Single mode fiber (Single Mode Fiber) : The central fiber core is very thin (the core foot-path is generally 9 or 10 m) ,Can only spread a kind of modal light. So, its intermodal dispersion is very little, suitable for the telecommunication, but material dispersion and waveguide dispersion exist yet, in this way the single mode fiber has higher requirements on spectral width and stability of the light source, spectral width should be narrow, stability is on good terms.

Found later at 1310nm wavelength, the total chromatic dispersion of the single mode fiber was zero. According to loss characteristic of the optic fibre, 1310nm is just a low loss window of the optic fibre. In this way, 1310nm wavelength district becomes a very ideal job window of fiber optics telecommunication, also a main wavelength band of the practical optical fiber communication system now. The specification of 1310nm regular single mode fiber was confirmed while proposing in G652 by International Telecommunications Union ITU-T, so this kind of optic fibre is also called G652 optic fibre.

Refer to OH (water peak) above Absorption,have 1520nm range to loss by peak 900~1300nm and 1340nm, call water peak phenomenon. Water peak single mode cable of TeraSPEEDTM that the general company of U.S.A.’s health offers, is solving this problem at present, TeraSPEED system passes the influence factor of dispelling 1400nm water peak, thus has offered more extensive transmission bandwidth to user, users can use all wave bands from 1260nm to 1620nm freely, so the transmission channel rises to 400 from 240 of before, there are the characteristics than traditional single mode fiber, have upgraded to CWDM thick wavelength division multiplexing of 100G bandwidth technologically and laid a solid foundation for future, TeraSPEED solution is the garden / one grade of ideal backbone fiber optic systems in the city.