Sub-comms Cabinet - Components

the thing that makes a fibre single or multi-mode is the core size, the core is the region of denser glass in the centre that traps the light by internal reflection (much in the way that at the correct angles you get a reflection going from under water to air - next time you seem to have a drink in a glass, hold it up and look out through the top surface, note that from some trick angles it looks like a mirror. Cheers. ? Optic fibre is that effect rolled up into a tube so the light is trapped.


In a multimode fibre the core is larger, and the light spreads into many paths ('modes') of slightly different lengths, giving a spread in group velocity and smearing the signal timing, this really only matters over longer distances.

typically the core is 50 to 80  microns wide in a fibre that is 120um overall.


In a single mode fibre the light is more restrained,  (core between perhaps 1/10th diameter at 5 to 8 microns diameter) but the penalty is that the mechanical tolerances the fibre and its connector have to be made to are much tighter or the light misses the target altogether..

So single mode optical parts are harder to manufacture, and so cost  more. But for ultimate fast edged speed and distance it is what you need. Multi mode is slightly more tolerant of dust and alignment errors.

the thing that makes a fibre single or multi-mode is the core size, the core is the region of denser glass in the centre that traps the light by internal reflection (much in the way that at the correct angles you get a reflection going from under water to air - next time you seem to have a drink in a glass, hold it up and look out through the top surface, note that from some trick angles it looks like a mirror. Cheers. ? Optic fibre is that effect rolled up into a tube so the light is trapped.


In a multimode fibre the core is larger, and the light spreads into many paths ('modes') of slightly different lengths, giving a spread in group velocity and smearing the signal timing, this really only matters over longer distances.

typically the core is 50 to 80  microns wide in a fibre that is 120um overall.


In a single mode fibre the light is more restrained,  (core between perhaps 1/10th diameter at 5 to 8 microns diameter) but the penalty is that the mechanical tolerances the fibre and its connector have to be made to are much tighter or the light misses the target altogether..

So single mode optical parts are harder to manufacture, and so cost  more. But for ultimate fast edged speed and distance it is what you need. Multi mode is slightly more tolerant of dust and alignment errors.