Optical fiber advantages and labelled diagram

Advantages of optical fiber communication

1. Very large bandwidth, giving high data rates and many channels.
2. Very low signal loss (attenuation), so long distances without repeaters.
3. Immune to electromagnetic interference, radio-frequency interference and crosstalk.
4. High security, because it is difficult to tap.
5. Small, light and flexible, so easy to handle and install.
6. No electrical hazard, no sparks or short-circuits.
7. Economical in the long run; raw material (silica) is abundant.

Diagram of an optical fiber (labelled)

 Cross-section:                Longitudinal section:

     ___________              +-------------------------+
   /  _________  \            | Outer jacket            |
  /  /  _____  \  \           |+-----------------------+|
 |  |  / core \  |  |         || Cladding (n2)         ||
 |  |  \(n1)  /  |  |         ||+---------------------+||
  \  \ \_____/  /  /          ||| Core (n1 > n2)      |||
   \  \_______/  /            ||+---------------------+||
    \___________/             || Cladding (n2)         ||
  jacket > cladding > core    |+-----------------------+|
                              | Outer jacket            |
                              +-------------------------+

• Core: central glass strand (8 to 62.5 µm) that carries the light; refractive index n1.
• Cladding: glass layer around the core (125 µm) with lower index n2 < n1; it keeps light inside by total internal reflection.
• Jacket (buffer coating): plastic layer that protects the fiber from moisture, damage and bending.