Why is singlemode fibre used in telecoms over longer distances?
Singlemode fibre is used extensively in telecoms because of the data rates that are involved. Transmission of data using multimode fibre results in something called modal dispersion, arising from the multiple modes. This weakens the transmitted data, limiting the distances over which it can be transmitted. This effect gets worse as you use faster data rates. The DTS only uses a very broad pulse in comparison with telecoms systems, so modal dispersion has a negligible effect on the DTS performance. Singlemode has to be used for telecoms systems where data can be transmitted at multiple Gigabit/s rates over distances of 100’s of kilometres. Multimode fibre optic cable can be used for more general fibre applications where the distances are much shorter, such as LAN’s.
