Optical Fibre Couplig Technique

To increase the efficiency of light coupling we can use fiber launch system, which uses a microscope objective lens to focus the light down to a fine point.

We have two types op coupling technique. They are direct coupling and Lens coupling.

Direct coupling

In this system coupling efficiency is low because the full strength of the out put light is not going through the fiber. 

Lens coupling

 

In lens coupling the light coupling efficiency is high. Because two lenses are can be used to focus light. That means whole source light is going through the fiber. The efficiency is more than 70% percent.