Why Network Designers Specify Particular Brands of Optical Fiber for Their Systems

People sometimes wonder why network designers specify particular brands of optical fiber for their systems, such as Corning SMF-28e. Usually, the designer wants to guarantee the highest optical performance in the network for his customer and insure fiber compatibility. Incidentally, all of the cables provided by FIS/TLC contain genuine Corning fiber.

On a large network installation, there may be several installation contractors working on the project. Using compatible fiber is essential for ensuring that the part of the network you install will work correctly with the rest of the system. Before you bid a job, make sure that your cable vendor can provide the correct fiber.

Singlemode Compatibility Issues

There are several domestic fiber manufacturers that produce "standard" SMF-28e singlemode fiber. These companies spec their fiber as being fully compatible with or equivalent to "standard" singlemode fiber. However, if you are adding "off-shore fiber" to an existing network, you may run into some compatibility issues. These include:

• Operating Wavelengths: Corning has enhanced their product to carry wavelengths from 1280-1700nm. However, some "off-shore" fiber still has an attenuation peak in the 1400-1500nm window. These fibers won't be compatible with many of the new Fiber-to-the-Home networks that need to operate at around 1490nm.
  
  
• Index of Refraction (IR): The IR of some "off-shore" fibers is slightly different from the IR of Corning fiber. This difference can cause additional optical loss in a system where the two different fibers meet. This can also cause confusing OTDR results. Under certain conditions, a slight difference of IR between two spliced fibers can produce a "gainer" on an OTDR trace. A "gainer" is an OTDR splice event that appears to gain optical power through the splice instead of showing a slight loss.
  
  
• Splicing: Fusion splicing an "off-shore" fiber to a Corning fiber may require you to set custom splicing parameters in order for your fusion splice machine to fuse properly.

Multimode Considerations

Compatibility problems are not confined to singlemode fiber. There is an issue with multimode fiber regarding "On-Center Laser Launch."

Newer Corning InfiniCor multimode fibers are designed to work in laserbased protocols, such as Gigabit Ethernet, without requiring mode-conditioning patchcords. These new fibers allow you to launch a laser directly into the center of the fiber core without inducing modal dispersion at fast transmission speeds. However, older multimode fibers, and some "off-shore" fibers, won't work in a gigabit network without some sort of off-center launch mode conditioning. If a non-compatible multimode fiber is placed directly into a gigabit network, the network's transmission rate will drop significantly.

Optimizing Fiber Optic Connectors and Splices with an OTDR

An OTDR is most commonly used to test large fiber optic links. However, an OTDR can also be used to maximize i.e. "optimize" the light throughput of a quick-termination connector. Similarly, an OTDR can be used to optimize a mechanical splice that is used to join a pigtail to the field fiber. "Mini" OTDR's are especially useful for this purpose since they are compact and easy to use.

Optimizing connectors and splices involves taking advantage of your OTDR's real-time trace capability. As is always the case with when using an OTDR, you will need a launch cable that is longer than the OTDR’s “dead-zone.” In most cases, a 30-meter patchcord or a 30-meter pulse suppressor will provide the length that you need.

The following explains the general steps involved, although these steps can vary according to the features of your particular OTDR.

1. After attaching the launch cable to the OTDR, switch the OTDR to Short Pulse mode.

2. Next, attach the other end of the launch cable to the connector (or pigtail) by using the appropriate mating sleeve.

3. Press the Scan button on your OTDR to begin a trace. Initially, you will see only a short trace that depicts your launch cable.

4. After stripping and cleaving your field fiber, carefully feed the fiber into the connector.

You will see the scan of the field fiber rise up the OTDR screen. This shows that the optical connection is improving as the field fiber approaches the launch fiber.

If your OTDR has a 2-point loss feature, you can use this feature to provide a good estimate of the light throughput of your connector or splice. This involves placing the OTDR's A and B screen cursors immediately before and after the spike. This spike was caused by the mating of the connector and the fiber.

This optimization technique can help you to reduce labor time and scraped connectors or splices. It will also serve to verify that you have achieved the proper connectivity before the fiber is permanently secured.

Also, when using a Bobtail Quick Term Connector you can use a simple visual fault locator to optimize the connection. The Bobtail has a translucent section that allows the visible light of the VFL to shine through the connector body as you insert the field fiber. Once the field fiber reaches the internal stub fiber, the light should no longer be visible. This indicates that a proper mating of the two fibers has been achieved.

Fiber Backbone Security Underground vs. Aerial

Common Misconceptions

When addressing Fiber Backbone Security Underground vs. Aerial the first thought that many people have is that buried cable is more secure. Covered by dirt, asphalt or concrete, it would seem to take some effort for a terrorist to locate where the buried cable is, and then to dig down to gain access to it.

In contrast, aerial cable, being suspended in the air, seems an easy target for any weapon fired from the ground, or anyone capable of climbing a utility tower or pole.

However, upon closer analysis, aerial installations actually provide more security. This has to do with fiber's tremendous bandwidth, the relatively low cost of aerial installations, and the alternate cable routes that are possible with this type of installation.

Security Strategy - Minimization vs. Prevention

The analysis of Fiber Backbone Security Underground vs. Aerial may seem purely academic, given that there are so many places that terrorists can access fiber in a huge national network. Even underground systems provide access via manholes, hand holes, above ground splice pedestals, and so forth. Prevention, at least at this point in time, appears to be impossible.

Since we can't prevent attacks, the security strategy must be to minimize the disruption that would result from such attacks. The way do to this is to reroute data from destroyed fiber optic cables to other fiber optic cables and networks that remain intact. The main reason this is possible is because of the tremendous bandwidth of fiber, and it's capacity to take on the additional load.

Some of this alternate routing capability already exists in the aerial fiber optic cable that is currently in place. Furthermore, today's telecommunications carriers are building even more aerial capacity by partnering with power companies and sharing their rights of way. These carriers are motivated by the fact that underground utility corridors are getting more crowded, and obtaining rights of way for buried cable is getting increasingly expensive. In contrast, aerial installations and repairs are faster, easier and less costly. According to most estimates, aerial construction is as much as 40 to 50 percent less expensive than the underground alternative.

Creating a like number of alternate cable routes underground would likely be an impossible task, considering the amount of digging and boring that would be necessary, not to mention disruption to above-ground facilities.

Some Issues Remain

Thousands of alternative cable routes aren't helpful if there is no disaster recovery plan in place, which includes procedures for rerouting telecommunications in the event of a catastrophe. Unfortunately, only the telecommunications carriers know the physical route that data takes through their networks. For various reasons, including competitive concerns, carriers have been very reluctant to share this information.

Federal authorities are now pressuring carriers to release this information so that effective disaster recovery plans can be developed.

Another major issue is that there are some fiber backbones in the U.S. where huge amounts of data are channeled with no redundant routing available. For example, there are two bridges over the Mississippi River that carry most of the bandwidth distributed along the eastern U.S. At present, no alternate cable route exists. This is one instance where buried cables could, in fact, prove beneficial by providing alternate fiber optic distribution channels under the riverbed.

FIS Fiber Optic Research Park

At FIS, we share your sense of urgency. We’ll do whatever it takes to get the product to you quickly, even overnight if necessary. In the unlikely event we don’t have the item you need, we can source it for you. If the item you require is truly unique, we can design and manufacture it for you. What you thought was a hopeless situation is now "problem solved!"

How do we do it? By using the many resources of the FIS Research Park. In addition to housing one of the largest fiber optic inventories in the nation, the Park is home to FIS and its affiliate companies. Check out the diverse technologies and capabilities that make FIS so unique.

FIS Manufacturing Operations - FIS manufactured products include test devices, patchcords, connectors, security equipment and more. Buy "factory direct" and save!

FIS Custom Services - Our Customization Team can modify standard products to fit your precise needs. Or, they can create a product for you from scratch! Custom work includes custom terminations, coupler modules, preloaded racks, and much more.

Custom Packaging - Want to break out a large order into smaller quantities? No problem! We can even repackage items individually in bar-coded blister packs for easy shipping, inventory and storage.

Rapid Prototypes - Solid-object, 3-D printing enables us to provide prototypes of any custom parts you may require. You get to see, touch and feel the item before doing a production run.

Laser Etching - Have your company name, logo, or inventory control number indelibly inscribed on your equipment.

Vinyl Overlays - Equipment front panels can be designed or updated with our colorful custom-designed vinyl overlays

R & D - The lights at the FIS Research Labs burn late into the night, and the townspeople are beginning to worry. After creating the Bobtail™, what new creation will FIS unleash upon the world? *

*The famous Bobtail Quick Term Connector was conceived, designed and manufactured at FIS in 2004. Fill out a form for a free Bobtail sample or all 800 5000 FIS.

Molding Solutions Inc. (MSi) - MSi specializes in creating custom molded parts for a wide range of industries and applications. MSi customers are involved in each stage in the process, from design and prototyping through final manufacturing.

Force Guided Relays Int'l (FGR) - FGR manufactures and distributes electro-mechanical safety relays worldwide. The company will soon add innovative optical safety relays to its product line!

American Standards Lab (ASL) - ASL tests connectors and patchcords to ensure conformance to GR326 standards. The company also provides quality assurance services for other Technology Park members.

FIS Blue, Inc. - Serving the U.S. Military and Broadcast industry, FIS Blue provides specialized connectors and patchcords for mission critical applications. Products include TFOCA II and Expanded Beam connectors and cable assemblies.

FIS is 'Cable Ready' - Our custom cable manufacturing facility, The Light Connection (TLC), can provide Corning fiber jacketed in any color of the rainbow, in any length you require. Custom imprinting too!

Technical Support Team - Have you ever experienced work delays due to technical issues? Imagine the time and money you can save if you call these guys first!

Copper Division - The next time that you need copper jumpers, jacks, or cable in a flash, just call FIS. We can deliver the items you need straight to your door, often in less time than it takes you to buy it locally!

Purchasing Department - FIS sources worldwide to provide you with the products you need. Our high-volume purchasing enables FIS to benefit from special pricing, which we pass on to you.

Consumer Research - FIS continually conducts customer surveys and focus groups to stay in tune with our customers' needs and preferences.

International Division - FIS is known worldwide for its quality products and excellent customer service. In fact, the U.S. Department of Commerce presented FIS with the highly coveted Exporter of the Year Award in 2007.

FIS China - For large "commodity" orders, FIS offers the services of its China affiliate. You get speed, quality and great pricing on patchcords, couplers and much more.

Fiber Optic Equipment Rentals- How much money could you save by renting equipment from FIS instead of purchasing it? Call us to find out!

New 2 You Department - Save BIG by purchasing "like new" equipment from FIS. Trade your own used equipment for cash!

Fiber Optic Training Division - Learn to work faster and more efficiently with our hands-on Fiber Optics I and II Course. Check out our website for schedule and locations, including our Brightside training facility in the Adirondacks!

FIS Security Division - How do you monitor an area 50 miles long? By taking advantage of the extended range of FIS fiber optic cameras and perimeter monitoring systems!

Fiber Optics to Go™ - You can purchase FIS fiber optic products at a growing number of contractor retail locations around the country!