Network Fiber Optic Cable Fundamentals

fiber optic cable

Lots of devices were working via copper cables before which makes us really crazy ! After network fiber optic cable invented, our networks began to increase their speeds too. We will examine this crazy technology for you step by step.

Advantages Of Network Fiber Optic Cable

  • Extremely high bandwidth
  • Smaller-diameter, lighter-weight cables
  • Lack of crosstalk between parallel fibers
  • Immunity to inductive interference
  • High-quality transmission
  • Low installation and operating costs

Network Fiber Optic Cable Structure


Thin glass center of the fiber where the light travels


Outer optical material surrounding the core that reflects the light back into the core


Plastic coating that protects the fiber from damage and moisture


Fiber Optic Cable Classification



Network Fiber Optic Cable Types

G.651 – MMF – Multi-mode fiber

  • Large(r) core: 50-62.5 microns in diameter
  • Transmit infrared light (wavelength = 850 to 1,300 nm)
  • Light-emitting diodes

G.652 – SMF – Single mode fiber

  • Small core: 8-10 microns in diameter
  • Transmit laser light (wavelength = 1,200 to 1,600 nm)
  • Laser diodes

Internal Reflection Of Fiber


Light travels through the core constantly bouncing from the cladding


A light wave can travel great distances because the cladding does not absorb light from the core

Signal degradation

Mostly due to impurities in the glass


Internal Reflection Of Fiber


Attenuation wavelength graphic

Network Fiber Optic Cable Relay System

Optical transmitter

Produces and encodes the light signal

Optical amplifier

May be necessary to boost the light signal (for long distances)

Optical receiver

Receives and decodes the light signal

Optical fiber

Conducts the light signals over a distance

Fiber Optic Relay


A transmitter and a receiver in a single housing

Practical implementation:
Transceivers typically come as SFP small-Form-factor Pluggable unit


Network Fiber Optic Cable Connectors

Fiber Optic Connectors


  • Good alignment/correct orientation
  • Present at the termination point of the fiber
  • Always introduce some loss

Connector types

  • Amount of mating cycles
  • LC, FC, SC, …

Color code

  • APC – green
  • PC – blue

Joining Fibers – Splices

Mechanical splicing

  • Aligning and orienting the fibers, then clamp the fibers in place.

Fusion splicing

  • Aligning and orienting the fibers, then fuse (melt) the fibers.
  • Using an electric arc.

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