Mahmoud AlSaba 223132

1
King Fahd University of Petroleum and
Minerals Computer science department
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