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Optical Fiber

Optical Fiber. Introduction Basic properties of light Optical Fiber Characteristics Optical fiber cables Optical fiber connectors Optical fiber directional couplers Fusion splicing of fiber optics Transmission attenuation Dispersion Optical fiber link Modes Light sources Detectors

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Optical Fiber

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  1. OpticalFiber

  2. Introduction Basic properties of light Optical Fiber Characteristics Optical fiber cables Optical fiber connectors Optical fiber directional couplers Fusion splicing of fiber optics Transmission attenuation Dispersion Optical fiber link Modes Light sources Detectors Optical measurements Fiber networks Contents

  3. 1 Introduction

  4. 1-Transmission Media • There are 3 transmission media • Electric Current via • copper cables • ( twisted pairs- coaxial cables) • Electromagnetic waves • space • Optic Waves via • optical fiber cables

  5. 1880 Alexander G. Bell, Photo phone, transmit sound waves over beam of light . 1930 TV image through uncoated fiber cables. Few years later image through a single glass fiber. 1951 Flexible fiberscope: Medical applications. 1956 The term “fiber optics” used for the first time. 1958 Paper on Laser . 1960 Laser invented . 1967 New Communications medium: cladded fiber. 1960s Extremely lossy fiber: more than1000 dB /km. 1-2 Optical fiber History

  6. 1970 Corning Glass Work NY, Fiber with loss of less than 2 dB/km. 70s & High quality sources and detectors 80s Late 80s Loss as low as 0.16 dB/km. 1990 Northern and western Europe has completed the installation of fiber optic long distance networks, now it is time for the second run. 1992 Field test for fiber optic networks to the homes, FTTH in Europe. 2000 SDH, SONET and ISDN-B . 2009 14 th October , First FTTH to katamia (Cairo )

  7. Small size and light weight . • much wider bandwidth (10 GHz) . • Crosstalk and interference immunity . • Immunity to static interference . • Safety: Fiber is nonmetallic . • Longer lasting (unproven) . • Security: tapping is difficult . • Economics: Fewer repeaters, low cost . • Low transmission loss . • System reliability and ease of maintenance . • Ruggedness and flexibility . 1.3 Optical Fiber Advantages

  8. Higher initial cost in installation . • Interfacing cost . • Strength: Lower tensile strength . • more expensive to repair/maintain . • Tools: Specialized and sophisticated 1.4 Optical Fiber Disadvantages

  9. Difficult jointing of individual fiber segments • (improving continuously by new developments) . • Limited life-time of light sources . • Need for control of production parameters to • obtain ideal fiber dimensions and index profile • The need for additional copper energy cables • may become a necessity. (New developments • increased the distance between repeaters • tremendously: in the year 2000 working systems • containing repeater fields of 140km at 2.1 Gbit • exist)

  10. 1.5 Optical Fiber Link Transmitter Input Signal Coder or Converter Light Source Source-to-Fiber Interface Fiber-opticCable Output Light Detector Fiber-to-light Interface Amplifier/Shaper Decoder Receiver

  11. Economical light source emits at defined wavelength. Fiber optical cable of small loss . Fusion machine for stable splices . Detector of high sensitivity and high responsibility . Electric circuits deal with the optical components . 1.6 Optical Fiber Transmission Requirements

  12. 1.7 Optical fiber Usage • Junction Cables • Transmission Cables • International Cables • SEA ME WE 2 • SEA ME WE 3 • SEA ME WE 4 • South East Asia Middle East West Europe • Local Cables • FTTC • FTTH • Control Networks • Computer Networks ( LAN , WAN )

  13. SeaMeWe-3 The route of the submarine cable (black); the blue segment is terrestrial

  14. SeaMeWe-3 is a submarine cable that connects Karachi, Pakistan to Middle East, Africa and Europe. A major bulk of our trade happens through Karachi and a major bulk of the internet traffic in Pakistan, India and Bangladesh is routed through this cable. • The SeaMeWe is owned by consortium of companies. • A satellite up link would at least ensure a plan B, a fall back plan without having to worry about the maintenance of this under water cable. • Major Arab countries like Saudi Arabia, UAE, Kuwait already have a satellite system in place that helps them redirect their internet traffic when this cable starts to malfunction. As a rising regional economy, its time we put some thought to this.

  15. The route of the submarine cable (red); the blue segment is terrestrial

  16. South East Asia–Middle East–Western Europe 4 (SEA-ME-WE 4) is an optical fibresubmarine communications cable system that carries telecommunications between Singapore, Malaysia, Thailand, Bangladesh, India, Sri Lanka, Pakistan, United Arab Emirates, Saudi Arabia, Sudan, Egypt, Italy, Tunisia, Algeria and France.[1] • It is intended to be a complement to rather than a replacement for the SEA-WE-ME 3 cable. • The cable is approximately 18,800 kilometres long, and provides the primary Internet backbone between South East Asia, the Indian subcontinent, the Middle East and Europe

  17. The SEA-ME-WE 4 system is divided into four segments with • seventeen landing points:[3] Segments Landing points

  18. The SEA-ME-WE 4 cable system was developed by a consortium of 16 telecommunications companies which agreed to construct the project on 27 March 2004.[2] • Construction of the system was carried out by Alcatel Submarine Networks (now Alcatel-Lucent Submarine Networks, a division of Alcatel-Lucent) and Fujitsu.[2] • The eighteen month construction project was completed on 13 December 2005 with a cost estimate of US$500 million.[4][2] • Segment 1 construction, running 8,000 kilometres from Singapore to India, was done by Fujitsu, which also provided the submarine repeater equipment for Segment 4.[4]

  19. The SEA-ME-WE 4 cable system was proposed and developed by the SEA-ME-WE 4 Consortium. The Consortium continues to maintain and operate the system. It • comprises 16 telecommunications companies:[18][4] • Algérie Télécom, Algeria • Bharti Infotel Limited, India • Bangladesh Submarine Cable Company Limited (BSCCL), Bangladesh • CAT Telecom Public Company Limited, Thailand • Emirates Telecommunication Corporation (ETISALAT), UAE • France Telecom - Long Distance Networks, France • MCI, UK • Pakistan Telecommunication Company Limited, Pakistan • Singapore Telecommunications Limited (SingTel), Singapore • Sri Lanka Telecom Limited (SLT), Sri Lanka • Saudi Telecom Company (STC), Saudi Arabia • Telecom Egypt (TE), Egypt • Telecom Italia Sparkle S.p.A., Italy • Telekom Malaysia Berhad (TM), Malaysia • Tunisie Telecom, Tunisia • Tata Communications previously Videsh Sanchar Nigam Limited (VSNL), India

  20. SEA-ME-WE 4 is used to carry "telephone, internet, multimedia and various broadband data applications".[2] • The SEA-ME-WE 3 and the SEA-ME-WE 4 cable systems are intended to provide redundancy for each other.[2] • The two cable systems are complementary, but separate, and 4 is not intended to replace 3.[2] • Both derive from the same series of projects (SEA-ME-WE), but have different emphases. SEA-ME-WE 3 is far longer at 39,000 kilometres[21] (compare to SEA-ME-WE 4's 18,800 kilometres) and extends from Japan and Australia along the bottom of the Eurasian landmass to Ireland and Germany.[22] • SEA-ME-WE 4 has a faster rate of data transmission at 1.28 Tbit/s against SEA-ME-WE 3's 10 Gbit/s.[21]

  21. SEA-ME-WE 4 has a faster rate of data transmission at 1.28 Tbit/s against SEA-ME-WE 3's 10 Gbit/s.[21] • SEA-ME-WE 3 provides connectivity to a greater number of countries over a greater distance, but SEA-ME-WE 4 provides far higher data transmission speeds intended to accommodate increasing demand for high-speed internet access in developing countries .

  22. The cable uses dense wavelength-division multiplexing (DWDM),[1] allowing for increased communications capacity per fibre compared to fibres carrying non-multiplexed signals and also facilitates bidirectional communication within a single fibre. • DWDM does this by multiplexing different wavelengths of laser light on a single optical fibre so that multiple optical carrier signals can be concurrently transmitted along that fibre. • Two fibre pairs are used with each pair able to carry 64 carriers at 10 Gbit/s each.[4] This enables terabit per second speeds along the SEA-WE-ME 4 cable,[2] with a total capacity of 1.28 Tbit/s.[4]

  23. 1.8 Definition of terms The telecommunications industry differentiates between several distinct configurations. The terms in most widespread use today are: FTTN - Fiber-to-the-node - fiber is terminated in a street cabinet up to several kilometers away from the customer premises, with the final connection being copper. FTTC - Fiber-to-the-cabinet or fiber-to-the-curb - this is very similar to FTTN, but the street cabinet is closer to the user's premises; typically within 300m.

  24. FTTB - Fiber-to-the-building or Fiber-to-the-basement - fiber reaches the boundary of the building, such as the basement in an multi dwelling unit, with the final connection to the individual living space being made via alternative means. FTTH - Fiber-to-the-home - fiber reaches the boundary of the living space, such as a box on the outside wall of a home. FTTP - Fiber-to-the premises - this term is used in several contexts: as a blanket term for both FTTH and FTTB, or where the fiber network includes both homes and small businesses

  25. 1.9 FTTH SERVICES

  26. 2 Basic Properties of Light

  27. 2.1 Sine Wave Frequency C = λ f λ = C / f f = C / λ • Frequency (f) is the number of complete oscillations in • one second . • Wavelength (λ) is the distance between two consecutive • tops or bottoms (nm) . • The optical fiber wavelength ranges from 820- 1600 nm .

  28. In free space (vacuum) C° = 3 × 108 m/sec . Glass is more dense than air . Speed of light in air is more than the speed of light in any other material . 2.2 Speed of Light

  29. Examples 1- λ = 1 µ m , f = ? 2- f = 300 GHz , λ = ? Solution 1- f = C / λ = 3× 108 / 1× 10-6 = 3 × 1014 Hz = 300 T Hz 2- λ = C / f = 3× 108 / 300× 109 = 1× 10-3 = 1 m m

  30. 2.3 The Electromagnetic Spectrum • In the field of optical communications, (λ) is indicated instead of the frequency (f). • Visible light occupies the wavelength range from 380 nm (violet) to 780 nm (red). • Optical telecommunications uses the near IR range around the wavelength 1μm. This corresponds to a frequency in the order of magnitude of 1014 Hz.

  31. When light falls to the interface of two media , there will be penetration or reflection or both . 2.4 Reflection & Penetration

  32. Reflection depends on the surface . If the surface is smooth , there will be “regular reflection “. 2.4.1 Regular reflection

  33. If the surface is rough , then there will be “ diffuse reflection “ . 2.4.2 Diffuse reflection

  34. 2.4.3 Total reflection

  35. LAW OF REFLECTION 2.4.4 Law of reflection

  36. 2.5 Refraction • Penetration of light ray from one medium to another. • Speed of light differs from medium to another. • Angle of refraction depends on the optical dense of the second medium.

  37. REFRACTED RAY OF SPEED 2.5.1 Refraction index • The speed of light in any other medium except vacuum is less than Co • The ratio between the speed of light in free space and in a medium is called the refractive index (n) . • n = Co / C = speed of light in free space / speed of light in the medium . • The less the speed the more the refractive index .

  38. 2.5.2 Comparison between (n) in different media n is always > 1

  39. Examples Calculate the refractive index (n) if 1- C = 2× 105 Km /s 2- C = 0.5 C0 Solution 1-n = Co / C = 3× 108 / 2× 108 = 1.5 2- n = Co / C = Co / 0.5 Co = 2

  40. Example Calculate the speed of light in a medium of refractive Index 1.48 Solution C = Co / n = 3× 108 / 1.48 = 2.027 × 108 m /s

  41. 2.5.3 Snell’s law ( Law of refraction ) Where α = incident angle Θ = refraction angle n1 = refractive index of the first medium n2= refractive index of the second medium Θ= sin-1 [ sin α . n1/n2 ]

  42. Example n1 = 1, n2 = 1.5 , α = 30 0 Θ = ? solution Θ= sin-1 [ sin α . n1/n2 ] Θ= sin-1 [ sin 30 . 1/1.5 ] Θ= sin-1 [ 0.5 * 0.66 ] Θ= sin-1 0.33 = 19.47 0

  43. TOTAL INTERNAL REFLECTION 2.6 Total Internal Reflection • At a certain angle of incidence the angle of reflection becomes 90o (total internal reflection) • Total internal reflection occurs only when the medium of incidence is optically denser and at certain incidence angle (critical angle)

  44. EXAMPLE n1 = 1 .5 , n2 = 1 , Θ = 90 0 α c = ? SOLUTION Snell’s law sin α c / sin Θ = n2 / n1 sin α c = 1/ 1.5 = 0.67 α c = 42 0

  45. 2.7 Reflection Cases • Incident ray may : • Reflect • Have total internal • reflection • Refract Law of Refraction

  46. 2.8 Fresnel Loss • When light falls perpendicularly to a surface , it will not fully penetrate the surface but a small part of this light will be reflected . • It is called Fresnel reflection .

  47. 2.8.1 Reflection factor n2-n1 n2+n1 Reflection Factor = ρ= ( ) 2 ρ = ( ) 2 = 0.04 1.5-1 1.5+1

  48. 2.9Rayleigh scattering • results from the existence of small • particles and inhomogeneties which are • illuminated and thereby emit light in all • directions. • The emitted light is called Tyndall-light • This scattering is proportional to λ-4 .

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