A Project Reporton
(Localization and Rectification of optical fiber faults )as part of vocational training
Submitted to:- Presented by:-Smt A.Dhanak Namrata pandey Nikita karangle
Yasmeen shah
4th semester(cse)
CCET,Bhilai(C.G)SESSION(2014)
INDEXoIntroductionoHistoryoConstruction of optical fiberoPrinciple of optical fiberoTypes of optical fiberoLocalization of optical fiber faultoOptical fiber faultsoReasons of faultoRectification of optical Instrument usedoScope for future
Optical fiber An optical fiber is a flexible, transparent fiber made of very pure glass {silica}.It acts as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. Optical fibers are widely used in fiber-optics communications, which permits transmission over longer distances and at higher bandwidths(data rates) than other forms of communication.
History
Daniel Colladon first described this “light fountain” or “light pipe” in an 1842 article titled On the reflections of a ray of light inside a parabolic liquid stream. This particular illustration comes from a later article by Colladon, in 1884.
Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated
by Daniel Colladon and Jackquse Babinet in Paris in the early 1840s.
Daniel colladon working with his collegue
Construction of Optical Fiber
CORE:-The fiber core is made of silica glass and is the central part of the fiber optic cable that carries the light signal. They are hair-thin in size and the diameter of the fiber core is typically 8 μm for single mode fiber, and 50m or 62.5 m for multi mode fiber core.
CLADDING:-The cladding is also made of glass, and is the layer that surrounds the fiber core. Together, they form a single solid fiber of glass that is used for the light transmission. The diameter of the cladding is typically 125 μm.
BUFFER:-
The buffer is third layer, buffer coatings are UV-cured urethane acrylate composite materials applied to the outside of the fiberduring the drawing process. The coatings protect the very delicate strands of glass fiber
JACKET:-
The last layer is the cable jacket which are comprised of different materials depending on the choice of the end user and its application. They serve only for mechanical protection to the mechanical core and cladding inside
Figure showing parts of optical fiber
Principle of Optical Fiber
An optical fiber is a cylindrical dielectric waveguide (non-conducting waveguide) that transmits light along its axis, by the process of total internal reflection. The fiber consists of a core surrounded by a cladding layer, both of which are made of dielectric materials. To confine the optical signal in the core, the refractive index of the core must be greater than that of the cladding.
Internal reflection
Type of Optical Fiber
• Single Mode:-In fiber optic communication , a single mode optical fiber also known as mono-mode optical fiber is that fiber which is designed to carry only a single ray of light. Single-mode fibers can have a higher bandwidth than multi-mode fibers but the equipment of single-mode fiber is costlier than multi-mode. Although single-mode fiber are cheaper in bulk.
• Multi-mode:- Multi-mode optical fiber(MM fiber) is a type of optical fiber mostly used for communication over short distances, such as within a building or on a campus. Typical multimode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters—more than sufficient for the majority of premises applications. The equipment used for communications over multi-mode optical fiber is much less expensive than that for single-mode optical fiber.
Figure showing mode…..
Localization of Optical Fiber FaultFor the effective use of Optical Fiber, it would be necessary to detect and localize the fiber failures without delay, and the technique used to detect and localize the fiber failures is known as Localization.
In general, an optical time-domain reflectometer (OTDR) has been used to localize fiber failures.
Fault Localization can be demonstrated by using instruments .Such as optical and metallic time domain reflectometers (OTDR & MTDR).
Optical Fiber Faults
1. The physical cable or connector damage(Mainly for the connector and disconnect the connection cable).
2. The cable physical damage.3. Partial failure of the connector(improper
construction of connectors and cable breakage)
4. Line graph error(twisted pair cable).5. The local cable damage.(mostly due to
poor design or construction technology).
Reason of fault1. Mostly due to improper construction methods or
accidental damage to network cables and other causes. Mainly for the connector and disconnect the connection cable.
2. Mainly due to the tight binding between the short circuit caused the cable, because cable nails embedded in gold scrap, stripping header damaged insulation and cable multi-conductor lead wire insulation faults exposed.
3. Mainly as a result of the cable twisted, bending radius is too small to drag force exceeds the mechanical strength of the cable caused by cable damage , and many more appear in the new wiring project.
Rectification 0f Optical Fiber
As mention above, Optical Fiber has different types of fault, and techniques which are used for recovering the damages of Optical Fiber are known as Rectification 0f Optical Fiber.
Some specific instruments are used for Rectification of Optical Fiber Fault are as follows:- Optical time-domain reflectometer (OTDR). Optical power meter (OPM) . Fusion splicing. Pen-type Visual Fault Locator.
Instruments used
An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber.
An OTDR is the optical equivalent of an electronic time domain reflectometer.
It injects a series of optical pulses into the fiber under test.
1.Optical time-domain Reflectometer(OTDR)
It also extracts, from the same end of the fiber, light that is scattered (Rayleigh backscatter) or reflected back from points along the fiber.
(This is equivalent to the way that an electronic time-domain reflectometer measures reflections caused by changes in the impedance of the cable under test.) The strength of the return pulses is measured and integrated as a function of time, and plotted as a function of fiber length.
2.Optical Power Meter (OPM) An optical power meter(OPM) is a device used to measure the power in an optical signal. The term usually refers to a device for testing average power in fiber optic systems . A typical optical power meter consists of a calibrated sensor, measuring amplifier and display. The sensor primarily consists of a photodiode selected for the appropriate range of wavelengths and power levels.
3.Fusion splicing
Fusion splicing is the act of joining two optical fibers end-to-end using heat .The goal is to fuse the two fibers together in such a way that light Passing through the fibers is not scattered or reflected back by the splice . The process of fusion splicing involves using localized heat to melt or fuse the ends of two optical fibers together , the fibers are placed into the apparatus , aligned, and they fused together.
4.Pen Type Visual Fault Locator
Pen type Visual Fault Locator FLP-8312 is simple, easy to use instruments with stable output designed to locate faults on fiber optic cables. When a break or sharp bend exists in a fiber, the red light from the visible fault locator will indicate the trouble spot. Used with either multimode or single mode fiber, the Visual Fault Locator have many useful applications such as locating troubles in splice trays, patch panels, cable splice points, and tracing fiber runs.
Scope for future
1. A University on (Mar. 2, 2011) has developed the very first optical fiber made with a core of zinc selenide --a light-yellow compound that can be used as a semiconductor.The new class of optical fiber, which allows for a more effective and liberal manipulation of light, promises to open the door to more versatile laser-radar technology. Such technology could be applied to the development of improved surgical and medical lasers.
.2.Better countermeasure lasers used by the military.3.Superior environment-sensing lasers are used to measure pollutants and to detect the dissemination of bioterrorist chemical agents.4.It is found that the new class of fiber provided more versatility not just in the visible spectrum, but also in the infrared --electromagnetic radiation with wavelengths longer than those of visible light.
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