In this episode of Cable Talk, Josh talks about bend insensitive fiber, its capabilities and what it really means to your data center. When installation spaces get smaller, this product is very helpful. However, best practices still need to be followed! Data centers can utilize bend insensitive fiber to ensure insertion loss budgets are still being met.

Earlier this week I gave you some best practices with respect to installing BIF. But how do you calculate the actual installed bend radius of a cable assembly?

A good ‘rule of thumb’ that is accepted by most major cable manufacturers is the following: the optical cable bend radius is equal to ten times the outer jacket diameter of that cable.

Here is an example:

You are deploying a jumper cable that contains BIF from ANY glass manufacturer that has a 2mm outer jacket.

• 2.0mm x 10 = 20mm bend radius (remember that this is the bend RADIUS)
• 20mm x 2 = 40mm (1.6”) bend diameter (a bend diameter is sometimes easier to visualize)

I would recommend finding an object with a similar size diameter so you can visualize it more clearly. (For example, 1.6” is about the size of the cardboard tube in a standard paper towel roll.)

This would be a diameter that you could safely bend around in a long term condition without adding significant attenuation to the link.

That may not seem like a big deal – but consider that before BIF, the same safe diameter would be 3”, or about the diameter of a 20 oz. sport drink bottle.

Conclusion: The safe bend diameter with BIF is less than half compared to non-BIF glass.

Don’t be fooled. You may get stats from cable manufacturers of 10mm bend radius, 7.5mm bend radius and 5mm bend radius. This is best case scenario and only works if you deploy the glass in tight buffered form with no protection. In other words, the glass could truly bend to this small radius with respect to buffered fiber only (with no outer jacket as protection). Once that fiber is put into an outer jacket, the bend radius calculation should be calculated using the formula above.

In conclusion, BIF is a giant leap forward in fiber optic technology. Use it to your advantage but be careful to understand and follow best practices are. Don’t be fooled by the name! This fiber is just “LESS” sensitive, not “IN”-sensitive!

Last week I covered how BIF improved the performance of your data center. The key to maximizing your BIF investment is following a few best practices.

First, inspect and clean fiber optic end-faces, and take care not to deploy a fiber optic cable assembly as to create a macro bend or “kink.”

All fiber optic cable manufacturers have bend radius specifications with respect to the “installation” condition (for the short-term) and “installed” condition (the long-term). These are important considerations. You may see demonstrations of wrapping fiber around small cylindrical objects called mandrels – this is not recommended for an installed condition! Following these guidelines can help to ensure against fiber breakage during installation and cumulative light loss attenuations during the long term condition.

With the high port densities end-users face today, many installers fail to follow these best practices. High losses are then incurred throughout the infrastructure, which can lead to downtime. To make matters worse, the cabling is usually the last thing considered when finding out why downtime occurred. Next week I’ll show you how to calculate the actual installed bend radius of a cable assembly.

Earlier this week I defined terms related to “bend” performance, such as Bend Insensitive Fiber, Bend Improved, Bend Optimized and Bend Tolerant. This week, I’ll show you how BIF can improve the performance of your cabling infrastructure.

The greatest benefit BIF offers is seen when deploying fiber optic jumpers and modules containing non-jacketed, buffered fiber. That is typically where small bends in fiber optic cable occurs most easily. The BIF glass can endure a tighter bend radius with minimal addition of attenuation. BIF glass is also made to endure these tighter bends long term. Overall attenuation is the most important factor for a fiber optic cabling infrastructure.

A macro bend is a visible bend in the fiber that can cause optical power attenuation – or light loss. Historically with older non-BIF glass, macro bends will cause small light losses along the optical path. These can all add up to affect the total link loss or channel loss.

Now, with the MM BIF products that are available, these macro bends are still present but have a greatly reduced attenuation affect on the total link. Next week, I’ll give you some tips and best practices with regards to Bend Insensitive Fiber.

There are a lot of terms being thrown around related to “bend” performance in fiber optic cable assemblies, including Bend Insensitive Fiber (or BIF), Bend Improved, Bend Optimized, and Bend Tolerant. End-users confused about these terms are at risk of making uninformed purchasing decisions.

I’m going to help you de-mystify these terms by explaining what it means, how “bend” performance can potentially solve your data center problems, and the best practices you should follow for fiber optic cable installation. In essence, we’re separating the facts from the hype!

“Bend” performance affects your data center’s performance

It’s impossible to install cable so that that glass inside is positioned in a straight line – cables have to be flexible so that they can connect your data center infrastructure. Common sense, right? Unfortunately, bending the glass inside fiber optic cabling affects dB loss and decreases the overall performance of your cabling infrastructure. Bend Insensitive Fiber is manufactured to minimize the negative effects that come from bending the cable.

After you wade through the language, the technological advancements in bend performance is very important and benefits the industry greatly.

Historically, singlemode BIF has been around for years. However, making multimode BIF was impossible…until recently. Multimode (MM) BIF product is finally available! There are even different ‘grades’ of MM BIF available – depending on the glass manufacturer. The differences in MM BIF ‘grades’ are slight and the customer may or may not even be able to perceive a measureable difference. This depends greatly on the method and type of deployment. Next week, we’ll discuss how BIF improves the performance of your cabling infrastructure.