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Optical FiberAUTO3160 - Optics and SpectroscopySpring 2012

Miguel Angel ChourioMasters degree in Telecommunication Engineering University of Vaasa, Finland What is a Optical Fiber Single Mode Optical Fiber Multimode Optical FiberSingle mode Vs. Multimode FiberSnews Law - Total Internal ReflectionHow is glass optical Fiber made ApplicationsConclusionsReferences

INDEX

Optical FiberOptical Fiber uses glass to guide the light impulses from source to destination. Optical Fiber provides a very large bandwidth data rates.

Based on its requirements and needs, Networks communication are implemented asCopper Optical Fiber Wireless (Signal are propagated over the air)

Glass Fiber Structure The core vary its dimensions either the fiber is single or multimode.

Light enter into the core and its cladding along the fiber The Cladding surronds or cover the core and is designed to prevent light loss from the fiber.

Since the light can only travel in one direction over the optical cable, two fibers are required to support full duplex operations Ray Light explanationTypically, the core size on Multiple Fiber are large enough so that, multiple light ray can enter to the core at different angles along the fiber.

Multimode fiber employ Light Emitting Diodes (LEDs) with its proper angles to represent the transmitted data as bits along the media. Due the light enters the fiber at different angles, it takes different amount of time to travel down the fiber, and it may become confuse at the receiver side. This effect known as modal dispersion, limit the length of multimode fiber segments.

Ray Light explanationIn Single Fiber, the core is so tiny that only one light ray which is perpendicular to the cable may be propagate along.

Single Fiber employs a single Ray of Light as source generator to propagate the signals, because the laser is uni-directional and travels along the center of the fiber.

Single mode vs. Multimode Fibers

Single-ModeMultimodeSmall core Less dispersion Carry a single ray of light, usually generated from a laser.Employ for long distance applications (100Km)Uses as Backbone and distances of several thousands meters. Larger core than single mode cable.Allows greater dispersion and therefore, loss of signal. Used for shorter distance application, but shorter than single-mode (up to 2Km)It uses LED source that generates differtes angles along cable. Often uses in LANs or small distances such as campus networks. Waveguide calculation of Fiber ModeHere is fiber mode calculation based on Waveguide Calculation by Fiber Optics for Sale Company (USA)V number determines the numbers of guided modes.

When V number is smaller than 2.405 only one mode can be guided by the fiber, this is called single mode fiber. When V Numer is larger than 2.405 severals modes can be guided by the fiber. As higer V number as larger number of modes, this is called Multimode Fiber

Multimode Fibers is more complex The multimode fiber keeps the same structure as single mode unlike the sieze of the core glass is bigger.

Refractive index profile in multimode fibersThe x (axes )shows fiber raduis The y (axes ) shows refractive indexThe core usually has a refractive index n1 = 1.48The cladding has a refractive index n2 = 1.06

This is called Step-index fiberSnews Law - Total Internal ReflectionSnews Law describe the relation between the angles of incidents and refractions. When the Light Ray pass from a higher index material to a lower index material, light refraction occurs. When light incidents at interface between the core and the cladding has differents angles some power are reflacting back and some power enter into the cladding

As the angle is increases larger than the target no more light enter into the Cladding layer and all the light reflect back into the core. This is called Total Internal Reflection. CoreCladding

Optical Fiber manufacturerGenerally it consists on 2 steps by

Glass Fiber preformFiber Manufacturing Process1st Step a preform is made and it has quite exactly the same proportion core as the cladding material.2nd Step the preform pass through a monitor to deploy the final fiber into a drum to be storage and distributed. Special fiber drawing towerOptical Implementation Technology offers by Yangtze Optical Fibre and Cable Company Ltd. (YOFC) a Chinese company established in May 1988.Referencehttp://en.yofc.com.cn/jjfa/&FrontComContent_list01-1293619915029ContId=279b108f-7f52-4951-a347-9afb3bec0dcb&comContentId=279b108f-7f52-4951-a347-9afb3bec0dcb&comp_stats=comp-FrontComContent_list01-1293619915029.html

Nowadays, Optical Fibers connects the world under the sea and over the land

Basically all digital communications travels via fiber.

A single fiber can carry more communications than the biggest copper cable.

Optical Fibers ApplicationsOptical Fibers ApplicationsTelecommunications | Internet | Fiber at Home Video Streaming | Data Centers | Computer Networks Video and Audio Military | Governments | Airports |HospitalIntelligent | Public transportationsEverywhere

Conclusion Optical Fiber = Optical + Fiber At Speed of LightSingle Mode Fiber provides higher data rates speed and more distance than Single ModeSingle Mode uses a single Ray of Light while Multimode Fiber employ Light Emitting Diodes (LEDs) to propagate the signal. At present, the fiber application might be infinite, however a deep analysis and design is recommended before implement a network. Reference[1] Yangtze Optical Fibre and Cable Company Ltd. (YOFC) http://en.yofc.com.cn/jjfa/&FrontComContent_list01-1293619915029ContId=279b108f-7f52-4951-a347-9afb3bec0dcb&comContentId=279b108f-7f52-4951-a347-9afb3bec0dcb&comp_stats=comp-FrontComContent_list01-1293619915029.html

[2] CISCO Networking Academy Program CCNA 1 and 2 book, 3rd Edition, Indianapolis CISCO press, 2003.

[3] About Optical Fiber, link: http://en.wikipedia.org/wiki/Optical_fiber

[4] Eugene Hecht Optics , International Edition, Pearson Education

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