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Optical Fiber Cable V2

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Pratyush Srivastava
Pratyush Srivastava

This document provides an overview of optical fiber cables. It begins with a brief introduction describing optical fibers as flexible, transparent fibers made of silica or plastic that guide light using total internal reflection. The document then covers the history of optical fibers, their construction including the core, cladding, buffer and jacket. It discusses concepts such as critical angle, total internal reflection, transmission modes, acceptance angle and numerical aperture. The document also summarizes types of losses, dispersion, fiber optic communication systems, and comparisons of fiber optic, copper and coaxial cables. It concludes with applications and references.

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WELCOME TO SEMINAR ON
MADE BY - PRATYUSH EC 42 (Roll No.-35) OPTICAL FIBER CABLE
CONTENTS Brief Introduction History Optical fiber construction Critical angle & Total Internal Reflection Types of fibers/transmission modes Acceptance angle & acceptance cone Numerical Aperture V-Number Dispersion & its types Attenuation and Losses in Fiber Fiber optic communication Fiber Vs Copper Cable Fiber VS Co-axial Cable Disadvantages Applications References
BRIEF INTRODUCTION Optical fiber is flexible, transparent fiber made of silica or plastic slightly thicker than a human hair It is a form of guided or wired non conducting medium Its working is based on principle of Total Internal Reflection It permits transmission over longer distances and at higher bandwidths than other forms of communication
HISTORY In 1870, Tyndall introduced concept of Total Internal Reflection with a demonstration. In the same year, Alexander Graham Bell, developed a optic voice transmission, which he named the photo phone.
HISTORY (contd.) Later around 1954, Brien, Hopkins & Kapany achieved low loss transmission through 75 cm bundle of thousand fibers Jun-ichi Nishizawa, was the first to propose the use of optical fibers for communications in 1963 Kao and Hockham were first to reduce attenuation in optical fibers below 20 (dB/km), making it a practical communication medium which earned Kao the Nobel Prize in Physics in 2009.
OPTICAL FIBER CONSTRUCTION Core Glass or plastic with a higher index of refraction than the cladding Carries the signal Cladding Glass or plastic with a lower index of refraction than the core Buffer Protects the fiber from damage and moisture Jacket Holds one or more fibers in a cable
CRITICAL ANGLE & TOTAL INTERNAL REFLECTION Critical angle is angle of incidence in denser medium for which angle of refraction in rarer medium is 90 degrees. Total internal reflection-If angle of incidence in denser medium is increased beyond critical angle , then ray of light is reflected back completely into denser medium.
OPTICAL FIBER TRANSMISSION MODES/ TYPES OF FIBERS
TYPES OF FIBERS (contd.) Multimode step-index fiber the reflective walls of fiber move light pulses to receiver Multimode graded-index fiber acts to refract light toward center of fiber by variations in density Single mode fiber the light is guided down center of an extremely narrow core
TYPES OF FIBERS (contd.)
SINGLE MODE FIBER Advantages: Minimum dispersion: all rays take same path, same time to travel down the cable. A pulse can be reproduced at the receiver very accurately. Less attenuation, can run over longer distance without repeaters. Larger bandwidth and higher information rate Disadvantages: Difficult to couple light in and out of the tiny core Highly directive light source (laser) is required Interfacing modules are more expensive
MULTIMODE FIBER Multimode step-index Fibers: inexpensive easy to couple light into Fiber result in higher signal distortion lower TX rate Multimode graded-index Fiber: intermediate between the other two types of Fibers
ACCEPTANCE ANGLE Acceptance angle is maximum angle at which a light ray enters into core and propagate through it in zigzag path Acceptance angle
ACCEPTANCE CONE If all possible direction of acceptance angle are considered at same time we get a cone corresponding to surface known as acceptance cone
NUMERICAL APERTURE It defines gathering capability of fiber mathematically expressed as sine of acceptance angle High Numerical Aperture increases dispersion hence low Numerical Aperture is desirable
V- NUMBER No. of modes supported by optical fiber is obtained by cut-off condition known as normalized frequency or V-Number Number of modes (N) = 遜 V族 V- number can be reduced either by reducing numerical aperture or by reducing diameter of fiber
DISPERSION & ITS TYPES Dispersion is the spreading out of a light pulse as it travels through the fiber It is of two main types: Intermodal or Modal Dispersion Intra modal or Chromatic Dispersion
INTERMODAL OR MODAL DISPERSION Spreading of a pulse because different modes (paths) through the fiber take different times Only happens in multimode fiber Reduced, but not eliminated, with graded-index fiber
INTRA MODAL OR CHROMATIC DISPESRSION Different wavelengths travel at different speeds through the fiber This spreads a pulse in an effect named chromatic dispersion Chromatic dispersion occurs in both single mode and multimode fiber It is of two types 1) Material Dispersion which is wavelength based effect caused by glass of which fiber is made 2) Waveguide Dispersion occurs due to change in speed of wave propagating through waveguide
ATTENUATION Modern fiber material is very pure, but there is still some attenuation The wavelengths used are chosen to avoid absorption bands -850 nm, 1300 nm, and 1550 nm -Plastic fiber uses 660 nm LEDs
LOSSES IN FIBER Absorption Losses- due to material, impurities & atomic defects in glass fiber Geometric Effects- due to manufacturing defects like irregular diameter of core Rayleigh Scattering- Change in local refractive index due to local microscopic variation density It is a scattering loss
FIBER OPTIC COMMUNICATION Input Signal Coder or Converter Light Source Source-to-Fiber Interface Fiber-to-light Interface Light Detector Amplifier/Shaper Decoder Output Fiber-optic Cable Receiver TX, RX, and Fiber Link Transmitter
FIBER OPTIC COMMUNICATION (contd.) Light source: Amount of light emitted is proportional to the drive current Two common types: LED (Light Emitting Diode) ILD (Injection Laser Diode) Sourceto-fiber-coupler (similar to a lens): A mechanical interface to couple the light emitted by the source into the optical fiber Light detector: PIN (p-type-intrinsic-n-type) APD (avalanche photo diode) Both convert light energy into current. Note- For long links,repeaters are used to compensate for
FIBER VS COPPER CABLE Smaller size & weight Greater capacity Faster communication Transmit over Longer distances Can be used for both analog & digital transmission Broader Bandwidth more data per second
FIBER VS COPPER CABLE (CONTD.) Immunity to Electromagnetic Interference Low attenuation/transmission loss over long distances Electrical Insulator Lack of costly metal conductor Dielectric waveguide Signal Security
FIBER VS CO-AXIAL CABLE More information carrying capacity with higher data rates and fidelity Greater transmission speed Smaller in size and light in weight Easier to handle and install Immune towards environmental hazards & electromagnetic interference Higher Bandwidth Economical Low signal loss
DISADVANTAGES Cumulative losses due to large size of fiber couplers Hazardous emissions like glass shards & optical radiation Requires technicians with special expertise for installation & maintenance
APPLICATIONS Used in Cable T.V. , HDTV, LANs & CCTV systems Used in Optic Fiber Communication for transmission of analog & digital data Used in Imaging Optics & Spectroscopy Used in illumination applications Used in various military applications Fiber optic sensors & couplers
REFERENCES Govind P. Agrawal, Fiber Optic Communication Systems, John Wiley, 3rd Edition,2004. R J Hoss and EA Lacy, Fiber optics 2nd edition (Prentice Hall, New Jersey, 1993) John M. Senior, Optical Fiber Communications, PEARSON, 3rd Edition, 2010. Gerd Keiser, Optical Fiber Communications, TMH, 4th Edition, 2008. Joseph C. Plais, Fiber Optic Communication, Pearson Education, 4th Ed, 2004.
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Optical Fiber Cable V2

  • 2. MADE BY - PRATYUSH EC 42 (Roll No.-35) OPTICAL FIBER CABLE
  • 3. CONTENTS Brief Introduction History Optical fiber construction Critical angle & Total Internal Reflection Types of fibers/transmission modes Acceptance angle & acceptance cone Numerical Aperture V-Number Dispersion & its types Attenuation and Losses in Fiber Fiber optic communication Fiber Vs Copper Cable Fiber VS Co-axial Cable Disadvantages Applications References
  • 4. BRIEF INTRODUCTION Optical fiber is flexible, transparent fiber made of silica or plastic slightly thicker than a human hair It is a form of guided or wired non conducting medium Its working is based on principle of Total Internal Reflection It permits transmission over longer distances and at higher bandwidths than other forms of communication
  • 5. HISTORY In 1870, Tyndall introduced concept of Total Internal Reflection with a demonstration. In the same year, Alexander Graham Bell, developed a optic voice transmission, which he named the photo phone.
  • 6. HISTORY (contd.) Later around 1954, Brien, Hopkins & Kapany achieved low loss transmission through 75 cm bundle of thousand fibers Jun-ichi Nishizawa, was the first to propose the use of optical fibers for communications in 1963 Kao and Hockham were first to reduce attenuation in optical fibers below 20 (dB/km), making it a practical communication medium which earned Kao the Nobel Prize in Physics in 2009.
  • 7. OPTICAL FIBER CONSTRUCTION Core Glass or plastic with a higher index of refraction than the cladding Carries the signal Cladding Glass or plastic with a lower index of refraction than the core Buffer Protects the fiber from damage and moisture Jacket Holds one or more fibers in a cable
  • 8. CRITICAL ANGLE & TOTAL INTERNAL REFLECTION Critical angle is angle of incidence in denser medium for which angle of refraction in rarer medium is 90 degrees. Total internal reflection-If angle of incidence in denser medium is increased beyond critical angle , then ray of light is reflected back completely into denser medium.
  • 10. TYPES OF FIBERS (contd.) Multimode step-index fiber the reflective walls of fiber move light pulses to receiver Multimode graded-index fiber acts to refract light toward center of fiber by variations in density Single mode fiber the light is guided down center of an extremely narrow core
  • 11. TYPES OF FIBERS (contd.)
  • 12. SINGLE MODE FIBER Advantages: Minimum dispersion: all rays take same path, same time to travel down the cable. A pulse can be reproduced at the receiver very accurately. Less attenuation, can run over longer distance without repeaters. Larger bandwidth and higher information rate Disadvantages: Difficult to couple light in and out of the tiny core Highly directive light source (laser) is required Interfacing modules are more expensive
  • 13. MULTIMODE FIBER Multimode step-index Fibers: inexpensive easy to couple light into Fiber result in higher signal distortion lower TX rate Multimode graded-index Fiber: intermediate between the other two types of Fibers
  • 14. ACCEPTANCE ANGLE Acceptance angle is maximum angle at which a light ray enters into core and propagate through it in zigzag path Acceptance angle
  • 15. ACCEPTANCE CONE If all possible direction of acceptance angle are considered at same time we get a cone corresponding to surface known as acceptance cone
  • 16. NUMERICAL APERTURE It defines gathering capability of fiber mathematically expressed as sine of acceptance angle High Numerical Aperture increases dispersion hence low Numerical Aperture is desirable
  • 17. V- NUMBER No. of modes supported by optical fiber is obtained by cut-off condition known as normalized frequency or V-Number Number of modes (N) = 遜 V族 V- number can be reduced either by reducing numerical aperture or by reducing diameter of fiber
  • 18. DISPERSION & ITS TYPES Dispersion is the spreading out of a light pulse as it travels through the fiber It is of two main types: Intermodal or Modal Dispersion Intra modal or Chromatic Dispersion
  • 19. INTERMODAL OR MODAL DISPERSION Spreading of a pulse because different modes (paths) through the fiber take different times Only happens in multimode fiber Reduced, but not eliminated, with graded-index fiber
  • 20. INTRA MODAL OR CHROMATIC DISPESRSION Different wavelengths travel at different speeds through the fiber This spreads a pulse in an effect named chromatic dispersion Chromatic dispersion occurs in both single mode and multimode fiber It is of two types 1) Material Dispersion which is wavelength based effect caused by glass of which fiber is made 2) Waveguide Dispersion occurs due to change in speed of wave propagating through waveguide
  • 21. ATTENUATION Modern fiber material is very pure, but there is still some attenuation The wavelengths used are chosen to avoid absorption bands -850 nm, 1300 nm, and 1550 nm -Plastic fiber uses 660 nm LEDs
  • 22. LOSSES IN FIBER Absorption Losses- due to material, impurities & atomic defects in glass fiber Geometric Effects- due to manufacturing defects like irregular diameter of core Rayleigh Scattering- Change in local refractive index due to local microscopic variation density It is a scattering loss
  • 24. FIBER OPTIC COMMUNICATION (contd.) Light source: Amount of light emitted is proportional to the drive current Two common types: LED (Light Emitting Diode) ILD (Injection Laser Diode) Sourceto-fiber-coupler (similar to a lens): A mechanical interface to couple the light emitted by the source into the optical fiber Light detector: PIN (p-type-intrinsic-n-type) APD (avalanche photo diode) Both convert light energy into current. Note- For long links,repeaters are used to compensate for
  • 25. FIBER VS COPPER CABLE Smaller size & weight Greater capacity Faster communication Transmit over Longer distances Can be used for both analog & digital transmission Broader Bandwidth more data per second
  • 26. FIBER VS COPPER CABLE (CONTD.) Immunity to Electromagnetic Interference Low attenuation/transmission loss over long distances Electrical Insulator Lack of costly metal conductor Dielectric waveguide Signal Security
  • 27. FIBER VS CO-AXIAL CABLE More information carrying capacity with higher data rates and fidelity Greater transmission speed Smaller in size and light in weight Easier to handle and install Immune towards environmental hazards & electromagnetic interference Higher Bandwidth Economical Low signal loss
  • 28. DISADVANTAGES Cumulative losses due to large size of fiber couplers Hazardous emissions like glass shards & optical radiation Requires technicians with special expertise for installation & maintenance
  • 29. APPLICATIONS Used in Cable T.V. , HDTV, LANs & CCTV systems Used in Optic Fiber Communication for transmission of analog & digital data Used in Imaging Optics & Spectroscopy Used in illumination applications Used in various military applications Fiber optic sensors & couplers
  • 30. REFERENCES Govind P. Agrawal, Fiber Optic Communication Systems, John Wiley, 3rd Edition,2004. R J Hoss and EA Lacy, Fiber optics 2nd edition (Prentice Hall, New Jersey, 1993) John M. Senior, Optical Fiber Communications, PEARSON, 3rd Edition, 2010. Gerd Keiser, Optical Fiber Communications, TMH, 4th Edition, 2008. Joseph C. Plais, Fiber Optic Communication, Pearson Education, 4th Ed, 2004.