Optisk monomode fiber med optimeret kromatisk spredning

The fiber has a core extending successively from a center towards a periphery and presenting a variable index profile than a sheath of constant index. A central section of maximum index and a buried section of minimum index has index higher and lower than a sheath index, respectively. A circular index section has an index higher to the sheath index and lower to the central section index. Independent claims are also included for the following: (a) a transmission system on a distance lower at 350 kilometer having a optical fiber; and (b) an association of a part of the metropolitan transmission network on a distance lower at 350 kilometer and another part of access network.