Abstract: The invention relates to a single-mode optical fiber that, for a wavelength of 1550 nm, has an effective area greater than or equal to 60 &mgr;m2, chromatic dispersion lying in the range 3 ps/(nm.km) to 14 ps/(nm.km), a chromatic dispersion gradient in the range 0 ps/(nm2.km) to 0.1 ps/(nm2.km), and a ratio between the effective area and the chromatic dispersion gradient that is greater than or equal to 1000 &mgr;m2.nm2.km/ps, as well as a zero chromatic dispersion wavelength shorter than 1480 nm. The fiber thus has both a large effective area and a shallow chromatic dispersion gradient, and it is thus well suited to wavelength division multiplexed (WDM) transmission. The invention also relates to a WDM optical fiber transmission system that uses such a fiber as the line fiber.

Abstract: A method of manufacturing an optical fiber preform (3) comprising: forming at least one silica-based outer deposition layer (23) by depositing silica on a primary preform (24) constituted by a bar mainly comprising silica and including a silica-based outer peripheral portion (22), the method being characterized in that the viscosity of the outer deposition layer (23) is adjusted to be substantially identical to the viscosity of the outer peripheral portion (22) of the primary preform (24) by adding to the silica, over a substantial portion of the outer deposition layer (23), at least one compound selected from the group formed by the following compounds: CaF2, MgF2, AlF3, B2O3, and Al2O3.

Abstract: A monomode dispersion shifted optical fibre having an effective core area greater than 100 &mgr;m2, characterized in that it has a chromatic dispersion cancellation wavelength &lgr;0 from 1 400 nm to 1 500 nm and low curvature losses.

Abstract: The invention provides a monomode optical fiber having, at a wavelength of 1550 nm: an effective section area greater than or equal to 60 &mgr;m2; chromatic dispersion close to 8 ps/(nm.km); a chromatic dispersion slope of absolute value less than 0.07 ps/(nm2.km). In the range of wavelengths used in a WDM transmission system, typically 1530 nm to 1620 nm, the fiber has chromatic dispersions greater than 7 ps/(nm.km), thereby making it possible to limit non-linear effects. The invention also provides a WDM optical fiber transmission system using such a fiber as a line fiber. The small slope of its chromatic dispersion is an advantage in such a system.

Abstract: A stepped index optical fiber is disclosed having a chromatic dispersion cancellation wavelength less than 1 280 nm or even 1 250 nm. The fiber can be used for wavelength-division multiplex transmission not only in the window around 1 550 nm but also in the window around 1 300 nm. The chromatic dispersion in the second window enables transmission without excessively penalizing non-linear effects. A fiberoptic transmission system which uses the above fiber as line fiber is also disclosed.

Abstract: The invention proposes to fabricate an optical fiber by drawing a preform including several layers, at least one of which has a different viscosity to the other layers at the drawing temperature. The drawing tension is varied during drawing to obtain a fiber having a constant diameter and a varying profile. The chromatic dispersion of the fiber can therefore vary along the fiber. The invention applies to the fabrication of dispersion managed fibers (DMF).

Abstract: In the method, a suspension of silica particles in water is provided, the suspension is gelled, the resulting gel is dried under microwaves, the dried gel is fractioned into silica granules having a diameter lying in the range 10 .mu.m to 1000 .mu.m, having an apparent density of about 0.5 g/cm.sup.3 to 0.6 g/cm.sup.3, and a porosity of less than 20%, and the granules are screened in the range 100 .mu.m to 500 .mu.m. The suspension in water of silica particles is made by mixing silica soots having a size of less than 0.1 .mu.m and silica grains having a size greater than 1 .mu.m. Its maximum concentration in total weight is greater than that of a suspension of synthetic soots on their own, thereby making it possible to increase the production capacity of the method. Advantageously, the out-of-range granules rejected by the screening are recycled as silica grains for the aqueous suspension, thereby making it possible to increase the accumulated production efficiency of the method.