Fibre Optic Technology
When and why would you use fibre optic cabling?
Fibre optic technology basically works as it sounds - it uses glass fibre optic cables to carry a digital signal from a light source. It has a much greater range than traditional copper data cable and doesn't suffer any of the effects of interference with power cables etc.
Multimode and Singlemode
There are two types of fibre optic cable - multimode and singlemode. The main difference is in the way that the technology works - for multimode, the technology is based on LEDs, whereas singlemode is based on LASER technology. Light from a LED can suffer from intermodal interference which corrupts the signal. The effects of this interference increase with range and signal speed. Generally, the maximum range of multimode cable if 250m at 10G.
For these reasons, singlemode is the high-end option. The cable for singlemode is actually cheaper than multimode (since at a smaller diameter cable it contains less glass) but the switches are greater in price and the methods for joining singlemode cable are generally less tolerant to error and require expensive equipment. This means that many companies will not install singlemode.