Abstract: An optical transmission fiber for use in a metropolitan or access network is disclosed. The transmission line includes a fiber being single mode at a first operating wavelength of around 1310 nm and a second operating wavelength of around 1550 nm. The dispersion of the fiber is negative at one of the first and second operating wavelengths and positive at the other of the first and second operating wavelengths, with an absolute value of between about 5 ps/nm/km and 15 ps/nm/km. The fiber also has a zero dispersion wavelength that is located between the first and second operating wavelengths, and an effective area at a wavelength around 1550 nm greater than about 60 &mgr;m2. The cabled fiber has a cutoff wavelength less than about 1300 nm. The fiber allows wavelength division multiplexing (WDM) operation in both the bands (1310 nm and 1550 nm) by reducing nonlinear effects such as four-wave mixing (FWM).

Abstract: An induction furnace capable of drawing large diameter preforms of up to 130 mm is described. The induction furnace has top and bottom chimneys surrounding the entire preform during operation of the furnace with an inert conditioning gas which is introduced into the top chimney and flows downward through the furnace body and bottom chimney without significant turbulence. A distributor ring inside the top chimney redirects flow from a circumferential direction to a downward direction. The top chimney also includes a resilient seal to releasably hold the top of the preform. The bottom chimney has a smoothly decreasing cross-sectional area preventing turbulence at the furnace exit. The furnace insulation is preferably a rigid self-supporting graphite cylinder. A method of drawing large diameter preforms either to an optical fiber or to a preform of smaller diameter using such a furnace is also described.

Abstract: An optical transmission fiber has a refractive index profile with an area of increased index of refraction at the inner core of the fiber, an annular region positioned radially outward from the inner core with an index of refraction exceeding the index of the inner core, and at least a low dopant content region in a cross-sectional region between the inner core and the annular region. A low loss cladding layer surrounds the core region. The optical transmission fiber with this segmented core profile provides a high effective area, low non-linearity coefficient, nonzero dispersion, and relatively flat dispersion slope.

Abstract: Method for winding a fiber element onto a support. The fiber element having at least two longitudinal portions (Pi) with different characteristics. The method including the steps of supplying the fiber element to the support and associating with each longitudinal portion a respective value of the winding pitch (pi) which is different from the values associated with the portions adjacent thereto. The winding pitch associated with each portion being modulated in accordance with a periodic function.

Abstract: 1

Abstract: A process for producing a high-purity optical silica preform, comprising (a) vaporization of an organosilicon compound; (b) thermal decomposition of the said organosilicon compound in the vapor state, to give amorphous fused silica particles; (c) deposition of the said amorphous fused silica particles on a support, in which the said organosilicon compound has the formula (I) in which R1, R2, R3 and R4 have the meanings given in the text.

Abstract: An optical transmission fiber has a refractive index profile with an area of increased index of refraction at the inner core of the fiber, an annular region positioned radially outward from the inner core with an index of refraction exceeding the index of the inner core, and at least a low dopant content region in a cross-sectional region between the inner core and the annular region. A low loss cladding layer surrounds the core region. The optical transmission fiber with this segmented core profile provides a high effective area, low non-linearity coefficient, nonzero dispersion, and relatively flat dispersion slope.

Abstract: Optical fiber tensioning device, receiving at its input an optical fiber (35) from a traction device (37) and capable of supplying the optical fiber from its output to a device (40) for storing the fiber. The tensioning device (1) comprises at least one fixed pulley (32) on which the optical fiber (35) is wound, for a certain length at least, and at least one movable pulley (9) on which the optical fiber (35) is wound, for a certain length at least. A device for measuring the tension applied to the fiber and a motorized device (24, 26, 5, 7) for moving the movable pulley (9) interact with each other to control the distance (Dp) between the axes (33, 20) of the pulleys (32, 9) in such a way as to automatically keep the tension applied to the fiber essentially constant.

Abstract: A method for manufacturing an optical fiber (100) having low PMD, comprises the steps of:

Abstract: The present invention relates to an optical amplifier and a telecommunication system including a plurality of the optical amplifiers connected in cascade, particularly adapted for a wavelength division multiplexing transmission, in which a combination of dopants in the active fiber core of the optical amplifiers enables a high signal/noise ratio to be achieved for all channels in a predetermined wavelength band, even in the presence of several simultaneously fed signals.

Abstract: The present invention relates to an optical amplifier and a telecommunication system including a plurality of the optical amplifiers connected in cascade, particularly adapted for a wavelength division multiplexing transmission, in which a combination of dopants in the active fiber core of the optical amplifiers enables a high signal/noise ratio to be achieved for all channels in a predetermined wavelength band, even in the presence of several simultaneously fed signals.