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The Core And Cladding Of Fiber Optic Cable


Fiber optic cables transmit data through very small cores at the speed of light. Significantly different from copper cables, fiber optic cables offer high bandwidths and low losses, which allow high data-transmission rates over long distances. Light propagates throughout the fiber cables according to the principle of total internal reflection.

There are three common types of fiber optic cables: single-mode, multimode, and graded-index. Each has its advantages and disadvantages. There also are several different designs of fiber optic cables, each made for different applications. In addition, new fiber optic cables with different core and cladding designs have been emerging; these are faster and can carry more modes. While fiber optic cable are used mostly in communication systems, they also have established medical, military, scanning, imaging, and sensing applications. They are also used in optical fiber devices and fiber optic lighting.

Fiber optic cable is a filament of transparent material used to transmit light, as shown in Figure 1.2. Virtually all fiber optic cables share the same fundamental structure. The centre of the cable is referred to as the core. It has a highter refractive index than the cladding, which surrounds the core. The contact surface between the core and the cladding creates an interface surface that guides the light; the difference between the refractive index of the core and cladding is what causes the mirror like interface surface, which guides light along the core. Light bounces through the core from one end to the other according to the principle of total internal reflection, as explained by the laws of light. The cladding is then covered with a protective plastic or PVC jacket. The diameters of the core,cladding, and jacket can vary widely; for a single fiber optic cable can have core, cladding, and jacket diameters of 9, 125, and 250 um, respectively.

Figure 1.3 shows the structure of a typical fiber optic cable. The cores of most fiber optic cables are made from pure glass, while the cladding are made from less pure glass. Glass fiber optic cable has the lowest attenuation over long distances but comes at the highest cost. A pure glass fiber optic cable has a glass cladding. Fiber optic cable cores and claddings may be made from plastic, which is not as clear as glass but is more flexible and easier to handle. Compared with other fiber cables, Plastic Optical Fiber Cable is limited in power loss and bandwidth. However, they are more affordable, easy to use, and attractive in applications where high bandwidth or low loss is not a concern. A few glass fiber cable cores are clad with plastic. Their performance, though not as good as all-glass fiber cables, is quite respectable.

fiber optic cable

The jacket is made from polymmer (PVC, plastic, etc.) to protect the core and the cladding from mechanical damage. The jackets has several major attributes, including bending ability, abrasion resistance, static fatigue protection, toughness, moisture resistance, and the ability to be stripped. Fiber optic cable jackets are made in different colours for colour-coding identification. Some optical fibers are coated with a copper-based alloy that allows operation at up to 700 and 500℃ for short and long periods, respectively.

Fiberstore is a leading supplier of Bulk Fiber Optic Cable and components into the umbilical and towed array products for the oil & gas sector. The key technology for these products is Fiberstore’s patented stainless steel fiber optic tube technology which packages the optical fiber in the best possible way resulting in a robust, compact product that is suitable for the high pressure of the subsea environment. Fiberstore will customize the design to meet your needs to include different fiber counts, fiber types, metal types, tube sizes, belting materials, armor type, armor size, armor count, encapsulation types, color, print, packaging and length.

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More Characteristics of Fiber Optic Cable

When light from a source is sent through a fiber-optic cable, the ligth wave both bounces around inside the cable and passes through the cable to the outlet protective jacket. When a light signal inside the cable bounces off the cable wall and back into the cable, this is called reflection. When a light signal passes from the core of the cable into the surrounding material, this is called refraction. Figure 3-9 demonstrates the differece between reflection and refraction.

Light can be transmitted through a fiber-optic cable using two basic techniques. The first technique, called single-mode transmission, requires the use of a very thin fiber-optic cable and a very focused light source, such as a laser. When a laser is fired down a narrow fiber, the light follows a tight beam, and so there is less tendency for the light wave to reflect or refract. Thus, this technique allows for a very fast signal with little signal degradation (and thus less noise) over long distances. Because lasers are used as the light source, single-mode transmission is a more expensive techique than the second fiber-optic cable signaling techique. Any application that involves a large amount of data transmitted at high speeds is a candidate for single-mode transmission.

The second signaling technique, called multimode transmission, uses a slightly thicker fiber cable and an unfocused light source, such as an LED. Because the light source is unfocused, the light wave experiences more refraction and reflection (i.e, noise) as it propagates through the wire. This noise results in signals that cannot travel as far or as fast as the signals generated with the single-mode technique. Correspondingly, multimode transmission is less expensive than single-mode transmission. Local area networks that employ fiber-optic cables often use multimode transmissions.

Single-mode and multimode transmission techniuqes use fiber-optic cable with different characteristics. The core of single-mode fiber-optic cable is 8.3 microns wide, and the material surrounding the fiber – the cladding – is 125 microns wide. Hence, single-mode fiber optic cable is labeled 8.3/15 cable. The core of multimode fiber optic cable is most commonly 62.5 microns wide, and the cladding is 125 microns. Multimode fiber optic cable is labeled 62.5/125 cable. Othe sizes of multimode fiber optic cable include 50/125 and 100/140 microns.

Bulk fiber optic cable comes in lots of types, depending on where it will be installed. Where to buy fiber optic cable? As the best OEM fiber optic cable manufacturer, Fiberstore provides a wide range of quality optical fiber cables with detailed specifications displayed for your convenient selecting. Per foot price of each fiber cable is flexible depending on the quantities of your order, making your cost of large order unexpected lower. Customers can also have the flexibility to custom the cable plant to best fit their needs. Only fiber cable that meets or exceeds industry standards is used to ensure quality products with best-in-class performance. Fiberstore offers an extensive line of off the shelf bulk fiber optic cable to address your fiber installation needs. We stock 62.5/125, 50/125, and 9/125 bulk fiber optic cable in simplex, duplex (zip cord), breakout, and distribution styles.

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Three Common Types Of Fiber Optic Cables

There are, three common types of fiber optic cables, as listed below. The suitability of each type for a particular application depends on the fiber optic cable’s characteristics.

The single-mode step-index fiber cable, sometimes called a single-mode fiber cable, is shown in Figure 1.5(a). The single and multimode step-index fiber cables are the simpplest types. Single-mode fiber cables have extremely small core diameters, ranging from 5 to 9.5 um. The core is surrounded by a standard cladding diameter of 125 um. The jacket is applied on the cladding to provide mechanical protection, as shown in Figure 1.3. Jackets are made of one type of polymer in different colours for colour-coding purposes. Single-mode fibers have the potential to carry signals for long distances with low loss, and are mainly used in communication systems. The number of modes that propagate in a single-mode fiber depends on the wavelength of light carried. The number of modes will be given in Equation (1.9). A wavelength of 980nm results in multimode operation. As the wavelength is increased, the fiber carries fewer and fewer modes until only one mode remains. Single-mode operation begins when the wavelength approaches the core diameter. At 1310 nm, for example, the fiber cable permits only one mode. It then operates as a single-mode fiber cable.

singlemode fiber

The multimode step-index fiber cable, sometimes called a multimode fiber cable. Multimode fiber cables have bigger diameters that their single-mode counerparts, with core diameters ranging from 100 to 970 um. They are available as glass fibers (a glass core and glass cladding), plastic-clas silica (a glass core and plastic cladding), and plastic fibers (a plastic core and cladding). They are also the widest ranging, although not the most efficient in long distances, and they experience higher losses than the single-mode fiber cables. Multimode fiber cables have the potential to carry signals for moderate and long distance with low loss (when optical amplifiers are used to boost the signals to the required power). Plastic fiber optic cable is available in Fiberstore,  it is an optical fiber made out of plastic rather than traditional glass. It offers additional durability for uses in data communications, as well as decoration, illumination and industrial application. FiberStore provides both simplex and duplex plastic optical fibers.

Since light rays bounded through a fiber cable reflect at different angles for different ray pathc, the path lengths of different modes will aslo be different. Thus, different rays take a shorter or longer time to travel the lenth of the fiber cable. The ray that goes straight down the centre of the core without reflecting arrives at the other end faster. Other rays take slightly longer and thus arrive later. Accoringly, light rays entering a fiber at the same time will exit at the other end at different times. In time, the light will spread out because of the different modes. This is called modal dispersion. Dispersion describes the spreading of light rays by various mechanisms. Modal dispersion is that type of dispersion that results from the varying modal patch lengths in the fiber cable.

Multimode graded-index fiber are sometimes called graded-index fiber cables (GRIN). Graded-index and multimode fiber cables have similar diameters. Common graded-index fibers have core diameters of 50,62.5, or 85 um, with a cladding diameter of 125 um. The core consist of numerous concentric layers of glass, somewhat like the annular rings of a tree or a piece of onion. Each successive layer expanding outward from the central axis of the core until the inner diameter of the cladding has a lower index of refrection. Light travels faster in an optical material that has a lower index of refraction. Thus, the further the light is from the centre axis, the greater its speed. This type of fiber optic cable is popular in applications that require a wide range of wavelenths, in particular telecommunication, scanning, imaging, and data processing stystems. In particular telecommunication,  Multimode OM4 fiber optic cable is used in any data center looking for high speeds of 10G or even 40G or 100G. OM4 multimode fiber are ideal for using in many applications such as Local Area Networks (LAN) backbones, Storage Area Networks (SAN), Data Centers and Central Offices.

multimode fiber

Fiberstore provides a wide range of bulk fiber optic cable with detailed specifications displayed for your convenient selecting. Per foot price of each fiber cable is flexible depending on the quantities of your order, making your cost of large order unexpected lower. Customers can also have the flexibility to custom the cable plant to best fit their needs.

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How To Improve The Reliable And Stable Operation Of The Optical Fiber Cable

The fiber optical cable is a certain amount of fiber cable core, according to certain outsourcing jacket, and some coated outer sheath to achieve a communication line of the optical signal transmission. The fiber optic cable is today’s information society various information network transfer tool. If the “Internet” is referred to as the “information superhighway”, then the fiber optic cable network is the cornerstone of the information highway – cable network is the physical routing of the Internet. Once a cable destruction and blocking, the direction of the “information superhighway” is destroyed. Through the optical transmission of information, in addition to the usual telephone, telex, fax outside, a large number of transmission moment of television signals, bank transfer, the stock market can not be interrupted. , Cable plays an important role in today’s information society, once the cable is damaged, easy to make the communication to transmit information is not working properly, affecting work and life.

So, in today’s information society, how to improve the reliable and stable operation of the ordinary optical fiber cable is an important topic that we can not ignore.

The first point, the path of scientific and rational choice. Ordinary Aerial Cable is running the main members of the power of optical networking. To make the cable safe and stable operation, we must first choose a suitable path after construction but also maintenance personnel regularly check and maintenance in order to ensure the stable operation of the fiber optic cable in the future. The path of the fiber optic cable along the highway should try to choose, Village Road side toward the outside but also consider other environmental factors.

The second point, the loss of the fiber optic cable and its solutions. The stability and reliability of the optical fiber and transmission loss characteristics is to determine one of the most important factor of the optical fiber transmission distance optical fiber transmission loss causes are many, in the construction and maintenance of optical fiber communication network, the most noteworthy is the fiber transmission loss caused and how to reduce these losses. Transmission loss is mainly caused in the use of fiber splice loss (inherent in the fiber splicing losses and activities splice loss) and non-splice loss (caused by the loss of bending loss and other construction factors and application environment) categories.

Cable design and planning, rational distribution, construction experience needs to continue to explore and accumulate further improve the fiber optic cable construction program. Eliminating defects by means of fiber-optic cables run, constantly sum up the problems found in the running, can improve the quality of optical transmission, to extend the service life of the fiber optic cable, to adapt to the needs of the system communications and development and construction.From FiberStore,we provide some types of bulk fiber optic cable,including Indoor Cables, Outdoor Cables, FTTH Cables, Armored Cables, LSZH Cables and some special cables. They are various at Aerial Cables, Building Cables, Direct buried cables, Duct Cables, Underwater/Submarine Cable. If you have any questions with fiber optic cable,welcome to contact us Sales@fs.com .