Understanding Singlemode and Multimode Fiber Optic Cables

Fiber optic cables are generally divided into two types: single mode and multi-mode. Understanding characteristics of each fiber types help understand the applications for which they are used. Earlier in 1970, fiber optic cables are researched to have the capabilities of carrying 65,000 times more information then just regular copper wire, through with information carried by a pattern of light waves that could be detected at a distance of even 1000 miles away.

Real life uses of fiber optics
There are two basic types of fiber optic cables: multi-mode and single mode fiber. Multimode fiber is best designed for short transmission distances, and is suitable for use in LAN systems and video surveillance. Single-mode fiber is best designed for longer transmission distances, making it suitable for long-distance telephony and multichannel television broadcast systems. Fiber optics is very important in communications, because it can be used to transmit information very efficiently. Fiber optics also have visual users. Fiber optics is used in medicine to look inside the body. By using optical fiber cables, doctors can examine organs and diagnose illness without surgury or X-rays. Optical fibers can also deliver laser light to specific points in side the body to help surgons with delicate surgery. A local radia station uses fiber optical cables instead of FM waves.

Multimode and Singlemode Fiber
Multimode fiber is the first to be manufactured and commercialized, simply refers to the fact that numerous modes or light rays are carried simultaneously through the waveguide. Modes result from the fact that light will only propagate in the fiber core at discrete angle within the cone of acceptance. This fiber type has a much large core diameter, compared to single-mode fiber, allowing for the larger number of modes, and multimode fiber is easier to couple than single-mode optical fiber. Multimode fiber may be categorized as step-index or graded-index fiber. Multimode Step-index Fiber core’s index of refraction is higher than the cladding’s index of refraction, the light that enters at less than the critical angle is guided along the fiber. Multimode graded-index fiber core’s refractive index is parabolic, being higher at the center. They follow a serpentine path being gradually bent back toward the center by the continuously declining refractive index.

Single-mode fiber allows for a higher capacity to transmit information because it can retain the fidelity of each light pulse over longer distances, and it exhibits no dispersion caused by multiple modes. Single-mode fiber also enjoys lower fiber attenuation than multimode fiber. Thus, more information can be transmitted per unit of time. Like multimode fiber, early single-mode fiber was generally characterized as step-index fiber meaning the refractive index of the fiber core is a step above that of the cladding rather than graduated as it is in graded-index fiber. Modern single-mode fibers have evolved into more complex designs such as matched clad, depressed clad and other exotic structures.

A interesting fact is that an optical fiber cable is less than 1/2 inch in diameter, which could carry more than 40,000 telephone conversations at once. Today more than 80% of the worlds long-distance traffic is carried over optical fiber cables.Additional important variety of multimode and single mode fiber includes polarization-maintaining, Low smoke zero halogen, armored fiber.

This article is source from fibre optic cable manufacturers.

FiberStore Introduced the New 10G OM3 Indoor Outdoor Plenum Distribution Cables

FiberStore introduces the new 10G OM3 Indoor/Outdoor plenum distribution cables, which are ideal for networking in ducts, risers, and air handing spaces where small size, lightweight, and versatile installation capacity are required.

FiberStore has updated its line of OM3 OM4 10G fiber cables with the new OM3 Indoor/Outdoor Plenum distribution cables. The new simplex to 24 strand multimode 50/125 10G OM3 indoor/outdoor plenum distribution cables supports installation where small size, lightweight, and versatile installation capability are required for ducts, risers, and air handing spaces.

This distribution plenum rate fiber optic cable is composed of 2 to 24 colored tight buffers, plus the high specific strength-to-weight radio and compact cable design for limited conduit space and tight bends in long cable pulls, allowing designers, installers and operators of enterprise networks to use multimode optical fiber in a package that is easier to handle and install.

Based on 900 μm tight buffered designs, FiberStore’s Indoor/Outdoor Plenum cable eliminates the need for costly and time-consuming installation of fanout kits or pigtail splices since the connectors terminate directly to the fiber. The outer jacket is moisture, fungus and UV-resistant, making FiberStore Indoor/Outdoor Plenum Distribution Cable reliable for both outdoor and underground buried-duct applications.

“With a strong focus on engineering and design, FiberStore continually works on improving our solutions by listening to our customer base. The new design of the indoor/outdoor plenum-rated cable was a direct result of customer feedback in order to meet the need for networking in areas with limited space or tight bends. ” explained Thomas Cole, commercial manager for enterpriser cables at FiberStore. “Our updated family of Indoor/Outdoor plenum-rated cables provides a sound building block for those networks.”

The new Indoor/Outdoor Plenum distribution cable is suitable for spaces requiring plenum, riser, general purpose and outside plant UL flame ratings. Available in single-mode and multimode, including laser-optimized 50 μm OM3, cables within the family are also available with options up to 24 fibers and customized fiber or sheath colors, sheath material and cables length.

About FiberStore
FiberStore is one of the industry fast growing fiber optic cable suppliers offering industrial-leading products and services to electric utility, broadband, communications, OEM, enterprise, wireless and transit rail markets as well as the emerging markets of oil and gas, mining, nuclear, avionics, medical, renewable and intelligent grid. The company’s diverse products portfolio includes fiber optic cable, transmission and substation accessories, outside plant equipment, connectors, fusion splicer, test equipment and training. Since its establishment in 2001, FiberStore is proud to offer engineering expertise, exceptional products and reliable service that help customers improve their critical and electrical infrastructure. For more information, visit www.fiberstore.com

Extending the Life of Fiber Optic Cables

How to ensure the service life of Fiber optic cable more than 20 years
In the long-distance optical communication systems, Fiber Optic Transmission characteristics should be the long-term stability, especially long distance buried Fiber Optic Cable and submarine cable systems, long life put forward higher requirements for fiber optic cable. Generally land cable service life and hope to have more than 20 years of safe use, while the submarine cable is required to improve its service life to 25 years, and its mean time between failure of 10 years required. Therefore, how to enxtend the life of the cable, how to properly use the fiber optic cable, is an important technical issues people care about, from the aspects of the structure of the cable under the talk about how to extend the service life of the cable.
There are three factors affect the life of Optic Fiber Cable
Optical fiber is one of the most important composition of the material in the fiber optic cable, to improve the service life of the cable, the most fundamental is to improve the service life of optical fiber.
The main factors for influencing service life of optical fiber are:
1. Fiber surface microcracks existence and expansion;
2. Atmosphere of water vapor molecules on the surface of the fiber and etching;
3. Unreasonable cable laying stress left over from long-term effects, etc.
For these reasons, making quartz glass-based optical fiber mechanical strength decreased, attenuation gradually increased, finally to a fiber break, the life of the cable termination. Because of the fiber surface there will always be a micro-cracks, occurring in the atmosphere slowcrack growth, the crack continues to expand, the gradual degration of the mechanical strength of the fiber. For example, a 125μm diameter quartz fiber, after three years of slow change in the future, the tensile strength of the fiber from 180kpsi (equivalent to 1530g tensile strength), dropped 60kpsi (equivalent to 510g tensile strength). Such slow changes caused by the fiber mechanical strength reduction principle is: When the fiber surface micro-cracks (or defects), under the external stress, the fracture does not immediately, only when the stress reaches the critical value of crack, the fiber will break. the silica fibers exposed to a constant stress less than the critical value, the surface cracks will occur slowly expanded, the depth of the crack fracture critical value, which is the process of degradation of the mechanical strength of the fiber. Quartz optical fiber mechanical strength degradation is due to the stress of water and atmospheric environment under the joint action of erosion and water vapor molecules.
The method for prolonging the service life of the optical fiber
When the fiber in a vacuum environment, since there is no water molecules, so that the stress does not occur erosion, the fatigue parameters of N is the maximum value, the fiber also has the highest strength, when the strength is the strength of the inert fibers, called Si. Fibers in the environment of use and it has a service life of ts and the stress σ inert fibers have the following relationship between the intensity of Si:lgts=-nlgσ+lgB+(n-2)lgSi the latter two are the above formula constant, when subjected to constant stress σ, the service life of the fiber and fiber fatigue ts only value the parameter N. The larger the value of N, the optical fiber is the longer life of ts.
Therefore, improving the service life of the optical fiber in two ways:
First, when the fatigue parameter n is fixed, the service life of the optical fiber is exposed only to ts stress σ, and therefore, reduce the stress exerted onto the optical fiber is to improve the service life of a method of optical fiber. When people make optical fiber on fiber surface to form a compressive stress to fight on the tensile stress, decrease the tensile stress at a level that is as small as possible, thereby generating a compressive stress on the cladding layer technology to manufacture optical fibers.
If set to withstand stress fiber σa, life t1, when the fiber cladding has a compressive stress σR, the fiber’s life t2: t2 = t1 [(σa-σR) / σa]-n
Of which, (σa-σR) for the fiber to withstand real net stress. It is suggested that: a compressive stress cladding optical fiber than the life longer. In recent years, some people do quartz GeO2-doped fiber surface compression layer, it was done with a quartz optical fiber doped TiO2 cladding tensile strength of the fiber itself from 50kpsi increased to 130kpsi (considerable tensile strength increased from 430g to 1100g), also the optical fiber static Fatigue from n= 20~25 raised to n = 130.
The second, to improve the static fatigue parameter n optical fibers to improve the service life of the fiber. Therefore, people in the manufacture of optical fibers, quartz fibers themselves try to cut off the atmosphere, so that from atmospheric environment, the possible value of n material parameters from the environment into the parameters of fiber material itself, can make the value of n becomes large, resulting in the surface of the fiber of the “seal coating technology”.
Over the past decade, the use of “seal coating technology” to produce optical fiber made tremendous progress. Extended by a metal coating material to the metal oxides, inorganic carbides, inorganic nitrides, carbides, oxides of nitrogen and CVD-deposited amorphous carbon. Coating layer structure of the metal coating layer by a single seal coating layer to the development of the organic coating layer is combined with a composite coating layer structure, the fiber value of more practical application, the fiber optical properties, mechanical properties and fatigue resistance are improved.
For example:
1. metal coated optical fiber: aluminum coated optical fiber can withstand 1Gpa (150kpsi) stress test submerged in water, at a temperature of 350℃ to use, life expectancy at 10 years.
2. Metal oxides and other inorganic fibers coated: with C4H10 and deposited on the fiber surface SiH4 Si0.21O0.22C0.77 sealing coating layer was coated with the organic layer, the n-value of the fiber to 256.
3. As sealed with a coating layer of boron nitride fibers: 200kpsi can withstand the tension, n value can be increased to 100 or more. Another example is coated with a sealing TIC 400 ~ 500kpsi fiber has a strength of 100 ℃ water resistant.
4. Seal amorphous carbon coated optical fiber: the inorganic coating material, the amorphous carbon coating layer is not only the fiber optical properties and mechanical strength of the effect is little damage, and showed excellent water resistance properties and resistance to hydrogen. This technology has come of industrial production. The typical tensile strength of the fibers has reached 500-600kpsi, dynamic n-value of 350 to 1000. After 25 years at room temperature, the carbon fiber penetration seal coating hydrogen is only an ordinary fiber 1/10000; in fiber optic cable, these fibers may allow hydrogen pressure is 100 times higher than normal fiber. With this optical fiber cable can be suitably reduced to conditions or under the conditions of higher temperatures.
Using fiber surface growth “stress cladding layer” and “sealing coating technique”, the life of the optical fiber can be introduced following formula: t2/t1 = 19.36 × 10IRσa7 formula, σa is the applied stress or stress. Σa which can be calculated with the relationship t2/t1. Such fibers life of up to 40 years and could be used for submarine cables and military communications.
Some other studies also shown that manufacturing optical fiber by using germanium (GeO2) and fluorine (F) as a doping agent, and without phosphorus (P2O5) as a dopant, because phosphorus “water (H2O)” good, the fiber susceptible to moisture, causing the core internal P-OH bond absorption attenuation increases, the fiber slowly changing. So long service life of optical fiber to eliminate with phosphorus mixed materials.
In the manufacturing process, pay attention to moisture waterproof cable to reduce residual stresses. The first is the cable core design, be sure to use loose structure to prevent leaving residual stress, Stranded cable when I want to select a reasonable length of fiber, but also can reduce the tensile stress effect; in the cable core is filled with petroleum gel, purpose is to proof, waterproof, anti-hydrogen-containing compound (contaminated liquid) etching; using plastic coated steel, aluminum also to moisture, increased cable resistance to lateral pressure, tensile capacity; some factories in the cable core intervals one meter to add a hot melt adhesive water blocking layer to prevent the cable core longitudinal water penetration; selection of small linear expansion coefficient of the material for the strength of the cable core element, the purpose is to protect the fiber, eliminating the external tension. Finally it should also be noted that each of the manufactured fiber raw material itself must have more than 30 years of life, must have a high stability of the physical properties and chemical properties. Only by strictly controlling the quality of the manufacturing process of the road, it can extend the life of the cable.

Fiber Optic Cables For Harsh Environment Applications

Fiber based systems offer apparent advantages over electrical methods in large plants and factories where the harsh environment threatens data reliability and security. Unlike copper cable, fiber optic cabling is resistant to electromagnetic interference (EMI), making it an ideal option for harsh environments involving high voltages or machinery with variable frequency drives, is a safe alternative to traditional wiring.

As you know, fiber optic cable consists of three parts: the core, the cladding, and the coating. The core transmits the light and has a high refractive index. The cladding contains the light within the core because its lower refractive index causes all the light rays to reflect back into the core. This “total internal reflection” or “fiber-optic effect” is the technology’s underlying principle. The coating, usually an acrylate polymer, protects the core/cladding assembly.

Optical fiber is typically made from high-purity silica glass. Plastic fiber of varying configurations is also available. But the attenuation of light energy can approach one thousand times that of glass fiber. The length and integrity of the transmission path and the core/cladding arrangement affect the bandwidth, or the frequency range that the optical fiber transmits. Fiber bandwidth is expressed in megahertz-kilometers (MHz-km).

Depending on the application, the distance involved, and the location, several types of cable configurations and connector types are available. Optical fiber is fragile and must be protected, mostly from mechanical stresses such as bending, crushing, thermal effects, and pulling during installation.

Tight Tube And Loose Tube Cable

A tight-tube (or tight-buffer) design has a PVC coating, which tightly bonds to the fiber, limiting movement. This cable type can have strength members, which you pull through conduit and cable trays. This design, however, has low crush resistance and is susceptible to deformation due to thermal expansion; thus, it is recommended for indoor use only.

A loose-tube design gives a fiber free movement. Each component of the Loose Tube Cables (the sheath or outer coating, the strength member, and the buffer tubes that carry the fibers) has different thermal characteristics. By allowing the fibers and the components surrounding them free movement, deformation is avoided.

Loose-tube construction has much better crush resistance than tight tube because of the buffer-tube protection of the fibers. Loose-tube cables have a strength member, which is used as the pulling member for conduit installation. Loose-tube cables are usually filled with a gel, which surrounds the fibers and increases protection from water. This also improves crash resistance because of the gel’s cushioning effect. You mostly use this cable type for outdoor applications, but you can also use it in harsh industrial environments. A drawback to this type of cable is the difficulty in handling individual fibers. The fiber coating does not have to be as thick as in tight-tube construction; thus, attaching connectors is difficult.

Remember that tight-tube construction does not allow for free movement and provides low protection against mechanical stress. It does, however, have a thick coating for ease of handling. Loose-tube construction, on the other hand, allows free movement and provides a good degree of protection.

Breakout Cable

Breakout cables are a hybrid solution. In a breakout cable, each fiber is treated as a separate unit, complete with a sheath and strength member. This design eliminates the need for a breakout kit, because the sheath lets you attach connectors easily.

Breakout Cable Fiber let fiber subunits move freely, and they protect each fiber by virtue of their thicker coating/strength member arrangement. Each fiber subunit is configured as a tight tube. Breakout cables also come equipped with a separate strength member just like the loose-tube design.

FiberStore harsh environment Fiber Cables is designed and manufactured with specialized components which provide improved performance and protection against damage, breakage, and performance limiting conditions that often exist in harsh environment applications. FiberStore has the resources, expertise, and experience to design, develop, manufacture, install, and maintain a product ideally suited for your exact application.