How can I experimentally identify between SI/GI Fibers ?

 

How can I experimentally identify between SI/GI Fibers ?

Probably the easiest way is to measure the communications bandwidth over a sufficient length of fiber. The graded index design has much lower modal dispersion and higher communication bandwidth capability.

It's also possible to measure the near-field or far-field light intensity spatial distribution, but this is trickier because the launch conditions of the light source can have an effect, if you are not careful.

There are many other subtle ways too, but the bandwidth choice is experimentally simple.