiber optic line. This connection needs to be as carefully and accurately aligned as possible, because when you misalign, you lose light. The more accurately you can align the two, the more light energy you can couple from the source into the fiber itself. After all, once you are misaligned, you either increase bias current to increase light output or scrap the unit. .
If you can’t adjust enough for the connection, the only answer is to increase energy or power on the laser in order to compensate. Now you’ve caused another problem – as the current increases to increase power, the less reliable the VCSEL is. Every time you change the power of the VCSEL, increasing the bias current, you’re negatively impacting the reliability of the transceiver module. In fact, just a 2mA increase will decrease reliability by 4x.
As this is true even for one VCSEL, think about the impact on a product that has as many as 8 VCSELs. Each one will need to be lined up with accuracy and control, or you will need to increase the bias current, directly impacting reliability.
How Does the Added Consumption Impact Reliability and Costs?
Today’s data centers are being pushed to perform better, faster, with more availability, and for more consumers than ever before. These data centers have hundreds of thousands of optical modules and rely on metrics such as the Mean Time to Fail, or the Time to 1% Fail, in order to establish revenue, gauge reliability and predict business growth.
The amount of bias current has a directly negative effect on these numbers. Higher Bias current = less reliability. In turn, this has a number of tangible and intangible costs attached. Tangible considerations include the cost to replace transceiver including, maintenance, and labor. Intangible costs can be even more devastating, including the very real cost of downtime, such as customer frustration and churn.
Manually Aligning VCSELs
To tackle these challenges head on, transceiver manufactures are highly motivated to improve alignment, but the costs of performing this task manually can be crippling in and of themselves, and still provide sub-par results.
First, it’s time consuming to physically take a fiber, power up the module during production and then attach it to the laser or the VCSEL array. On top of this, accumulated tolerances make this a difficult process to accurately guarantee. All that needs to happen is for a small error to exist on the x or y axis, or for the fibers to be tilted, and your alignment is still going to cause issues achieving the right amount of light energy.
The AuraDP Difference
DustPhotonics technology was built to address this exact problem. It provides a simple, consistent alignment process for all devices, in a passive and accurate way using a ‘snap and go’ mechanism.. Eliminating the need to boost the power on any of the lasers, you get 90% coupling efficiency across all devices, photo detectors and lasers. This eliminates the need to adjust the VCSEL bias current altogether.
As well as the intangible savings on higher reliability and less downtime, the tangible costs are incredibly clear for a high-performance data center.
More Power not Working Out for You? Try More Accuracy Instead
Manually aligning VCSELs is difficult. Why turn to adding power, cost and complexity when you can turn the existing system of alignment into a passive process that gets it right every time?
Raising your bias current is not a sustainable way to improve performance, and it’s certainly having a negative impact on your reliability. Instead – sidestep the stress of VCSEL alignment with an effortless technology that gets you more out of your existing connections.