Fiber Transceivers – Page 153

The Application of EDFA

Optical amplifiers are the critical technology for the optical communication networks, enabling the transmission of many terabits of data over distances from a few hundred kilometers to thousands of kilometers by overcoming the fiber loss limitation. As the first optical amplifier commonly used in optical communications systems, EDFA has resulted in a dramatic growth in transmission capacity with the deployment of WDM systems. Be equipped with the features of high output power, high gain, wide bandwidth, polarization independence and low noise figure, EDFAs have become one of the key components used in the new-generation optical communication system. So what is EDFA? Do you know EDFA working principle?

What Is EDFA?

Erbium-doped fiber amplifier (EDFA) is an optical repeater device that is utilized to boost the intensity of optical signals being carried through a fiber optic communications system. An optical fiber is doped with the rare earth element erbium so that the glass fiber can absorb light at one frequency and emit light at another frequency.

EDFA Working Principle

The erbium-doped fiber (EDF) is at the core of EDFA technology, which is a conventional silica fiber doped with Erbium. When the Erbium is illuminated with light energy at a suitable wavelength (either 980 nm or 1480 nm), it is motivated to a long-lifetime intermediate state, then it decays back to the ground state by emitting light within the 1525-1565 nm band. The Erbium can be either pumped by 980 nm light, in which case it passes through an unstable short lifetime state before rapidly decaying to a quasi-stable state, or by 1480 nm light in which case it is directly excited to the quasi-stable state. Once in the quasi-stable state, it decays to the ground state by emitting light in the 1525-1565 nm band. This decay process can be stimulated by pre-existing light, thus resulting in amplification. EDFA working principle is shown in the Figure 1.

Baisc configuration of EDFA

EDFA configuration is mainly composed of an EDF, a pump laser, and a component (often referred to as a WDM) for combining the signal and pump wavelength so that they can propagate simultaneously through the EDF. In principle, EDFAs can be designed such that pump energy propagates in the same direction as the signal (forward pumping), the opposite direction to the signal (backward pumping), or both direction together. The pump energy may either be 980 nm pump energy, 1480 nm pump energy, or a combination of both. Practically, the most common EDFA configuration is the forward pumping configuration using 980 nm pump energy, as shown in the Figure 2.

Application of EDFA

After learning what is EDFA, and EDFA working principle. Next, we’ll discuss application forms and application fields of EDFA.

Forms of application

Booster Amplifier

When used as the booster amplifier, EDFA is deployed in the output of an optical transmitter to improve the output power of the multi-wavelength signal having been multiplexed, as shown in Figure 3. In this way, distances of optical communication transmission can be extended. This application form places a demand of higher output power on EDFA.

Fields of application

EDFA has the following fields of application:

(1) EDFA can be employed in the high-capacity and high-speed optical communication system. The application of EDFA is very constructive to deal with the problems of low sensitivity of receivers and short transmission distances owing to a lack of OEO repeater.

(2) EDFA can be utilized in long-haul optical communication system. By utilizing EDFA, we can dramatically lower construction cost by increasing the repeater spacing to reduce the quantity of regenerative repeaters. The long-haul optical communication system mainly includes the land trunk optical transmission system and the submarine optical fiber cable transmission system.

(3) EDFA can be used in the optical fiber subscriber access network system. If the transmission distances are too long, EDFA will function as the line amplifier to compensate for the transmission losses of lines, thus greatly increasing the number of subscribers.

(4) EDFA can be employed in wavelength-division multiplexing (WDM) system, especially dense wavelength-division multiplexing (DWDM) system. Utilization of EDFA in WDM system is able to solve the problems of insertion loss and reduce the influences of chromatic dispersion.

(5) EDFA can be utilized in community antenna television (CATV) system. In CATV system, EDFA functions as the booster amplifier to greatly improve the input power of an optical transmitter. Utilizing EDFA to compensate for the insertion loss of opt

40G Solutions: Duplex Fiber or MPO/MTP Fiber?

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There’s been a lot of talk lately surrounding bidirectional 40 Gb/s duplex applications, or BiDi for short. Currently offered as a solution by Cisco®, BiDi runs over duplex OM3 or OM4 multimode fiber using QSFP modules and wavelength division multiplexing (WDM) technology. It features two 20 Gb/s channels, each transmitting and receiving simultaneously over two wavelengths on a single fiber strand – one direction transmitting in the 832 to 868 nanometer (nm) wavelength range and the other receiving in the 882 to 918 nm wavelength range. Avago Technologies also offers a similar QSFP BiDi transceiver.

Unidirectional 40 Gb/s duplex fiber solutions are available from Arista and Juniper. These differ from the BiDi solution in that they combine four 10 Gb/s channels at different wavelengths – 1270, 1290, 1310, and 1330 nm – over a duplex LC connector using OM3 or OM4 multimode or singlemode fiber. These unidirectional solutions are not interoperable with BiDi solutions because they use different WDM technology and operate within different wavelength ranges.

While some of the transceivers used with these 40 Gb/s duplex fiber solutions are compliant with QSFP specifications and based on the IEEE 40GBASE- LR4 standard, there are currently no existing industry standards for 40 Gb/s duplex fiber applications using multiple wavelengths over multimode fiber – either bidirectional or unidirectional. There are standards-based 40 Gb/s applications over duplex singlemode fiber using WDM technology, but standards-based 40 Gb/s and 100 Gb/s applications over multimode use multi-fiber MPO/MTP connectors and parallel optics (40GBASE-SR4 and 100GBASE-SR4).

40 Gb/s duplex fiber solutions are promoted as offering reduced cost and installation time for quick migration to 40 Gb/s applications due to the ability to reuse the existing duplex 10 Gb/s fiber infrastructure for 40 Gb/s without having to implement MPO/MTP solutions. However, some of the concerns surrounding these non-standards based 40 Gb/s duplex fiber solutions include:

Lack of standards compliance and lack of interoperability with standards-based fiber solutions

Risk of being locked into a sole-sourced/proprietary solution that may have limited future support

BiDi and other 40 Gb/s duplex transceivers require significantly more power than standards-based solutions

Lack of application assurance due to operation outside of the optimal OM3/OM4 wavelength of 850 nm

Limited operating temperature range compared to standards-based solutions

Due to the aforementioned risks and limitations of using non-standards-based 40 Gb/s duplex fiber solutions, we recommends following industry standards and deploying 40GBASE-SR4 for 40 Gb/s applications today. While this standard requires multiple fibers using an MPO/MTP-based solution, it offers complete application assurance and interoperability, as well as overall lower power consumption.

Furthermore, TIA and IEC standards development is currently underway for wideband multimode fiber (WBMMF), which is expected to result in a new fiber type (potentially OM5 or OM4WB) that expands the capacity of multimode fiber over a wider range of wavelengths to support WDM technology. While not set in stone, the wavelengths being discussed within TIA working groups are 850, 880, 910, and 940 nm.

Unlike current 40 Gb/s duplex fiber applications, WBMMF will be a standards-based, interoperable technology that will be backwards compatible with existing OM4 fiber applications. WBMMF is expected to support unidirectional duplex 100 Gb/s fiber links using 25 Gb/s channels on 4 different wavelengths. WBMMF will also support 400 Gb/s using 25 Gb/s channels on 4 different wavelengths over 8 fibers, enabling existing MPO/MTP connectivity to be leveraged for seamless migration from current standards-based 40 Gb/s and 100 Gb/s applications to future standards-based 400 Gb/s applications.

Armoured Cable vs. Unarmoured Cable: What’s The Difference?

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With the rapid development of optical communication, more and more fiber optic cables are increasingly used in different environments. What if under harsh conditions? Then it’s crucial to ensure your cables smooth and reliable operation when transmitting data. This is where armoured cable comes into play. An armoured cable, as its name suggests, is protected against mechanical damage, whereas an unarmoured cable not being protected. What is the difference between them? And why should we choose armoured cable over unarmoured cable? You my find answer in this post.

Amoured Cable Overview

Armoured cable has an extra layer of protection to keep it from being cut or abraded. The armor layer of coax cable is a foil wrap that is ribbed like corrugated metal to allow for flexibility, around the inside and outside of that wrap is a flooding compound to keep moisture from penetrating the cable and causing an impairment. The internal structure of 4 core armoured cable consists of many layers to prevent the cable from damage. The outer jacket provides protection against rodent, abrasion and twist, which is usually made of plastic. And the armoring materials are mainly come from kevlar, steel, and aluminum foils, aiming to protect the armored cable from being stretched during installation.

Difference Between Armoured Cable And Unarmoured Cable

Structure

Many people may think that armoured cable just has metal protection. To be precise, the armoring material doesn’t have to be metal, it can be fiber yarn, glass yarn, polyethylene etc. The only thing that makes armored cable different from unarmored cable is that the former has an additional outer protective layer for optical cable. The 4 core armoured cable tends to be more expensive than unarmored cable, while the armoured cable with steel strip and aluminum is much cheaper than armored fiber cable with Kevlar, which is usually used for special occasions.

Application

Armoured cable is installed in locations exposed to mechanical damage, such as on the outsides of walls, as an alternative to conduit. Armoured cable usually has a small metal ribbon to ensure electrical continuity of the safety ground. (You must run a separate ground wire in flexible conduit too; you can’t depend on the continuity of the conduit.) In HT & LT distribution, 4 core armoured cable is preferred. Inside walls and in other protected locations, less expensive unarmored electrical cable can be installed instead. Unarmoured cable is mainly used for control systems.

Why Should Use Armoured Cable Over Unarmoured Cable?

There are a couple of reasons that armoured cable should be used. The biggest reason is about strength, because armored cable was used more extensively in past decades when cable was simply directly buried under dirt and not used through a conduit. Nowadays most local municipalities require conduits to be trenched in prior to installing network components, thus eliminating the need for unarmored cable in most applications. Secondly, rodents or animals can and will chew through cables so the armor protects the cables from damage by animal or shoveling in direct bury applications. Thirdly, the most uncommon reason it would be used is in an RF environment that has an off air RF signal that is powerful enough to interfere with your network, the armor when grounded can provide another layer of RF protection.

Conclusion

Armoured cable can be regarded as a kind of strengthened cable, which is harder and stronger than standard optical cable. With an unparalleled protection against physical damage without sacrificing flexibility or functionality within fiber networks, 4 core armored cable is a perfect addition to any fiber network in hazardous environments.

Understanding Armored Fiber Patch Cable

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With the development of telecommunication, demands for fiber patch cables are increasing all over the world. However, it is known to all that cables under harsh environment must be in need of better protection. Luckily, the advent of armored fiber patch cable efficiently solves the problem. As the name indicates, this type of optical cable is wrapped in a protective armor to prevent optical cables from animal bite, moisture, corrosion and other damage. Therefore, using armored fiber patch cables will greatly reduce the cost of unnecessary cable loss. This article will give you a basic introduction about the structure, types and advantages of armored optical cable.

Structure of Armored Fiber Patch Cables

Armored fiber optic cable has some basic layers. The first layer is the outer jacket made of plastic materials. It can protect the cable from the destroy of solvent and abrasion. The second layer under outer jacket is the strength member made of armored materials, such as aluminum foil, steel and kevlar. These materials are difficult to cut, bite and burn which are great protections for the optical cable. Next is the inner jacket of fiber made of protective and flame-retardant materials to support the internal optical fibers.

Types of Armored Fiber Optic Cable

Armored fiber patch cables can be divided into indoor armored optical cable and outdoor armored optical cable according to the premises.

Indoor Armored Optical Cable

This kind of optical cable includes double and single indoor armored fiber patch cables. The double armored cable has the stainless steel wire woven and stainless steel tube. On the contrary, the single armored cable does not contain the stainless steel components. Most of the indoor armored cables are deployed for building wiring applications. You may find them in walls, between floors, in plenum air handling ducts and under data center floors, etc.

Outdoor Armored Optical Cable

There are light armored and heavy armored optical cable used for outdoor applications. The light armored cable has the protective plastic jacket with the same durability and longevity of a stainless steel cable, but its weight is much lighter. The heavy armored cable is wrapped in a wire circle which can be applied for riverbed and ocean floor.

Advantages of Armored Fiber Optic Cable

There are numerous advantages of armored fiber optic cable. The flexibility and durability of armored cable are excellent which makes it the right choice for industrial purposes. Moreover, the armor materials protect the cable from damage caused by animal, human or harsh environment, thus it can be applied to places where ordinary cables can not. The armored cable can also undergo heat and high pressure of extreme conditions. Using the armored optical cable not only ensures the high speed data transmission, but also extends the life span of cables.

Conclusion

When fiber optic cables are needed for terrible conditions, a strong protection for the cable is very necessary. Therefore, to secure the data communication, armored fiber optic cable is a good solution to make the cable free from different damages. But when you operate the armored fiber patch cables, you must be careful of the freshly cut edges which are very sharp to cope with. And the budget of your project should also be taken into consideration as armored cables are generally more expensive than the common ones.

Applications for Outside Plant Fiber Optic Cables

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Inside plant refers to the cabling running inside a building. Similarly, outside plant is the cabling

running outdoors. Outside plant cables are thicker because of more durable insulation jackets. As for

fiber optic communication, there are many types of outside plant fiber optic cables. Some have extra

protections to prevent corrosion and other elemental interference. Outside plant fiber optics are

widely used in telephone networks, CATV, metropolitan networks, utilities and so on. If you want to

choose the right outside plant fiber optic cable, its applicable environment is an important factor

for consideration. This post will introduce some common outside plant fiber optic cables and typical

outdoor application environments.

Several Types of Outside Plant Fiber Optic Cables

Outdoor Breakout Cable

Outdoor breakout cable is perfect for rugged applications and installations that require increased

performance. It is usually made of several bundled simplex cables wrapped in a common cable jacket.

The fungus, water and UV protections and temperature durability are beneficial to its outside

applications. Its design of individual fiber reinforcement enables the quick termination to connectors

and omits the use of patch panels or boxes. With much less termination work, outdoor breakout cable is

more cost-effective when small fiber counts and short distances are required.

Outdoor Loose Tube Cable

Outdoor loose tube cable has the gel-filled design protecting the cable from moisture environment. The

gel within the loose-tube construction stops the penetration of water and keeps it away from the

fiber. Also, it keeps water from freezing near the fiber at low temperatures which reduces the chance

of stress fractures. Fibers are bundled inside a small plastic tube that can protect fibers from

outside stresses. Outdoor loose tube cable is often used in conduits, strung overhead or buried

directly into the ground.

Outdoor Ribbon Cable

Outdoor ribbon fiber optic cable has high fiber counts and small cable diameter. It contains the most

fibers in the smallest cable. These fibers are laid out in rows as ribbons, and ribbons are laid on

top of each other. Likewise, it also has gel-filled protection to block outside water. Ribbon cable

makes installation much faster and easier since mass fusion splicers can join a ribbon at once.

Outdoor Armored Cable

Outdoor armored cable is a direct buried type that prevents itself from animal bite. The metal

armoring between two jackets effectively prohibits rodent penetration. Outdoor armored cable can be

divided into light armored and heavy armored types. The former has the protective plastic jacket with

the same durability and longevity of a stainless steel cable with a lighter weight. The latter is

wrapped in a wire circle to be applied for underwater regions that near shores and shoals.

Outside Cable Plant Applications

Outside cable plant deployment can be implemented in many environments. Above-ground, underground,

buried and underwater are the typical applications.

Above-ground Cable Plant

Above-ground cable plant can be exposed to extreme temperatures, and to humidity that varies with the

seasons and with daily temperature changes. Cables under such circumstances should be durable to adapt

to extreme weathers and water penetration.

Underground Cable Plant

Underground cable plant usually applies cables in underground structures including the utility holes,

controlled environmental vaults, ducts and so on. The condition in utility holes and ducts sometimes

can be corrosive because of man-made chemicals. Cables with corrosion-proof materials are perfect for

this environment.

Buried Cable Plant

Buried cable plant applies cables directly into the soil. Cables can also be exposed to the same

corrosive environment as underground plant. But animal bite is an additional problem. Cables for this

application should be very tough to endure both chemical corrosion and animal attack.

Underwater Cable Plant

Underwater cable plant are located beneath the surface of water. The water can range from relatively

pure to brackish, or to badly contaminated with industrial effluent. Cables for underwater plant are

extremely rugged, with fibers in the middle of the cable inside stainless steel tubes and the outside

coated with many layers of steel strength members and conductors for powering repeaters.

Conclusion

Unlike indoor cables, outside plant fiber optic cables must be wrapped in different layers to

withstand the severe installation conditions. Choosing the right kind of outdoor cable can save you a

great deal for long-term maintenance. And your project application is an important aspect that will

affect the selection of fiber optic cables.

Have You Chosen the Right Cables Ties?

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You can frequently find racks, frames or panels in the cabling system. They are necessary components for cable management. However, sometimes you may easily forget about a small but helpful tool for cable management – that is cable tie. People’s first impression about cable tie is always a self-locking and colorful plastic strip. They think cables ties are pretty much the same. Seldom have they considered about whether they are choosing the right or not. In fact, cables ties have many different distinctions in construction, material, color, size and some special features. So do you want to know if your selection is right? Don’t worry. The following parts will give the explanation.

Cable ties have to be able to meet the most varied demands these days as they are used in the widest range of operations – from the simple bundling of cables with cable ties to the absolutely specific use of cable ties under extreme conditions. Thus, many factors are taken into consideration during the design of cable ties.

Cable Tie Construction

Cable ties can be classified as either one-piece or two-piece construction. One-piece cable ties typically have a plastic locking device molded into the head of the tie. The locking device ratchets the notched strap to tighten and lock. This design has a lower cost of manufacturing and is used for general applications around home or office. Compared to one-piece cable ties, two-piece cable ties are with higher performance. They consist of a stainless-steel locking device embedded into the head of the tie, and a smooth locking strap. This design offers high tensile strength, and resistance to mechanical and environmental stress for applications that require greater performance than what a general cable tie offers. In addition, the smooth, infinitely adjustable strap also allows for the exact bundled tightness. The head of the two-piece cable tie engages the strap when installed, and permanently locks in place. With a lower profile and smoother cross-section, the uniform cross-section distributes stress across the strap more evenly than with one-piece cable ties. Thus, the two-piece cable ties are more resistant to brittleness and breakage in harsh environments, particularly appropriate for harsh conditions, such as ultraviolet exposure, extreme temperature, and exposure to moisture or chemicals, as well as for applications where retrofitting is not an option.

Cable Tie Material

The material design of different cable ties also needs to consider for different applications, such as occurring indoors or outdoors; the environment’s temperature range; the presence of moisture, chemicals and radiation; flammability issues; and cost. Cable ties are available in a wide range of materials, each with its own specific properties. Among them, the most common type is nylon cable ties. Nylon ties can offer good resistance to weather and ultraviolet rays in lower temperatures. In addition, for applications in harsher environments that require extra durability in the face of heat, chemicals and other corrosive elements, there are stainless-steel cable ties.

Cable Tie Color

The most commonly used cable ties are white and black. But colorful cable ties are also popular with users. These cable ties with rainbow colors are very useful when you are trying to color-code your cables, or just want to match the ties to your equipment. Moreover, you can use different cable ties to mark different cables bunch which is convenient for cable management.

Cable Tie Size

When using cable ties, you should also consider the size and shape. First, be sure to measure the diameter of the cable bundle you’ll be tying and decide the length. In general, to buy cable ties with a little longer length is better. Because no one wants to find out at the last minute that the cable ties are too short to use. In addition to length, width or shape are also important considerations to choose optimal cable ties for your cable bunch.

Cable Tie Special Features

Though the standard-design cable ties can meet most of our requirements, sometimes, we still need something special for special applications. For instance, most cable ties lock permanently, but sometimes, we would prefer to looking for a solution that cable ties can be undone without actual cutting. Then, releasable cable ties have been launched in the market. In a releasable cable tie, the built-in locking tab can actually be disengaged, allowing the tail end of the tie to be pulled free from the head. Releasable cable ties tend to cost a little more than the standard type, but they save money and are more eco-friendly in the long run because you can reuse them over and over instead of just throwing them away. Additionally, for different special applications, there are mounted head cable ties, marker ties, etc.

Conclusion

It is very unprofessional to use random cable ties for your cable management. Knowing the secrets about cable ties can lead you to choose the matching cable ties for your applications. This will greatly reduce the unnecessary problems during actual practice. Actually, no matter cable ties or other assembles, each component of cabling system should not be underestimated. The right selection will greatly increase the efficiency of a cabling system.

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