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.ppt   FIBER OPTICS BASED COMPUTER.ppt (Size: 657 KB / Downloads: 907)

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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.
In 1870, John Tyndall demonstrated that light follows the curve of a stream of water pouring from a container, it was this simple principle that led to the study and development of applications for this phenomenon. John Logie Baird patented a method of transmitting light in a glass rod for use in an early colour TV, but the optical losses inherent in the materials at the time made it impractical to use. In the 1950's more research and development into the transmission of visible images through optical fibres led to some success in the medical world, as they began using them in remote illumination and viewing instruments. In 1966 Charles Kao and George Hockham proposed the transmission of information over glass fibre, and they also realised that to make it a practical proposition, much lower losses in the cables were essential. This was the driving force behind the developments to improve the optical losses in fibre manufacturing, and today optical losses are significantly lower than the original target set out by Charles Kao and George Hockha
A technology that uses glass (or plastic) threads (fibers) to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves. An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length. Fiber optics is the overlap of applied science and engineering concerned with such optical fibers. Optical fibers are widely used in fiber-optic communication, which permits transmission over longer distances and at higher data rates than other forms of wired and wireless communications. Fibers are used instead of metal wires because signals propagate along them with less loss, and they are immune to electromagnetic interference. Optical fibers are also used to form sensors, and in a variety of other applications.
In fibers with large core diameter, the confinement is based on total internal reflection. In smaller core diameter fibers, (widely used for most communication links longer than 200 meters) the fiber acts as a waveguide. There are many different designs of optical fibers, including graded-index optical fibers, step-index optical fibers which are characteristics of an optical fiber and different types of optical fiber as singlemode fibers (SMF) in which there are three kinds of fibers, non-dispersion shifted fibres (NDSF), nonzero dispersion-shifted fibers (NZDSF) and dispersion-shifted fibers (DSF), multimode fibers (MMF), birefringent polarization-maintaining fibers (PMF) and more recently photonic crystal fibers (PCF), with the design and the wavelength of the light propagating in the fiber dictating whether or not it will be multi-mode optical fiber or single-mode optical fiber. Because of the mechanical properties of the more common glass optical fibers, special methods of splicing fibers and of connecting them to other equipment are needed. Manufacture of optical fibers is based on partially melting a chemically doped preform and pulling the flowing material on a draw tower. Fibers are built into different kinds of cables depending on how they will be used.
Because of the Low loss, high bandwidth properties of fiber cable they can be used over greater distances than copper cables, in data networks this can be as much as 2km without the use of repeaters. Their light weight and small size also make them ideal for applications where running copper cables would be impractical, and by using multiplexors one fibre could replace hundreds of copper cables. This is pretty impressive for a tiny glass filament, but the real benefits in the data industry are its immunity to Electro Magnetic Interference (EMI), and the fact that glass is not an electrical conductor. Because fibre is non-conductive, it can be used where electrical isolation is needed, for instance between buildings where copper cables would require cross bonding to eliminate differences in earth potentials. Fibres also pose no threat in dangerous environments such as chemical plants where a spark could trigger an explosion. Last but not least is the security aspect, it is very, very difficult to tap into a fibre cable to read the data signals.
fiber optic systems have many attractive features that are superior to electrical systems. These include improved system performance, immunity to electrical noise, signal security, and improved safety and electrical isolation.
Fiber optic transmission systems - a fiber optic transmitter and receiver, connected by fiber optic cable - offer a wide range of benefits not offered by traditional copper wire or coaxial cable. These include:
The ability to carry much more information and deliver it with greater fidelity than either copper wire or coaxial cable.
Fiber optic cable can support much higher data rates, and at greater distances, than coaxial cable, making it ideal for transmission of serial digital data.
The fiber is totally immune to virtually all kinds of interference, including lightning, and will not conduct electricity. It can therefore come in direct contact with high voltage electrical equipment and power lines. It will also not create ground loops of any kind.
As the basic fiber is made of glass, it will not corrode and is unaffected by most chemicals. It can be buried directly in most kinds of soil or exposed to most corrosive atmospheres in chemical plants without significant concern.
Since the only carrier in the fiber is light, there is no possibility of a spark from a broken fiber. Even in the most explosive of atmospheres, there is no fire hazard, and no danger of electrical shock to personnel repairing broken fibers.
Fiber optic cables are virtually unaffected by outdoor atmospheric conditions, allowing them to be lashed directly to telephone poles or existing electrical cables without concern for extraneous signal pickup.
A fiber optic cable, even one that contains many fibers, is usually much smaller and lighter in weight than a wire or coaxial cable with similar information carrying capacity. It is easier to handle and install, and uses less duct space. (It can frequently be installed without ducts.)
Fiber optic cable is ideal for secure communications systems because it is very difficult to tap but very easy to monitor. In addition, there is absolutely no electrical radiation from a fiber.
Fiber optics is a particularly popular technology for local-area networks. In addition, telephone companies are steadily replacing traditional telephone lines with fiber optic cables. In the future, almost all communications will employ fiber optics.
Because of the relative newness of the technology, fiber optic components are expensive. Fiber optic transmitters and receivers are still relatively expensive compared to electrical interfaces. The lack of standardization in the industry has also limited the acceptance of fiber optics. Many industries are more comfortable with the use of electrical systems and are reluctant to switch to fiber optics. However, industry researchers are eliminating these disadvantages.
Standards committees are addressing fiber optic part and test standardization.
The cost to install fiber optic systems is falling because of an increase in the use of fiber optic technology. Published articles, conferences, and lectures on fiber optics have begun to educate managers and technicians. As the technology matures, the use of fiber optics will increase because of its many advantages over electrical systems.
Fiber optic technology is based on the use of light energy to transmit data. Basically, the encoded data is converted from electrical signals to optical light pulses and then transmitted through the medium to its destination, where it is then converted back. From this, we can see that there are basically three main elements in any fiber optic data link: a transmitter, an optical cable (the transmission medium), and a receiver. The transmitter handles the conversion from electrical to light energy, the optical cable carries the light waves, and the receiver handles the conversion from light pulses back to the original electrical format.
After translating the electrical signals, the transmitter uses either a light emitting diode (LED) or an injection laser diode (ILD) to generate the light pulses. Using a lens, this light energy is then sent down the fiber optic cable. The principle that makes this possible is referred to as total internal reflection. According to John Huber in an article in R&D Magazine, 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 (Huber 115). This happens when two materials with different refractive indices cause the angle of incidence to be too large for refraction (bending) of light to take place. Since the light cannot be bent and exit the material, this means that 100 percent is reflected back. Thus, when a fiber optic cable, which consists of a glass or plastic core surrounded by a cladding with a lower refractive index, receives a light ray, the light ray is confined and travels down the core to the receiving end. Simply put, the difference in the materials used for the core and the cladding make an extremely reflective surface at the point where they interface, which makes the principle of total internal reflection possible. This is the fundamental concept behind all fiber optic transmissions.
In addition to the core and the cladding, a fiber optic cable also has an outer jacket that protects it from abrasion and other forces. Most high end cabling will also have a protective buffer and strength material between the cladding and the outer jacket. These outer layers are added to help protect the fragile core and cladding from damage. There are two common types of cabling used for most fiber optic applications: single-mode and multi-mode. Single-mode fiber is generally used for long distance communications. It has a narrower core diameter, generally 8-10 microns, with a 125-micron cladding. Single-mode optical fiber only allows one mode of light to travel down its core. On the other hand, multi-mode fiber generally has a 62.5-micron core diameter, with a 125-micron cladding.
In order to receive the signal and then convert it back to its original format, a fiber optic receiver uses a phototransistor to convert the light energy into an electrical current. This current is then sent into an amplifier in order to boost the electrical signal back to its original level, and then a digitizer circuit is used to convert the signal into the appropriate digital voltage levels to be used by the external logic. At this point, the electronic signal is ready to be received by the communications device, whether it is a switch, router, computer, etc.
Optical fiber communication
Optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters. Additionally, the light signals propagating in the fiber can be modulated at rates as high as 40 Gb/s and each fiber can carry many independent channels, each by a different wavelength of light (wavelength-division-multiplex WDM). In total, a single fiber-optic cable can carry data at rates as high as 14.4 Pb/s (circa 14 million Gb/s). Over short distances, such as networking within a building, fiber saves space in cable ducts because a single fiber can carry much more data than a single electrical cable. Fiber is also immune to electrical interference, which prevents cross-talk between signals in different cables and pickup of environmental noise. Also, wiretapping is more difficult compared to electrical connections, and there are concentric dual core fibers that are said to be tap-proof. Because they are non-electrical, fiber cables can bridge very high electrical potential differences and can be used in environments where explosive fumes are present, without danger of ignition.
Although fibers can be made out of transparent plastic, glass, or a combination of the two, the fibers used in long-distance telecommunications applications are always glass, because of the lower optical attenuation. Both multi-mode and single-mode fibers are used in communications, with multi-mode fiber used mostly for short distances (up to 500 m), and single-mode fiber used for longer distance links. Because of the tighter tolerances required to couple light into and between single-mode fibers (core diameter about 10 micrometers), single-mode transmitters, receivers, amplifiers and other components are generally more expensive than multi-mode components.
Optical fibers can be used as sensors to measure strain, temperature, pressure and other parameters. The small size and the fact that no electrical power is needed at the remote location gives the fiber optic sensor advantages to conventional electrical sensor in certain applications.
Optical fibers are used as hydrophones for seismic or SONAR applications. Hydrophone systems with more than 100 sensors per fiber cable have been developed. Hydrophone sensor systems are used by the oil industry as well as a few countries' navies. Both bottom mounted hydrophone arrays and towed streamer systems are in use. The German company Sennheiser developed a microphone working with a laser and optical fibers.
Optical fiber sensors for temperature and pressure have been developed for downhole measurement in oil wells. The fiber optic sensor is well suited for this environment as it is functioning at temperatures too high for semiconductor sensors (Distributed Temperature Sensing).
Another use of the optical fiber as a sensor is the optical gyroscope which is in use in the Boeing 767 and in some car models (for navigation purposes) and the use in Hydrogen microsensors.
Fiber-optic sensors have been developed to measure co-located temperature and strain simultaneously with very high accuracy. This is particularly useful to acquire information from small complex structures.
A fiber-optic Christmas Tree
Optical fiber is also used in imaging optics. A coherent bundle of fibers is used, sometimes along with lenses, for a long, thin imaging device called an endoscope, which is used to view objects through a small hole. Medical endoscopes are used for minimally invasive exploratory or surgical procedures (endoscopy). Industrial endoscopes are used for inspecting anything hard to reach, such as jet engine interiors.
An optical fiber doped with certain rare-earth elements such as erbium can be used as the gain medium of a laser or optical amplifier. Rare-earth doped optical fibers can be used to provide signal amplification by splicing a short section of doped fiber into a regular (undoped) optical fiber line. The doped fiber is optically pumped with a second laser wavelength that is coupled into the line in addition to the signal wave. Both wavelengths of light are transmitted through the doped fiber, which transfers energy from the second pump wavelength to the signal wave. The process that causes the amplification is stimulated emission.
Optical fibers doped with a wavelength shifter are used to collect scintillation light in physics experiments.
Optical fiber can be used to supply a low level of power (around one watt) to electronics situated in a difficult electrical environment. Examples of this are electronics in high-powered antenna elements and measurement devices used in high voltage transmission equipment.
Understanding the characteristics of different fiber types aides in understanding the applications for which they are used. Operating a fiber optic system properly relies on knowing what type of fiber is being used and why. There are two basic types of fiber: multimode fiber and single-mode fiber. Multimode fiber is best designed for short transmission distances, and is suited 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.
Multimode Fiber
Multimode fiber, 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 angles within the cone of acceptance. This fiber type has a much larger 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
The principle of total internal reflection applies to multimode step-index fiber. Because the coreâ„¢s index of refraction is higher than the claddingâ„¢s index of refraction, the light that enters at less than the critical angle is guided along the fiber.
Three different lightwaves travel down the fiber. One mode travels straight down the center of the core. A second mode travels at a steep angle and bounces back and forth by total internal reflection. The third mode exceeds the critical angle and refracts into the cladding. Intuitively, it can be seen that the second mode travels a longer distance than the first mode, causing the two modes to arrive at separate times.
This disparity between arrival times of the different light rays is known as dispersion, and the result is a muddied signal at the receiving end. For a more detailed discussion of dispersion, see "Dispersion in Fiber Optic Systems;" however, it is important to note that high dispersion is an unavoidable characteristic of multimode step-index fiber. .

Single-mode Fiber
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.
Single-mode fiber has disadvantages. The smaller core diameter makes coupling light into the core more difficult. The tolerances for single-mode connectors and splices are also much more demanding.
What's the difference between single-mode and multi-mode?
With copper cables larger size means less resistance and therefore more current, but with fibre the opposite is true. To explain this we first need to understand how the light propagates within the fibre core.
Light propagation
Light travels along a fiber cable by a process called 'Total Internal Reflection' (TIR), this is made possible by using two types of glass which have different refractive indexes. The inner core has a high refractive index and the outer cladding has a low index. This is the same principle as the reflection you see when you look into a pond. The water in the pond has a higher refractive index than the air, and if you look at it from a shallow angle you will see a reflection of the surrounding area, however, if you look straight down at the water you can see the bottom of the pond. At some specific angle between these two view points the light stops reflecting off the surface of the water and passes through the air/water interface allowing you to see the bottom of the pond. In multi-mode fibres, as the name suggests, there are multiple modes of propagation for the rays of light. These range from low order modes which take the most direct route straight down the middle, to high order modes which take the longest route as they bounce from one side to the other all the way down the fibr
This has the effect of scattering the signal because the rays from one pulse of light, arrive at the far end at different times, this is known as Intermodal Dispersion (sometimes referred to as Differential Mode Delay, DMD). To ease the problem, graded index fibres were developed. Unlike the examples above which have a definite barrier between core and cladding, these have a high refractive index at the centre which gradually reduces to a low refractive index at the circumference. This slows down the lower order modes allowing the rays to arrive at the far end closer together, thereby reducing intermodal dispersion and improving the shape of the signal.
An optical computer is a computer that uses light instead of electricity (i.e. photons rather than electrons) to manipulate, store and transmit data. Photons have fundamentally different physical properties than electrons, and researchers have attempted to make use of these properties to produce computers with performance and/or capabilities greater than those of electronic computers. Optical computer technology is still in the early stages: functional optical computers have been built in the laboratory, but none have progressed past the prototype stage.
Most research project and implimentations focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. This approach appears to offer the best short-term prospects for commercial optical computing, since optical components could be integrated into traditional computers to produce an optical/electronic hybrid. Other research project and implimentations take a non-traditional approach, attempting to develop entirely new methods of computing that are not physically possible with electronics.
An optical computer is a device that uses visible light or infrared beams, rather than electric current, to perform digital computations.Optical computers promise speeds, which will be thousands, even millions of times faster than those of today's most efficient supercomputers.The optical computer could revolutionize computing in much the same way that the semiconductor chip revolutionized electronics 30 years ago.An electric current flows at only about 10 percent of the speed of light.
Fiber optic connectors have traditionally been the biggest concern in using fiber optic systems. While connectors were once unwieldy and difficult to use, connector manufacturers have standardized and simplified connectors greatly. This increasing user-friendliness has contributed to the increase in the use of fiber optic systems; it has also taken the emphasis off the proper care and handling of optical connectors.
Fiber-to-fiber interconnection can consist of a splice, a permanent connection, or a connector, which differs from the splice in its ability to be disconnected and reconnected. Fiber optic connector types are as various as the applications for which they were developed. Different connector types have different characteristics, different advantages and disadvantages, and different performance parameters.
Another important thing to remember in handling fiber optic connectors is that the fiber end face and ferrule must be absolutely clean before it is inserted into a transmitter or receiver. Dust, lint, oil (from touching the fiber end face), or other foreign particles obscure the end face, compromising the integrity of the optical signal being sent over the fiber. From the optical signalâ„¢s point-of-view, dirty connections are like dirty windows. Less light gets through a dirty window than a clean one.
It is hard to conceive of the size of a fiber optic connector core. Single-mode fibers have cores that are only 8-9 µm in diameter. As a point of reference, a typical human hair is 50-75 µm in diameter, approximately 6-9 times larger! Dust particles can be 20 µm or larger in diameter. Dust particles smaller than 1 µm can be suspended almost indefinitely in the air. A 1 µm dust particle landing on the core of a single-mode fiber can cause up to 1 dB of loss. Larger dust particles (9 µm or larger) can completely obscure the core of a single-mode fiber. Fiber optic connectors need to be cleaned every time they are mated and unmated; it is essential that fiber optics users develop the necessary discipline to always clean the connectors before they are mated.
Connector damage can occur if foreign particles are caught in the end face area of mated connectors.Connector cleaning is simply completed by wiping the connector ferrule and end face with some isopropyl alcohol and a lint free tissue. Another option for connector cleaning is the cassette type cleaners which use a dry tape system where the tape is advanced every time the cassette is opened ensuring the clean section of tape is used each time.
The applications of the fiber optics field are still emerging and developing so rapidly that, it is impossible to keep track each and every innovations and inventions. All the above compilations gives idea about the tremendous potential associated with this field.The future is not so distant when scientists and researchers will come up with more and more futuristic products and applications using optical fibers.

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Evolution of Fiber Optic Transmission
The reality of fiber optic transmission had been experimentally proven in the nineteenth century, but the technology began to advance rapidly in the second half of the twentieth century with the invention of the fiberscope, which found applications in industry and medicine, such as in laparoscopic surgery.
After the viability of transmitting light over fiber had been established, the next step in the development of fiber optics was to find a light source that would be sufficiently powerful and narrow. The light-emitting diode (LED) and the laser diode proved capable of meeting these requirements. Lasers went through several generations in the 1960s, culminating with the semiconductor lasers that are most widely used in fiber optics today.
Light has an information-carrying capacity 10,000 times greater than the highest radio frequencies. Additional advantages of fiber over copper include the ability to carry signals over long distances, low error rates, immunity to electrical interference, security, and light weight.
Aware of these characteristics, researchers in the mid-1960s proposed that optical fiber might be a suitable transmission medium. There was an obstacle, however, and that was the loss of signal strength, or attenuation, seen in the glass they were working with. Finally, in 1970, Corning produced the first communication-grade fibers. With attenuation less than 20 decibels per kilometer (dB/km), this purified glass fiber exceeded the threshold for making fiber optics a viable technology.
Innovation at first proceeded slowly, as private and government monopolies that ran the telephone companies were cautious. AT&T first standardized transmission at DS3 speed (45 Mbps) for multimode fibers. Soon thereafter, single-mode fibers were shown to be capable of transmission rates 10 times that of the older type, as well as spans of 32 km (20 mi). In the early 1980s, MCI, followed by Sprint, adopted single-mode fibers for its long-distance network in the U.S.
Further developments in fiber optics are closely tied to the use of the specific regions on the optical spectrum where optical attenuation is low. These regions, called windows, lie between areas of high absorption. The earliest systems were developed to operate around 850 nm, the first window in silica-based optical fiber. A second window (S band), at 1310 nm, soon proved to be superior because of its lower attenuation, followed by a third window (C band) at 1550 nm with an even lower optical loss. Today, a fourth window (L band) near 1625 nm is under development and early deployment.
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Mr. Atmeshkumar S. Patel. Mr. Vikas. P. Gawai
Lecturer (E&TC. Dept.) Lecturer (E&TC. Dept.)
KCES,s college of engg. IT. , Jalgaon. KCES,s college of engg. IT. , Jalgaon

P r iv a cy and security is of increasing concern in
Wireless, wired, Internet and optical communication
networks. Modern optical communication networks, known
as Wavelength Division Multiplexing (WDM), transport
aggregate traffic per single mode fiber has exceeded Tbps.
We also discuss source authentication, sensing of fiber
tapping as well as sensing data-mimicking by intruders. A
security system for optical communication signals Bragg
gratings in each side of the optical link.
A normal optical homodyne link uses a very stable
maximum spectral width consistent with available emitters
and with the dispersion limitation, if any. In the fiber optic
version, bandwidth physically precludes any LO. sends an
unmodulated phase-reference lightwave as well as the signal.
The signal is digitally phase-modulated 180" with respect
distance, which serves as the security key Security, we take
further measures. The transmitter scrambles the carrier is
practically incoherent with the phase reference in the
transmission line that crosses unsecured territory. Receiver, a
matched scrambler acts on the phase-reference wave a
closed-loop tracking system in the receiver keeps its
scrambler in phase lock with the transmitters. Receiver and
transmitter, the master scrambler in the transmitter randomly
varies the parameters that define its scramble function the
T his system uses variable delay lines, whose lengths
are the scramble parameters. Practical systems require
efficient, low noise, single photon avalanche photodiodes
(SPAD’s) to achieve this goal. reports experimental results
from a polarization-encoded system investigate the
performance limits of quantum cryptography systems
operating in the first optical fiber communication window
The results demonstrate the potential for secure quantum key
distribution at Mb_s1 rates over fiber LAN’s also carrying
conventional high-speed (Gb_s1) data channels at a
wavelength of 1.3 _m. public fiber-optical networks. The
secure channel is hidden under the noise floor of the network
thus allowing cryptographic and steganographic security

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With the growth of computing technology the need of high performance Computers (HPC) have significantly increased.The use of light for the transmission of information is far from a new idea. Fiber optics is a relatively new technology that uses rays of light to send information over hair-thin fibers at blinding speeds. These fibers are used as an alternative to conventional copper wire in a variety of applications such as those associated with security, telecommunications, instrumentation and control, broadcast or audio/visual systems.
Optical computing technology is, in general, developing in two directions. One approach is to build computers that have the same architecture as present day computers but using optics that is Electro optical hybrids. Another approach is to generate a completely new kind of computer, which can perform all functional operations in optical mode.
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• Small Size
• Light Weight
• High Bandwidth
• No Short Circuits
• Fewer Repeaters
• Noise Immunity
• Transmission Security

• An optical computer is a device that uses visible light or infrared beams, rather than electric current, to perform digital computations.
• Optical computers promise speeds, which will be thousands, even millions of times faster than those of today's most efficient supercomputers.
• The optical computer could revolutionize computing in much the same way that the semiconductor chip revolutionized electronics 30 years ago.
• An electric current flows at only about 10 percent of the speed of light.
• Connector damage can occur if foreign particles are caught in the end face area of mated connectors.
• Connector cleaning is simply completed by wiping the connector ferrule and end face with some isopropyl alcohol and a lint free tissue.
• Another option for connector cleaning is the cassette type cleaners which use a dry tape system where the tape is advanced every time the cassette is opened ensuring the clean section of tape is used each time.
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Fiber Optics: The Future Of The Internet
Fiber Optics What Is It?

Fiber Optics are cables that are made of optical fibers that can transmit large amounts of information at the speed of light. (
Research Questions
What can fiber optics do for us in the future?
Improve our communication
Faster internet connection
What would the Internet look like if this could happen?
Streaming capabilities
Download capabilities
What is being done to make this transition happen?
Government action
Private Companies at work
Research Resources
Magazines (IEEE)
1961-“Industry researchers Elias Snitzer and Will Hicks demonstrate a laser beam directed through a thin glass fiber. The fiber’s core is small enough that the light follows a single path, but most scientists still consider fibers unsuitable for communications because of the high loss of light across long distances.” (
1970- Researchers find a way to super purify glass fibers.
1980- At&t installs first set of fiber optic cables in major cities.
1988- First transatlantic cable
1996- First transpacific cable
1997- First Fiber Optic Link Around the Globe (FLAG)
Internet Access
Cable and Satellite Television
Decorative Light Source
The Cable
Fiber Optic have three major characteristics
Composed of fibers either glass or plastic and sometimes both
Are very flexible
Have different tips
Outside Jacket

Glass Fibers
Glass Core
Glass Cladding
Ultra Pure Ultra Transparent Glass
Made Of Silicon Dioxide
Low Attenuation
Popular among industries
Plastic Fibers
Core Generally Consists Of Polymethyl Methacrylate (Acrylic Glass) (PMMA) Coated With A Fluoropolymer
High Attenuation
Used Mostly In Automotives
Very Durable
Plastic Clad-Silica (PCS)
Glass Fiber Core sometimes silicone
Cladding is Plastic or silicone
Silicone covering and insulators
Not common
Has Defects
Government Involvement
Private Companies Input
The Future
The Internet
Bandwidths of up to 10Gbps
Streaming Whole Movies in HD
Effortless video conferencing with no lagging
Gaming in HD quality that never lags
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Introduction of Optical fiber:-

Our current “age of technology” is the result of many brilliant inventions
and discoveries, but it is our ability to transmit information, and the
media we use to do it, that is perhaps most responsible for its evolution.
Progressing from the copper wire of a century ago to today’s fiber optic
cable, our increasing ability to transmit more information, more quickly
and over longer distances has expanded the boundaries of our
technological development in all areas.

History of Fiber Optic Technology:-

In 1870, John Tyndall, using a jet of water that flowed from one
container to another and a beam of light, demonstrated that light used

internal reflection to follow a specific
path. As water poured out through the
spout of the first container, Tyndall
directed a beam of sunlight at the path
of the water. The light, as seen by the
audience, followed a zigzag path inside
the curved path of the water. This
simple experiment, illustrated in Figure, marked the first research into guided
transmission of light.

Guiding Mechanism in optical fiber:-
Light ray is injected into the fiber optic cable on the right. If the light
ray is injected and strikes the core-to-cladding interface at an angle
greater than an entity called the critical angle then it is reflected back
into the core. Since the angle of incidence is always equal to the angle of
reflection the reflected light will again be reflected. The light ray will
then continue this bouncing path down the length of the fiber optic
cable. If the light ray strikes the core- to-cladding interface at an angle
less than the critical angle then it passes into the cladding where it is
attenuated very rapidly with propagation distance.

Characteristics of LEDs:-
_ Low Cost
_ Low Power
_ Relatively Wide Spectrum Produced
_ Incoherent Light
_ Digital Modulation
_ Analogue Modulation

Principle of the LASER:-
1.An electron within an atom (or a molecule or an ion) starts in a low
energy stable state often called the “ground” state.
2. Energy is supplied from outside and is absorbed by the atomic
structure whereupon the electron enters an excited (higher energy) state.
3. A photon arrives with energy close to the same amount of energy as
the electron needs to give up reaching a stable state.

Limitations of Optical Fiber:-

1. The terminating equipment is still costly as compared to copper wire.
2. Delicate so has to be handled carefully.
3. Communication is not totally in optical domain, so repeated electric
to optical to electrical conversion is needed.
4. Optical amplifiers, splitters, MUX-DEMUX are still in development
5. Tapping is not possible. Specialized equipment is needed to tap a fiber.


_ The age of optical communications is a new era. In several
ways fiber optics is a pivotal breakthrough from the electric
communication we have been accustomed to. Instead of
electrons moving back and forth over a regular copper or
metallic wire to carry signals, light waves navigate tiny fibres of
glass or plastic to accomplish the same purpose.
_ With a bandwidth and information capacity a thousand times
greater than that of copper circuits, fiber optics may soon
provide us with all the communication technology we could
want in a lifetime, at a cost efficient price.

seminar tips
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17-01-2013, 09:43 AM

to get information about the topic "computer networks" full report ppt and related topic refer the link bellow






seminar tips
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Joined: Oct 2012
28-01-2013, 10:42 AM

to get information about the topic "Optical Computer " full report ppt and related topic refer the link bellow

topicideashow-to-optical-computer-full-seminar and presentation-report-download

topicideashow-to-optical-computing-seminar and presentation-report



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