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Fiber Optic Cables 

The development of fiber optics stems directly from the increasing demand in fast data transmission between the various terminals. Its immunity to electromagnetic disturbance and its signal transmission characteristics make it the ideal support for high-speed data transmission.

 

Definition
The optical fiber is a very thin glass cable transmitting light signals on which digital data is carried.

The transmission factor of an optical fiber, given in decibels (dB), defines the data transmission quality.



Composition of a fiber optic cable

The light waves travel along the optical core which is made from silica, melted quartz or plastic. The core diameter ranges from 50 to 200 microns.

The optical cladding traps the light waves inside the core: the light ray travels along by successive reflections on the walls formed by the optical cladding.

The protective covering, generally a layer of plastic 25 to 1000 microns thick, gives the fiber excellent mechanical properties.

 

Protective Covering

 




Optical Cladding



Primary Cladding
  Optical Core  




Rayon Lumineux





Dimensions of fiber optic cables

The dimensions of an optical fiber refers to the diameters of the core and the optical cladding. The most common dimensions are 9/125, 50/125, 62.5/125 and 100/140 microns.

 



Types of Optical Fiber


Monomode optical fiber

The light travels along the very thin core almost in a straight line. This type of fiber is widely used for telecom applications, links over long distances (several km) and in backbones.


Multimode, step-index optical fiber
The core is comparatively wider than the cladding. This type of fiber is very efficient over short distances, but rarely used.


Multimode, graded-index optical fiber
The core and the cladding form successive layers of glass. It is very frequently used for medium distances, local area networks and the main routings in buildings.


Testing

Traction Tests

Force T exerted on the optical cable

These involve an optical cable 328 ft (100 m) long, successively subjected to 3 stretching levels for 10 minutes: To = 220 DaN; Tn = 300 DaN; Tm = 350 DaN.

A stretching level is characterized by a force T applied to the end of the optical cable.

The tests are conclusive when the following 3 points are met:

a. No variation of the transmission factor after the 3 stretches.
b. Zero resultant extension* for To.
c. Resultant extension* for Tm < 59. in. (15 cm) (i.e. < 0.15% of the total length).

*The resultant elongation corresponds to the elongation observed after the forces have been applied on the optical cable.

 



Crushing Tests

 

 

 

F = 30 DaN / cm

Length = 5 m

Crushing force F

The fiber undergoes a force of 30 DaN/cm at 16.4 ft (5 m)from the end of the cable for 5 minutes. The test is successful if:

a. There are no perforations, cracks or breaks in the sheath visible to the naked eye.
b. The variation in transmission factor which characterizes the optical fiber must be zero (to within 0.1 dB).



Curvature Tests

Optical fiber wound around a mandrel

These tests are carried out on a mandrel * of diameter 30 cm. No cracks or folds must be observed after the tests.

*cylinder around which the cables are wound


Advantages

  • The most reliable and secure transmission mode
  • Very high data transmission speed, up to 1 Gb/s
  • Low signal attenuation: transport over long distances
  • Immunity against electromagnetic disturbance
  • No electromagnetic radiation
  • Discrete, 100% secure link
  • Corrosion resistance
 


A Solid Structure
Fiber optics are wrongly considered as being fragile, even though before they are put into use they undergo severe tests defined in the various standards, for example EIA/TIA 568-A.


The Cablofil® Solution
Just like copper cables, optical fiber cables must conform with professional installation standards. Cablofil® offers 3 major advantages:

  • The rounded shape of the wire and a smooth safe edge.
  • A range of customized accessories (Cablexit, EZ Velcro...).
  • Open mesh ensuring easy maintenance and checks of the installation quality.