Evolution of Fiber Optic Technology

1. Fiber Optic Mahmoud Al-Saba – 223132 Majed Al-Bishi – 216423

2. History of Fiber Optic Technology • People have used light to transmit info. for hundreds of years • The invention of the laser prompted researchers to study the potential of fiber optics  send a much larger amount of data than telephone • first experiment  letting the laser beam transmit freely in air & through different types of waveguides • very large losses in the optical fibers prevented coaxial cables from being replaced  Decrease in the amount of light reaching the end of the fiber

3. Cont: History of Fiber Optic Technology • Early fibers had losses around 1,000 dB/km • In 1969, several scientists concluded that impurities in the fiber material caused the signal loss  Researchers believed it was possible to reduce the losses • By removing the impurities researchersobserve the improvement • In 1970,(corning glass works)* made a multimode fiber with losses under 20 dB/km. in 1972, the company made a high silica-core multimode optical fiber with 4dB/km. • Nowadays, multimode fibers can have losses as low as 0.5 dB/km at wavelengths around 1300 nm *company

4. Introduction • Optical fiber has a number of advantages over the copper wire since it is made glass or plastic • light has a much higher frequency than any radio signal  we can generate, fiber has a wider bandwidth To carry more information at one time

5. Transmitters • transmitters  include an LED(Light-emitting diodes) or laser diode • LED produce incoherent light •  have relatively large emitting areas and as a result are not as good light source •  they are widely used for short distances because they are much more economical

6. Cont: Transmitters • Laser diode  produce coherent light  used for applications that require the transmission of signals over long distances • Important performance specifications • data rate • transmitter rise time • wavelength • spectral width • maximum optical output power

7. Receivers • Receivers are instruments that convert light into electrical signals. • component of an optical receiver is a photo detector that converts light into electricity  use three types of photodiodes • positive-negative (PN) junctions • positive-intrinsic-negative (PIN) photodiodes • avalanche photodiodes (APD)

8. Optical Fiber • Fiber is the medium to guide the light form the transmitter to the receiver. • There are two types: • Multimode Fiber • Single-Mode Fiber

9. Multimode Fiber • In multimode fibers more than one light transmitted at a time. • Fiber diameter ranges from 50-to-100 micron.

10. Multimode Fiber • Multimode Fiber is divided into two types: • Multimode Step-index Fiber • Multimode Graded-index Fiber

11. Multimode Step-index Fiber • Lights are sent at angles lower than the critical angle or straight • Any light angle exceed the critical angle will cause it to penetrate through cladding. • Obviously light with lower angle will reach the end faster than others.

12. Multimode Step-index Fiber • The difference in signals receiving time result in unstable wave light at the receiver. • To avoid this problem there should be spacing between the light pulses  but this will limit the bandwidth. • Used for very short distance

13. Multimode Graded-index Fiber • In this mode reduce the problem with Multimode Step-Index. • All the beams reaching the receiver almost at the same time. • This can be done by slowing down the ones with shorter distance. • This is done in fiber implementation by increasing its refractive index at the center and gradually decreases it toward the edges

14. Single-Mode Fiber • Only one light is transmitted in the fiber. • Diameter ranges from 8.3 to 10 microns. • It has Higher transmission rate. • it can be used for longer distance.

15. Fiber Cables • Advantages of Cabling fiber: • Ease of Handling • Protection • Crush Resistance • Degradation • Types of Fiber Cables: • Loose Tube Cable • Tightly Buffered Cable • Ribbon Cables

16. Wave Division Multiplexing (WDM) • it is a way to send multiple optical signals from deferent source at the same time on one optical fiber. • Used with single mode fiber • How it works: • At the sender the data stream from each Source is assigned an optical wavelength. • The multiplexer modulates each data stream from each Source. • The resulted optical signal generated for each source data stream is placed on its assigned wavelength.

17. Wave Division Multiplexing (WDM) • The resulted signals are simultaneously sent through the fiber. • At the receiver the signal is separated into the original signals according to their different wavelengths by using prisms. • These signals are further demodulated. • Then, The resulting separated data streams are provided to the respective Users.

18. Some Application • Long telecommunication systems on land and at sea to carry many simultaneous telephone calls (or other signals) over long distances. • Links among computers and high resolution video-terminals. • Local area Networks operating at high speeds. • Connections between the telephone N/W and antennas for mobile telephone service. • Interoffice trunks that carry many telephone conversations simultaneously between local and regional switching facilities.

19. Thank you Any Question please