Fiber

Some 10 billion digital bits can be transmitted per second along an optical fiber link in a commercial network, enough to carry tens of thousands of telephone calls. Hair-thin fibers consist of two concentric layers of high-purity silica glass the core and the cladding, which are enclosed by a protective sheath. Light rays modulated into digital pulses with a laser or a light-emitting diode move along the core without penetrating the cladding.

The light stays confined to the core because the cladding has a lower refractive index—a measure of its ability to bend light. Refinements in optical fibers, along with the development of new lasers and diodes, may one day allow commercial fiber-optic networks to carry trillions of bits of data per second.

Siemens wins two orders from South Africa's Neotel, Juniper to supply core network routers

MARCH 16, 2007 ? The South African Second National Operator (SNO) Neotel, Johannesburg, has commissioned Siemens Networks (search for Siemens) to build a nationwide IP core network and a DWDM transport network. Siemens has partnered with Juniper Networks (search for Juniper Networks) to deploy the IP network. Neotel's investment in high-performance network technologies is targeted at offering residential and business customers high-quality, low-cost multimedia communications services.

Siemens Networks in South Africa (Siemens Telecommunications) will build the cutting-edge IP core network for Neotel. To ensure high end-to-end quality, Neotel is also investing in a DWDM transport network, enabling transfer rates of 40 Gbits per wavelength, with each fiber-optic cable providing 80 wavelengths. Juniper will supply its M- and T-series IP routers, including the T640 core router, to be integrated in the core network.

Apart from this network partnership, Neotel and Siemens Telecommunications have also launched a joint education initiative in South Africa, intended to create a highly qualified workforce that will boost modernization of the telecommunications sector in South Africa. Siemens founded its own Telecommunications Training Institute in Johannesburg 6 years ago, turning out more than 300 graduates with a degree that qualifies them to work in the telecommunications sector.

Multimode cable

is made of of glass fibers, with a common diameters in the 50-to-100 micron range for the light carry component (the most common size is 62.5). POF is a newer plastic-based cable which promises performance similar to glass cable on very short runs, but at a lower cost.

Multimode fiber gives you high bandwidth at high speeds over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fiber core diameters are 50, 62.5, and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 meters), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission.

The use of fiber-optics was generally not available until 1970 when Corning Glass Works was able to produce a fiber with a loss of 20 dB/km. It was recognized that optical fiber would be feasible for telecommunication transmission only if glass could be developed so pure that attenuation would be 20dB/km or less. That is, 1% of the light would remain after traveling 1 km. Today's optical fiber attenuation ranges from 0.5dB/km to 1000dB/km depending on the optical fiber used. Attenuation limits are based on intended application.

The applications of optical fiber communications have increased at a rapid rate, since the first commercial installation of a fiber-optic system in 1977. Telephone companies began early on, replacing their old copper wire systems with optical fiber lines. Today's telephone companies use optical fiber throughout their system as the backbone architecture and as the long-distance connection between city phone systems.

Cable television companies have also began integrating fiber-optics into their cable systems. The trunk lines that connect central offices have generally been replaced with optical fiber. Some providers have begun experimenting with fiber to the curb using a fiber/coaxial hybrid. Such a hybrid allows for the integration of fiber and coaxial at a neighborhood location. This location, called a node, would provide the optical receiver that converts the light impulses back to electronic signals. The signals could then be fed to individual homes via coaxial cable.

Local Area Networks (LAN) is a collective group of computers, or computer systems, connected to each other allowing for shared program software or data bases. Colleges, universities, office buildings, and industrial plants, just to name a few, all make use of optical fiber within their LAN systems.

Power companies are an emerging group that have begun to utilize fiber-optics in their communication systems. Most power utilities already have fiber-optic communication systems in use for monitoring their power grid systems.

Single Mode cable

... is a single stand of glass fiber with a diameter of 8.3 to 10 microns that has one mode of transmission. Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber.

Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type.

Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm.

1-NEWS: Fujikura offers bend-resistant fiber for FTTH

MARCH 7 2007 -- Fujikura Europe Ltd. (search for Fujikura Europe) has launched a new bend-resistant fiber for the FTTH market. FutureGuide SR7.5 has a minimum bend radius of 7.5 mm, making it one of the most flexible fibers in the world, the company asserts.

Available in a MageTsuyo SR7.5 patch cord, Fujikura Europe says the fiber is not only flexible but highly durable. When twisted or bent the fiber returns to its original condition without any deformation or marking on the sheath.

With the ability to be manipulated in the same way as electrical or telephone cable, the fiber can be used to deliver high-bandwidth communications directly into the home or office environment. The qualities of this fiber have also allowed Fujikura to develop a number of new, smaller, more space-efficient closures, including connector plugs and sockets.

"Optical fiber offers the bandwidth required to bring applications such as IPTV and online gaming into people's homes," said Grant Ogilvie at Fujikura Europe Ltd. "Fujikura has taken its experience of fiber roll-out in Japan -- the most advanced FTTx market in the world -- and has developed a product that can stand up to the rigors of the home and office. European incumbent operators are now looking at FTTx as a means of deploying the services their customers are demanding; Fujikura's fiber offers them the flexibility and durability to bring optical fiber, not only to the curb, but right into customers' living rooms."

The MageTsuyo SR7.5 patch cord has an outer diameter of 4 mm. The cord can withstand tension of up to 68.5 N and lateral pressure of up to 1200 N/25 mm. The SR7.5 follows the launch last year of the SR15, which has been deployed extensively in patch cords, indoor cable and drop cables.

2. Types of fiber-optic cable

There are three types of fiber optic cable commonly used: single mode, multimode and plastic optical fiber (POF).

Transparent glass or plastic fibers which allow light to be guided from one end to the other with minimal loss.

Fiber optic cable functions as a "light guide," guiding the light introduced at one end of the cable through to the other end. The light source can either be a light-emitting diode (LED)) or a laser.

The light source is pulsed on and off, and a light-sensitive receiver on the other end of the cable converts the pulses back into the digital ones and zeros of the original signal.

Even laser light shining through a fiber optic cable is subject to loss of strength, primarily through dispersion and scattering of the light, within the cable itself. The faster the laser fluctuates, the greater the risk of dispersion. Light strengtheners, called repeaters, may be necessary to refresh the signal in certain applications.

While fiber optic cable itself has become cheaper over time - a equivalent length of copper cable cost less per foot but not in capacity. Fiber optic cable connectors and the equipment needed to install them are still more expensive than their copper counterparts.

BRIEF OVER VIEW OF FIBER OPTIC CABLE ADVANTAGES OVER COPPER:

• SPEED: Fiber optic networks operate at high speeds - up into the gigabits
• BANDWIDTH: large carrying capacity
• DISTANCE: Signals can be transmitted further without needing to be "refreshed" or strengthened.
• RESISTANCE: Greater resistance to electromagnetic noise such as radios,motors or other nearby cables.
• MAINTENANCE: Fiber optic cables costs much less to maintain.

In recent years it has become apparent that fiber-optics are steadily replacing copper wire as an appropriate means of communication signal transmission. They span the long distances between local phone systems as well as providing the backbone for many network systems. Other system users include cable television services, university campuses, office buildings, industrial plants, and electric utility companies.

A fiber-optic system is similar to the copper wire system that fiber-optics is replacing. The difference is that fiber-optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a fiber-optic chain will give a better understanding of how the system works in conjunction with wire based systems.

At one end of the system is a transmitter. This is the place of origin for information coming on to fiber-optic lines. The transmitter accepts coded electronic pulse information coming from copper wire. It then processes and translates that information into equivalently coded light pulses. A light-emitting diode (LED) or an injection-laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funneled into the fiber-optic medium where they transmit themselves down the line.

Think of a fiber cable in terms of very long cardboard roll (from the inside roll of paper towel) that is coated with a mirror.
If you shine a flashlight in one you can see light at the far end - even if bent the roll around a corner.

Light pulses move easily down the fiber-optic line because of a principle known as total internal reflection. "This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the fiber-optic strand, it is possible to transmit information down fiber lines in the form of light pulses

1. Fiber Optics Training

Although fiber optics training is advertised by many institutions, only some conform to international standards. Fiber optics training involves a comprehensive, integrated teaching program that meets the requirements of designers, installers and consumers of fiber optic products.

A vast range of short and long term certificate courses are offered in the field of electro-optic devices and all-optical networking systems. There is an entire branch of engineering dedicated to the training of fiber optics. The optics courses cover all the areas of optical fiber telecommunications and networking systems, optical data communications, optical integrated devices, optoelectronic technology, optical measurements, and micro-fabrication processing for optical devices.

Fiber Optic Association (FOA), an international non-profit association, is one of the leading promoters of professionalism in fiber optics. It offers around 100 certified training programs developed and maintained by experts in the fiber optic business. Certified Fiber Optic Technician (CFOT) and Certified Fiber Optic Specialist (CFOS) are the FOA’s two levels of fiber optic certification. Key features of the courses are fiber optics installation, splicing, testing, and maintenance techniques.

Companies such as NASA, Cisco, Panduit, Daimler-Chrysler and Mead Paper use FOA certification in their own training programs. Fiber Optic Training and Consulting (FNT) and RWM Fiber Optics are among the other important institutes, providing fiber optic training and certification for both specific manufacturers and industry organizations.

Fiber optics courses provide tremendous job opportunities, such as designing components, designing systems, installing networks, training and teaching, and manufacturing fiber, lasers, etc. Regarding worker credentials, designing component jobs usually require holders of degrees in physics or chemistry. Depending on the technical nature of the job, the manufacturing jobs possess differing requirements; some need manual skills and others may require higher technical education. Electronic engineers undertake the design of fiber optics systems. The installing networks job requires people skilled in the process of pulling cables, then splicing and terminating them.