Glass Fiber

Glass fiber is the most common type of fiber available, with companies such as Corning and Siecor producing billions of meters per year. Common industry-standard glass fibers are differentiated by the diameter of the core: larger cores allow more modes to propagate; smaller cores allow fewer. Glass fiber is available in three common sizes: two multimode fibers and one single mode fiber. Multi-mode fibers have larger cores and allow many modes to travel through the fiber. The two standard sizes for multi-mode fiber are 62.5/125 mm, and 50/125 mm.

The first number indicates the core diameter and the second number indicates the cladding diameter. Single-mode fibers have cores so small that only one mode of light enters the fiber. Most single-mode fibers are 9/125 mm, but some have 8 mm cores.

Glass fibers are lightweight, durable, and fairly inexpensive. They make up most of the installed base of fiber-optics in the world. Single-mode fiber accounts for all of the longhaul telecommunications fiber.

Plastic Optical Fiber (POF)

Plastic fiber has been around for about 20 years and makes up only a small percentage of the total fiber in the world today. Most plastic fiber is used in Japan and Europe. The two major manufacturer of POF today are Mitsubishi in Japan and Boston Optical Fiber in the US. Several other smaller Japanese vendors also manufacture POF.

POF is easy to work with because of its large 980/1000 mm diameter. As a result, component, connector, and labor costs are all minimal, making a plastic fiber-optic link comparable to the cost of copper wire.

Hard Clad Silica (HCS)

HCS fiber has a glass core and a plastic cladding, giving it the qualities of both materials. This fiber is used even less than plastic fiber: SpecTran Specialty Optics Corporation being the most prom-inent manufacturer in the US and Torray being the most prominent one in Japan. HCS is the most durable of fibers and is relatively easy to work with. It has a 200/240 mm diameter, and is available in riser and plenum versions that meet environmental standards.

If the diameter of the fiber core is smaller than the light emitter or larger than the photodiode detector, power coupled from the transmitter into the fiber or power coupled from the fiber into the receiver can be lost. For this reason, the transmitter and receiver must be optically matched to the fiber’s diameter.

Exactly how much pulling force should be used for fiber optic cable installation?

Here is a brief answer.

The pulling force must be kept below a designated limit for the specific cable being installed. For outside plant (OSP) fiber optic cables, the limit is usually 600 pounds. For indoor fiber optic cables and other types of cables, the limit is usually 300 pounds.

The key point is – Keep the pulling force UNIFORM.

Why is keeping pulling force uniform so critical? The short answer is that most fiber optic cables cannot handle high impact load. Fiber optic cable strength member is purposely designed to handle the pulling force and facilitate fiber optic cable installation. Never pull the glass fibers directly. Never jerk a fiber optic cable.

Power equipment should never be used for indoor fiber optic cable installation, since the limit of allowable pulling force for indoor fiber cables is so small that you can easily break the fibers.

March 15, 2007 — BICSI reports that its 2007 Canada Conference was “a most memorable event,” featuring educational presentations, informative exhibits and networking opportunities for participants. BICSI President John Bakowski announced that the conference hosted nearly 1,000 participants.

According to a press release, attendees and exhibitors alike bestowed highly positive reviews of their participation at the conference. “This is one of the best BICSI conferences I have ever been to,” said 12-year member Joanne Bazinet-Brown, RCDD. “I met a lot of new exhibitors and the educational sessions were fresh and interesting.”

“The exposure we have received has been phenomenal,” added Wade Muri, of Genetec. “This is our first time exhibiting at a BICSI conference, and we definitely will plan on coming to future shows.”

The conference’s General Session started with BICSI government relations consultant Richard Reed, RCDD/OSP specialist, giving an update on municipal and provincial legislative issues that are affecting the industry in the Canadian region.

Jeffery Beavers, RCDD/OSP specialist, followed with a presentation on the design and planning for the Louisiana Superdome reconstruction project from a telecommunications standpoint. Beavers outlined the difficulties and delays that had to be overcome in repairing the structure after the devastation suffered from Hurricane Katrina.

The closing keynote address was given by Captain Larry Brudnicki, who delivered a presentation incorporating stories and lessons learned from his experience directing U.S. Coast Guard rescue efforts in events described in Sebastian Junger’s book, The Perfect Storm.

Brudnicki stressed to conference members the importance of “having a plan B” in life and business decisions. “Just as I had to make life and death decisions in rescuing the crew members of that ship, it is vital for you to develop processes of assessing risk and choosing which route you will take to achieve your project goals,” he said.

Also, throughout the Canada conference, attendees stopped by the BICSI Cares booth to offer donations for that charity. The Western Society for Children, an organization that focuses on delivering basic life needs to children and families who deal with the difficulties of birth disorders and disabilities throughout Greater Vancouver and British Columbia, benefited tremendously from these acts of giving, reports BICSI.

The BICSI Cares presentation was hosted by newly inducted BICSI Committee chair Christine Klauck, RCDD/NTS specialist. According to the release, “there were looks of surprise, joy and a few tears shed” as members of the Committee presented representatives of the Western Society for Children with a check for CAN$10,700.

“I am proud of all the conference participants for showing their generosity to help BICSI Cares make a difference in the lives of all children here in Western Canada,” said Klauck.

Well, the short answer is YES for premises and local area networks.

Single mode and multimode fibers have different network applications, because they have very different optical-performance attributes.

In the design of premises and local area networks the decisive factor is the overall cost of all components. The large core of multimode fibers (50um or 62.5um) has distinct advantages: it enables low loss connection and facilitates fiber-to-fiber and fiber-to-transceiver alignment. This makes it best suited to premises and local area network applications.

Premises and LAN networks include three major components: fibers, switch equipment and optical transceivers. Since switch equipment are independent of fiber type, transceiver cost has the greatest impact on fiber optic network budget.

So now let’s take a closer look at the four major types of optical transmitters and their difference in cost and optical performance.

DFB(Distributed Feedback) laser: DFB lasers are the most expensive lasers compared to the other three type of lasers. Its high-power and highly focused beam makes efficient power coupling into the 9um small core of single mode fiber. DFB lasers are most suitable for long haul single mode fiber applications. 

FP(Fabry-Perot) laser: FP lasers are also expensive compared to LED and VCSEL light source. Its high-power and highly focused light beam also make it most suitable for long distance single mode fiber communication applications.

LED: LEDs have low launch power and broad spectrum. Its large numerical aperture and low power level make it unsuitable for single mode fiber applications. But it traditionary offers an inexpensive solution for short-reach network applications, though now it is fading out of favor in premises networks due to its limited bandwidth.

VCSEL: Vertical-Cavity, Surface-Emitting Lasers (VCSEL) do have a low numerical aperture which makes coupling into 9um single mode fiber possible. But since it has a large active area (15um) and low source power, the efficiency of coupling VCSEL lasers into single mode fibers is very low. So VCSEL has become the sweetheart for short-reach multimode fiber premises network applications.

The standardized 1,310-nm FP and DFB laser transmitters, required for transmission over single-mode fiber, are restricted by their inherent composition to a lower data rate boundary of 1,000 Mbps. By contrast, low-cost 850-nm VCSELs that are suitable only for transmission over multimode fiber have a broad data-rate operating range–from 10 Mbps up to 10 Gbps. Therefore, the combination of multimode fiber and 850-nm VCSELs constitutes a low-cost solution that facilitates the current needs of a low data rate network, while also future proofing that network by providing a clear migration path from 10 Mbps to 10 Gbps on the same fiber.

The basic techniques for pulling fiber optic cable differs little from the approach used to pull copper or aluminum. However, fiber responds differently than copper or aluminum when pulled.

Caution One: Avoid Measurement Error!

The first step in pulling fiber optic cables is to measure and cut the material. Inaccurate measurements are a disaster in fiber cable installation. Fiber optic cable splices are way more critical than metal cable splicings. Minimum loss budget must be maintained in a fiber optic cable installation project. Thus, assumptions and guess work simply do not work.

Caution Two: Do Not Exceed the Allowed Pulling Load and Fiber Bending Radius!

Although fiber optic cables have been designed to protect fiber, it is still more easily damaged than metal cables and requires greater care during the cable pulling process. You simply can not afford to break fiber cable during the pulling process!

The physical characteristics of fiber optic cable must always be borne in mind during the fiber cable installation process. The two most important characteristics are tensile stress (pulling load) and bending radius.

The most common form of damage is a broken fiber in a fiber pulling process. In addition to that, fiber also can be cracked from too much tension. Always respect the fiber cable specifications during the process of fiber optic cable pulling!

What is a index matching gel?

Get index matching gel here.

Will index matching gel dry out? leak out? expire? Blow away?

The gel in the back of the UniCam Connector is designed to withstand normal usage for a life in excess of 20 years. There have been no reports of the gel drying out, leaking or failing in any way. For more information, refer to AEN 46,”The Longevity and Use of Index Matching Gel in the UniCam® Connector and the CamSplice™ Mechanical Splice.”

Fiber optic cable installation is a specialized task and this is a brief review of  cable installation practices for a bunch of different applications.  You can find more Fiber Optic Technical Tutorials.

Fiber Optics For Sale Co. provides Fiber Optic Cable Pulling Products for cable installation and you can also find cable pulling lubricant here.

Most methods for installing optical cables have been adapted from those used for copper cables.

Outdoor fiber cables are laid along rights of way leased or owned by telecommunications carriers, such as along a railroad or highway, which are well marked after the cables are installed.

The fiber installation approaches depend on the types of cable being installed.

1. Submarine fiber optic cables. Submarine optical cables are laid from special ships built for that purpose. Submarine cables are buried in trenches dug on the sea floor if the depths are less than 200 meters. Alternatively submarine cables are laid directly on the ocean floor in deep ocean basins.
2. Direct-buried Fiber Optic Cables. Direct-buried fiber cables are laid in a deep trench dug with a cable plow, which is then covered with dirt and marked with fiber optic cable marker tapes.
3. Cable ducts and innerducts. Cable ducts are plastic tubes laid in trenches dug for that purpose, then covered over. The ducts typically are directly covered by soil, but sometimes may be encased in concrete to add structural integrity and prevent service disruptions. The ducts are installed without cables inside. Duct routes may be direct between end points, or may be routed through a series of underground access points at manholes.
4. Outdoor cables. Outdoor cables are installed in ducts by threading a pull rope through the duct, attaching it to the cable, then pulling the cable through the ducts.
5. Self-supporting aerial fiber cables. Self-supporting aerial cables (or called figure 8 cables) are suspended directly from overhead poles. Other aerial cables can be suspended from messenger wires – strong steel wires strung between poles. If a messenger wire is used, the aerial cable is lashed to it with a special lashing wire running around both the cable and the messenger wire. This is a very common installation for many overhead fiber cables.
6. Indoor fiber optic cables. Indoor fiber optic cables can be installed within walls, through cable risers, or elsewhere in buildings. Note: Only special cables designed for installation under carpets should be laid on the floor where people walk.
7. Indoor Plenum rated fiber optic cables. Only plenum rated indoor fiber optic cables can be installed in ducts, plenums, and other spaces used for environmental air.
8. Light-duty fiber cables - distribution cables. Light duty cables are installed in indoor applications for light use.

Splice trays are necessary for holding and protecting individual fusion splices or mechanical splices.

Splice trays are available for all different kinds of splices, such as mechanical splices from 3M, Corning, AMP and Siemon company, bare fusion splices and heat-shrink fusion splices, and so on.

Important!

Normally splice trays should be matched to the type of splice used. A splice tray designed for holding mechanical splices usually can not be used for bare fiber fusion splices or heat-shrink fusion splices. Although there are splice holding chips you can purchase to make them work, it is not the ideal way.

Standard splice trays can hold up to 12 splices and you can use several splice trays together for higher strand number fiber optic cables. The splice tray has room for mounting fiber splices and excess fibers.

Fiber loose tubes enter the splice tray at one end and are secured to the splice tray. The loose tube stops at the splice tray end and individual fibers are exposed and spliced inside the splice tray.

NOTE: Bare fibers without protection tubes should never be exposed outside of a splice tray. When splicing a large fiber optic cable with more than 12 fiber strands, proper buffer tube splitters should be used when routing bare fibers to another splice tray.

Important!

Be very careful when mounting the splices inside the tray. Minimum fiber bending radius requirement should always be observed.

The following is a sample picture of a splice tray with fusion splices mounted inside.

Fiber optic splice enclosures are used to protect stripped fiber optic cable and fiber optic splices from the environment, and they are available for indoor as well as outdoor mounting.

Outdoor fiber optic enclosures are usually weatherproof with watertight seals.

In a typical wall-mounted splice enclosure, fiber optic cable is supported by cable ties, and the cable strenght member is securely fastened to the enclosure’s support. Metallic strenght members must be grounded securely.

The cable jacket(sheath) stops at the splice enclosure’s cable ties. Optical fiber tubes, individual tight buffered fibers, or pigtails are supported by the tube brackets and continue to the splicing trays.

Individual optical fibers should never be exposed outside of a splice tray. Fusion splices or mechanical fiber optic cable splices are contained in the splice trays.