FIBER OPTICS

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• FIBER OPTICS

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Increase in Bitrate-Distance Product
Agrawal-Fiber Optic Communications
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Progress In Lightwave Communication Technology
Agrawal-Fiber Optic Communications
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Waveguide Basics

• Light is guided by a medium with a higher
  refractive index (Core) surrounded by that with
  a lower one (Cladding)
• Step-index
• Numeric aperture (NA) sine of the largest
  acceptance angle
• Typically, NA0.15 for single mode fiber (SMF)
  and 0.3 for multimode fiber (MMF).

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Optical Fiber

• Some Typical Dimension
• Single Mode Fiber (SMF) 8 µm core
• MultiMode Fiber (MMF) 50, 62.5, 85, 100, 200 µm
  core
• Index profile
• Step vs. Graded vs. multi-step

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Graded index
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Optical Loss
Agrawal-Fiber Optic Communications
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Dispersion

• Different components of transmitted signal travel
  at different velocities in the fiber and arrive
  at different times at the receiver
• Modal dispersion different modal components of a
  pulse travel at different velocities
• Chromatic dispersion different spectral
  components of a pulse travel at different
  velocities
• Material dispersion due to l-dependence in doped
  silica (or any other core material)
• Waveguide dispersion due to waveguide design
• Polarization dispersion different polarization
  components of a pulse travel at different
  velocities

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Multimode Fiber Limitation Modal Dispersion
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Multimode Fiber Limitation Modal Dispersion
Modal Dispersion is critical in MMF.
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