Optical fiber
- 1. Presented by : Pradhan Rishi Sharma Lakshmi narain college of technology Topic: Optical Fiber
- 2. Brief flow of presentation 1. Introduction 2. What are Optical Fibers? 3. Evolution of optical fiber 4. Structure of optical fiber 5. Workings principle of optical fiber 6. Classification of optical fiber 7. Optical fiber communication system 8. Advantages / Disadvantages of Optical fiber 9. Applications of Optical fiber 10. Conclusion
- 3. Evolution of optical fiber • 1880 – Alexander Graham Bell • 1930 – Patents on tubing • 1950 – Patent for two-layer glass wave-guide • 1960 – Laser first used as light source • 1965 – High loss of light discovered • 1970s – Refining of manufacturing process • 1980s – OF technology becomes backbone of long distance telephone networks in NA.
- 4. What is optical Fiber? • An optical fiber is a hair thin cylindrical fiber of glass or any transparent dielectric medium. • The fiber which are used for optical communication are wave guides made of transparent dielectrics. • Its function is to guide visible and infrared light over long distances.
- 5. Structure of optical fiber
- 6. • Core – central tube of very thin size made up of optically transparent dielectric medium and carries the light form transmitter to receiver. The core diameter can vary from about 5um to 100 um. • Cladding – outer optical material surrounding the core having reflecting index lower than core. It helps to keep the light within the core throughout the phenomena of total internal reflection. • Buffer Coating – plastic coating that protects the fiber made of silicon rubber. The typical diameter of fiber after coating is 250-300 um.
- 7. Working principle Total Internal Reflection • When a ray of light travels from a denser to a rarer medium such that the angle of incidence is greater than the critical angle, the ray reflects back into the same medium this phenomena is called total internal reflection. • In the optical fiber the rays undergo repeated total number of reflections until it emerges out of the other end of the fiber, even if the fiber is bent.
- 8. The arrow and the bent pencil
- 9. Total internal reflection in optical fiber
- 10. Classification of optical fiber • Optical fiber is classified into two categories based on :- 1) The number of modes, and 2) The refractive index
- 11. On the basis of number of modes:- on the basis of number of modes of propagation the optical fiber are classified into two types: (i) Single mode fiber (SMF) and (ii) Multi-mode fiber (MMF) (•)Single-mode fibers – in single mode fiber only one mode can propagate through the fiber. This type of fiber has small core diameter(5um) and high cladding diameter(70um) and the difference between the refractive index of core and cladding is very small. There is no dispersion i.e. no degradation of signal during travelling through the fiber. (•)The light is passed through the single mode fiber through laser diode.
- 12. • Multi-mode fiber :- • Multi mode fiber allows a large number of modes for the light ray travelling through it. • The core diameter is (40um) and that of cladding is(70um) • The relative refractive index difference is also larger than single mode fiber. • There is signal degradation due to multimode dispersion. • They are not suitable for long distance communication due to large dispersion and attenuation of the signal.
- 13. Refraction at a plane surface
- 14. Refraction Refraction is the changing direction of light when it goes into a material of different density
- 15. On the basis of Refractive index • There are two types of optical fiber:- • (i) Step-index optical fiber • (ii) Graded-index optical fiber • Step
- 16. Step index fiber • The refractive index of core is constant • The refractive index of cladding is also constant • The light rays propagate through it in the form of meridiognal rays which cross the fiber axis during every reflection at the core cladding boundary.
- 17. Graded Index fiber • In this type of fiber core has a non uniform refractive index that gradually decrease from the centre towards the core cladding interface. • The cladding has a uniform refractive index. • The light rays propagate through it in the form of skew rays or helical rays. They do not cross the fiber axis at any time.
- 19. Disadvantage 1) Highly skilled staff would be required for maintenance 2) Only point to point working is possible on optical fiber 3) Precise and costly instruments would be required 4) Costly if under utilized. 5) Accept unipolar codes only. 6) Jointing of fiber and splicing is also time consuming.
- 20. Applications • In telecommunication field • In space applications • Broadband applications • Computer applications industrial applications • Mining applications • In medical applications • In military applications etc. • Optical fiber have wider range of application in almost all field, some are been specified below
- 21. • Optical fiber have wider range of application in almost all field, i.e. in medical, electronics, military etc .some are been specified below • Medical • Military • Electronics IBM microprocessors
- 22. The Endoscope There are two optical fibres One for light, to illuminate the inside of the patient One for a camera to send the images back to the doctor. Key hole surgery
- 23. Conclusion This concludes our study of optical fiber communications have looked at how they work and how they are made. We have examined the properties of fibers, and how fibers are joined together. Although this presentation does not cover all the aspects of optical fiber work it will have equipped you knowledge and skills essential to the fiber optic industry.
- 24. THANK YOU