Fiber Optic Blog

When deploying a fiber network, people nowadays not only appreciate the high-speed broadband services, but the maintenance of how long it will last. After all, optical fiber is a particular type of hair-thin glass with a typical tensile strength that is less than half that of copper. Even though the fiber looks fragile and brittle, but if correctly processed, tested and used, it has proven to be immensely durable. With this in mind, there are essentially factors that will affect the longevity of your fiber network.

Installation Strains

Stress, on the other hand, is a major enemy of fiber longevity, so the protection task is passed to the cable installer, who will ensure that the use of suitable strength elements limits the stress applied to the cable to much less than the 1 per cent proof test level. The installer then needs to ensure that the deployment process does not overstrain the cable. Figure 2 below illustrates a typical crew deployment for a trunk installation. The whole process should be paid more attention to the stress.

Of the three techniques commonly used—pulling, pushing and blowing, only pulling creates undesirable stretching (tensile stress). Unlike metal, glass does not suffer fatigue by being compressed, and so the mild compression caused during pushing causes no harm to the fiber.

Surface Flaws

Optical fiber typically consists of a silica-based core and cladding surrounded by one or two layers of polymeric material (see in Figure 3). Pristine silica glass that is free of defects is immensely resistant to degradation. However, all commercially produced optical fibers have surface flaws (small micro-cracks) that reduce the material’s longevity under certain conditions. The distribution of flaws on the surface of the silica-based portion of the fiber largely controls the mechanical strength of the fiber. fiber-mart.COM fiber optic cables are well tested to ensure less surface flaws, like LC to ST fiber cable.

To conquer this, reputable fiber suppliers carry out proof testing, which stretches the fiber to a pre-set level (normally 1 per cent) for a specified duration to deliberately break the larger flaws. And the user is then left with a fiber containing fewer, smaller flaws that need to be protected from unnecessary degradation. This means primarily stopping the creation of new flaws by coating the fiber with a protective and durable material for its primary coating.

Environmental Factors

Once deployed, the local environment has a big impact on fiber life. Elevated temperatures can accelerate crack growth, but it is the presence of water that has been historically of most concern. The growth of cracks under stress is facilitated by water leading to “stress corrosion”.

You can check what the tendency of a fiber to suffer stress corrosion is by reviewing its “stress corrosion susceptibility parameter”, much more conveniently referred to as “n”. A high n value (around 20) suggests a durable fiber and coating.

Calculating How Long Your Network Will Last

Bearing in mind the three factors above, how can you calculate the lifetime of your fiber network? In general, the chances of a fiber being damaged by manual intervention, such as digging, over the same time frame is about 1 in 1,000. Quality fiber, installed by benign techniques and by careful installers in acceptable conditions should, therefore, be extremely reliable – provided it is not disturbed.

It is also worth pointing out that cable lengths themselves have rarely failed intrinsically, but there have been failures at joints where the cable and joint type are not well matched, allowing the fibers to move – for example, due to temperature changes. This leads to over stress of the fiber and eventual fracture.

Conclusion

To tell the truth, the biggest enemies to the carefully engineered reliability of fiber jumper can be either humans or animals, rather than the fused silica itself. The provided fibers are stored and coiled correctly, it is quite possible that they turn out to be stronger than we at first thought and perhaps the original flaws begin to heal with time and exposure to water under low stress levels. fiber-mart.COM offers high quality fiber cable assemblies such as Patch Cords, Pigtails, MCPs, Breakout Cables etc. All of our products are well tested before shipment. If you are interested, you can have a look at it.

Fiber optic cable is considered as one of the most effective transmission medium today for safe, and long-reach communications, and it also offers a number of advantages over copper. In general, fiber optic cable consists of a core, cladding, coating, strengthening fibers, and a cable jacket, which has been clearly introduced in the previous article. Today’s article will focus on the several materials in fiber optic cable construction, as well as their features and applications.

PVC (Polyvinyl Chloride)

Polyvinyl Chloride (PVC) is one of the most commonly used thermoplastic polymers in the world. The PVC cable is typically used for patch connections in the data center, wiring closet, and at the desktop. PVC is produced in two general forms, first as a rigid or unplasticized polymer (RPVC or uPVC). The following image shows a ST single-mode pre-Terminated cable (0.9mm PVC Jacket).

Features:

Good resistance to environmental effects. Some formulations are rated for -55 to +55.

Good flame retardant properties. Can be used for both outdoor and indoor fiber optic cables.

PVC is less flexible than PE (Polyethylene).

PE (Polyethylene)

Polyethylene is a kind of polymer that commonly categorized into one of several major compounds of which the most common include LDPE, LLDPE, HDPE, and Ultrahigh Molecular Weight Polypropylene. Polyethylene fiber has a round cross section and has a smooth surface. Fibers made from low molecular weight polyethylene have a grease like handle.

Features:

Popular cable jacket material for outdoor fiber cables

Very good moisture and weather resistance properties

Very good insulator

Can be very stiff in colder temperatures

If treated with proper chemicals, PE can be flame retardant.

Kevlar (Aramid Yarn)

The word Aramid is a generic term for a manufactured fiber in which the fiber forming substance is a long chain synthetic polyamide in which at least 85% of the amide linkages are attached directly to the two aromatic rings as defined by the U.S. federal trade commission. Kevlar fiber is based on poly (P-phenylene terephthalamide). Aramid yarn is the yellow fiber type material found inside cable jacket surrounding the fibers. It can also be used as central strength members.

Features:

Aramid yarn is very strong and is used in bundle to protect the fibers.

Kevlar is a brand of aramid yarn. Kevlar is often used as the central strength member on fiber cables which must withstand high pulling tension during installation.

When Kevlar is placed surrounding the entire cable interior, it provides additional protection for the fibers from the environment.

Steel Armor

The steel armored fiber cable, using light-steel tube, can provide maximum bend radius, strong protection and flexible cabling. Steel armor jacket is often used on direct burial outdoor cables and it provides excellent crush resistance and is truly rodent-proof. Since steel is a conductor, steel armored cables have to be properly grounded and loss fiber optic cable’s dielectric advantage. Armored fiber optic cable are often used in the outdoor direct burial cables and for the industrial environment where cables are installed without conduits or cable tray protection. The following image shows a single-mode armored fiber optic cable.

Various types of these light-steel armored fiber cables are in stock in fiber-mart.COM, including pre-terminated armored fiber patch cables, armored fiber trunk cables and field-terminated armored fiber cables for both indoor and outdoor applications.

Features:

Provides excellent crush resistance for outdoor direct burial cables

Protects cables from rodent biting

Decreases water ingress into the fiber which prolongs the fiber cable’s life expectancy

Central Strength Member

Strength member is used to increase the tensile force that will be applied on the cable during installation. Strength member will take the pulling force and will keep the fibers safe during installation. For large fiber count cables, a central strength member is often used.

The central strength member provides strength and support to the cable. During fiber optic cable installation, pulling eyes should always be attached to the central strength member and never to the fibers. On fiber splice enclosure and patch panel installations, the cable central strength member should be attached to the strength member anchor on the enclosure or patch panel.

Conclusion

When you choose to use which type of the fiber optic cables, the fiber optic cable construction, along with the mechanical and environment requirements should all be taken into account. All the above materials in the fiber optic cable construction are specifically required to meet the network infrastructure. fiber-mart.COM fiber optic cables come in various types with detailed specifications displayed for your convenient. These quality cables are designed with best-in-class performance. For more information about fiber optic cables or patch cords, you can visit fiber-mart.com.

As the quest for greater bandwidth continues and fibre optic connections within data centres and optic fibre networks increase, these

challenges must be met by choosing the right type of connectivity. This is all driven by requirements for additional switching and

routing, storage, virtualization, convergence, video-on-demand (VoD) and high performance cloud computing. All of these applications

plus other bandwidth intensive applications increase the need for transmission speed and data volume over short distances.

Optic fibre 10G transmission systems are becoming more widely used and accepted and migration paths to 40G and 100G have been

specified for optical fibre.

The IEEE 802.3ba 40G / 100G Ethernet standard provides guidance for 40G / 100G transmission with multimode fibre. OM3 and OM4 are the

only multimode fibres included in the standard.

Parallel optics technology has become the transmission option of choice in many data centres and labs as it is able to support 10G,

40G, and 100G transmission. For parallel optics to work effectively, it requires the right choice of cable and connector.

Parallel optic interfaces differ from traditional fiber optic communication in that data is simultaneously transmitted and received

over multiple optical fibres. In traditional (serial) optical communication, a transceiver on each end of the link contains one

transmitter and one receiver. For example, on a duplex channel the transmitter on End A communicates with the receiver on End B and

another optic fibre is connected between the transmitter on End B and the receiver on End A.

In parallel optical communication, the devices on either end of the link contain multiple transmitters and receivers, e.g. four

transmitters on End A communicate with four receivers on End B. This spreads the data stream over the four optical fibres. This

configuration would allow for the operation of a parallel optics transceiver which uses four 2.5 Gb/s transmitters to send one 10 Gb/s

signal from A to B. In essence, parallel optical communication is using multiple paths to transmit a signal at a greater data rate

than the individual electronics can support. This type of connectivity utilises a ribbon cable type design with all fibres aligned in

a straight array, in either a 12 fibre or 24 fibre configuration.

In addition to the cable performance, the choice of physical connection interface is also important. Since parallel-optics technology

requires data transmission across multiple fibres simultaneously, a multifibre connector is required. Factory terminated MPO / MTP

connectors which have either 12 fibre or 24 fibre array, will support this solution. For example, a 10G system would utilise a single

MPO / MTP (12 Fibre) connector between the 2 switches. Modules are placed on the end of the MPO connector to transition from a MPO

connector to a 12 Fibre breakout LC duplex or SC duplex cable assembly. This enables connectivity to the switch. 40G and 100G systems

require a slightly different configuration.

Utilising MPO / MTP connectivity has many benefits including:

High Density – multifibre connector and compact dimension of cable save space in costly data centre environments.

Reduces cable load in raised floors to existing active server/switch/storage equipment with LC Duplex interface (less cable OD, less

connections.

Pre-connectorised solution, no splicing required on site.

Reliability -100% tested factory tested in a controlled environment

Latest active equipment by Cisco / IBM / HP /Sun Microsystems has the MPO-SFP connectivity interface for Gigabit Network transmission

Rapid Deployment – factory terminated modular system saves installation and reconfiguration time during moves, ads and changes.

Next Generation Network Proof – emerging high speed protocol are going to use MTP interface- your cabling infrastructure remains

unchanged.

Difference between MPO and MTP connectors

From the outside there is very little noticeable difference between MPO and MTP connectors. Infact, they are completely compatible and

inter-mateable. For example, an MTP trunk cable can plug into an MPO outlet and vice versa.

The main difference is in relation to its optical and mechanical performance. MTP is a registered trademark and design of UsConnec,

and provides some advantages over a generic MPO connector. Since MPO / MTP optic fibre alignment is critical to ensure a precise

connection there are some benefits in utilising the MTP connector. The MTP connector is a high performance MPO connector with multiple

engineered product enhancements to improve optical and mechanical performance when compared to generic MPO connectors.

The MTP optic fibre connector has floating internal ferrule which allows two mated ferrules to maintain contact while under load. In

addition, The MTP connector spring design maximizes ribbon clearance for twelve fibre and multifibre ribbon applications to prevent

fibre damage.

Overall it provides a more reliable and precise connection.

In addition, it is also important when specifying an MPO/MTP system to ensure the correct polarity options and which cables and

outlets have female or male pins.

MPO stands for multi-fibre push-on connector. It is a connector for multi-fibre ribbon cable that generally contains 6, 8, 12 or 24 fibres. It is defined by IEC-61754-7 and TIA-604-5-D, also known as FOCIS 5. The MPO connector, combined with lightweight ribbon cable, represents a huge technological advancement over traditional multi-fibre cables. It’s lighter, more compact, easier to install and less expensive.

A single MPO connector replaces up to 12 or 24 fibre strands in a single connector. This very high density means lower space requirements and reduced costs for your installation. Traditional, tight-buffered multi-fibre cable needs to have each fibre individually terminated by a skilled technician. But MPO fibre optic cable, which carries multiple fibres, comes pre-terminated. Just plug it in and you’re ready to go.

MPO connectors feature an intuitive push-pull latching sleeve mechanism with an audible click upon connection and are easy to use. The MPO connector is similar to the MT-RJ connector. The MPO’s ferrule surface of 2.45 x 6.40 mm is slightly bigger than the MT-RJ’s, and the latching mechanism works with a sliding sleeve latch rather than a push-in latch.

The MPO connector can be either male or female. You can tell the male connector by the two alignment pins protruding from the end of the ferrule. MPO female connectors will have holes in the ferrule to accept the alignment pins from the male connector. The MPO ferrule is generally flat for multimode applications and angled for single-mode applications.

MPO connectors are also commonly called MTP® connectors, which is a registered trademark of US Conec. The MTP connector is an MPO connector engineered with particular enhancements to improve optical and mechanical performance. Significant MTP enhancements include an elliptical pin shape, a floating ferrule design, a removable housing and more. Details can be found at usconec.com. MPO and MTP connectors are compatible.

A 12-strand MPO connector features 12 fibres in a straight line, 1–12, left to right.

A 24-strand connector features two rows of fibre 1–12 and 13–24 with the white dot also indicating pin 1.

Each connector has a key on one side of the connector body. When the key sits on top, it is referred to as key up. When the key sits on the bottom, it’s called key down.

When planning your system, keep in mind that you can’t mix and match 12-strand and 24-strand cable versions.

 This article details the history and performance capabilities of the MTP connector. MTP is a trademarked brand of multifiber push-on (MPO) connector. The article is authored by technical experts from Corning Optical Communications and US Conec—the two companies that jointly developed, offer, and continue to refine the MTP connector. In our Perspective column, we welcome contributions that are opinion-based or technology-specific in nature.

Seasoned industry professionals may recall the excruciating, painstaking days of installing and connecting countless fibers, one at a time. As the number of data centers grew exponentially in the 2000s, designers and installers were tasked with managing hundreds and even thousands of single- and two-fiber connector solutions. To accommodate the high volume of connectors within ever-tighter space constraints, installers and designers were forced to create more-elaborate storage and routing solutions that came with their own sets of challenges.

Fortunately, those days are long gone—thanks in large part to the emergence of the multifiber push-on (MPO) connector. The MPO format dramatically reduced the amount of time, effort, and space required to install and deploy network technologies, particularly in parallel optic applications.Faster deployment was one thing. But installers also needed a way to fit more fibers into smaller spaces. MTP connectors addressed this challenge as well. Even before parallel optics gained popularity, installers were struggling to provision high-density applications. MTP connectors made it easier to do exactly that. In place of a 1U housing with duplex connections holding 144 fibers, the MTP housing was capable of holding 864 fibers—six times the capacity. This fiber density made MTP connectors especially well-suited for data centers with serious space constraints and/or massive amounts of cables.

GOOD TECHNOLOGY GETS EVEN BETTER

With the increasing prevalence of plug-and-play solutions, MTP connectors quickly became the format of choice for data centers, offering an alternative to LC and SC connectors. But the MTP format is more than a niche connector, with advantages that translate across a wide range of technologies beyond parallel optics. Since their launch, MTP connectors have undergone continual improvements that make them the ideal multifiber connector choice for any data center, of any size.

Highly adaptable and flexible, MTP connectors have continued to evolve to meet the emerging needs of installers, data centers, and the organizations that rely on them. Let’s take a brief tour of the key advancements we’ve seen in the MTP format over the past 20 years.

In 1999, US Conec introduced low-insertion-loss MTP Elite connector components. Corning was then able to build on this technology to introduce industry-leading, low-loss, high-density cabling solutions that delivered premier optical performance and reliable signal power. Since then, MTP insertion loss rates have continued to improve, now rivaling loss rates that single-fiber connectors saw just a few years ago.

Even beyond its value in the parallel optics space, a closer look at the MPO format reveals the full scope of its applications. To get a better understanding of big picture and true value of MPOs, we must start at the most logical place: the beginning.

MULTIPLE FIBERS MEAN MORE CHALLENGES

At the heart of the MPO connector lies mechanical transfer (MT) ferrule technology, originated by a leading Japanese telecom company in the mid-1980s for use in its consumer telephone service. This MT ferrule technology became the basis for the first MPO connector, introduced in the early 1990s.

The timing couldn’t have been better. Networks were tasked with transmitting more data, more quickly. As the need for bandwidth increased, the industry began moving toward networks and cabling with higher fiber densities—the multilane highway of data transmission. This heralded the beginning of what is known today as parallel optics, or optical transmission using multiple fibers. Because of the increase in “lanes” used with parallel optics—the number of fibers moving data back and forth—an efficient, high-density interconnect was needed. The MPO connector format succeeded in establishing a compact means to efficiently couple and decouple the high-density MT ferrule format via a bulkhead-mounted coupler. More fibers, however, also meant more installation considerations.

ADDRESSING THE CHALLENGE

To remedy the installation challenge presented by ever-increasing quantities of fibers, Corning joined forces with US Conec. In 1996, the MTP connector brand—a family of advanced MPO connectors designed for 4-, 8-, and 12-fiber ribbon applications—was released to the U.S. market. That same year, the MPO format was standardized by the International Electrotechnical Commission (IEC) and embraced by an industry thirsty for a better way to install, deploy, and manage high-density fiber networks.

Before the MTP connector came to market, it typically took two installers a full day to terminate and test 144 fibers. With MTP connectors, suddenly installers had the ability to rapidly connect 8 to 12 fibers at a time with the snap of a tool, or using a preterminated plug-and-play cable, trimming a daylong job to just a few hours. To ensure seamless connections, the MTP connector was the first MPO connector to be factory-verified and pre-engineered to proper lengths for the cable plant. This meant that less skill was required for installation, while future updates, additions, and changes to the structured cabling were dramatically simplified. Revolutionary at the time, these advancements introduced by the MTP connector eventually became the industry standard.

Cutting and splicing fiber optic cable takes a lot of time, interrupts service to downstream customers and, therefore, needs to be avoided. One way to avoid splicing is to include extra fiber cable in places along the lines, in case the company needs to change out a pole or make a road crossing.

ETC Communications (ETC) in Ellijay, GA is a family owned company that has been in business for over 100 years. ETC uses fiber optic cable to provide telephone, cable TV, and high-speed Internet to about 17,000 customers in northern Georgia and southeastern Tennessee. They typically include 25 to 50 feet of spare cable approximately every fifth span. The question is…

HOW TO STORE THE EXTRA CABLE?

Option 1: Coiling

Extra cable can be coiled and attached to the pole. However, coiling can cause light loss. In a fiber optic cable, information is transmitted by light that travels through the glass fibers in the cable. Some light is lost when the cable is bent, especially when it is cold. “It does get cold here about four or five times a year,” says  Van Powell, Construction Manager for ETC,  “and when I say cold, I mean below 10°F. When it got below 18°F, we used to have excessive light loss in our long cable runs with lots of coils.” In addition to possible attenuation, coils stored on utility poles take up space and can be damaged by linemen climbing the pole.

Option 2: “Snowshoes”

ETC uses “snowshoe” storage systems to store extra fiber on the line. Snowshoes allow for the slack to be stored out in the span, reducing likelihood of damage while eliminating additional charges for using pole space. ETC’s storage systems have a turning diameter of about 20 inches. Two units are installed at an appropriate distance and the cable is stretched between them. This greatly reduces the number of turns–from hundreds to two and solves the problem of light loss.

The Opti-Loop® Storage System Advantage

ETC has been using products from a couple of different vendors, and last fall, they gave the Hubbell Power Systems, Inc. (HPS) Opti-Loop®  storage systems a try. Powell explains, “There are probably 15 or 20 different companies that make similar systems and we’ve used different kinds in the past. Last year, Phil Peppers, ProCom Sales, brought us five sets of the Opti-Loop storage systems to try them. We put them up, and we like them.” While fiber optic snowshoes, in general, solve the problem, the Opti-Loop storage systems have an advantage: they are very easy to install. “There is a twisted aluminum support wire on the poles. That is what holds up the fiber optic cable. We bring in a bucket truck and attach each snowshoe to that cable with a bolt and clamp. The fiber optic cable is attached to the snowshoes with zip ties and along the support wire with lashers (little coils). It onl