Abstract: A method for reducing the hydrogen aging loss of silica optical fibers by irreversible reaction of the peroxide defects with deuterium is described. This method comprises the step of contacting the optical fiber with deuterium by exposure to a gas mixture containing deuterium at a temperature compatible with the fiber without exposing the fiber to any further activation, and subsequently the step of degassing the fiber in a neutral atmosphere. The invention relates further to a process of producing optical fibers with low hydrogen aging loss wherein an optical fiber is treated using the method for reducing the hydrogen aging loss. Finally, the invention relates to optical fibers with low hydrogen aging loss obtainable by this process and telecommunication cables produced using these optical fibers. Using the new method, an activation step using intense light and/or elevated temperature is not necessary to achieve the reaction of peroxide defects in silica with deuterium.

Abstract: A method for reducing the hydrogen aging loss of silica optical fibers by irreversible reaction of the peroxide defects with deuterium is described.

Abstract: A coating die that includes an insert having a high thermal conductivity, which is greater than 1 W/cm*K. Preferably, the insert is made of diamond having a thermal conductivity in the range of 5 to 20 W/cm*K. Use of this highly conductive insert helps to efficiently dissipate the heat produced by viscous losses in the coating as most of these losses occur very close to the inner wall of the die in the land region. It also reduces to negligible level the wall temperature unbalance between opposite sides of the fiber when this fiber is off-centered thus restoring conditions prevailing at low draw rates and subsequent satisfactory centering force.

Abstract: The invention relates to a method of determining at least one characteristic of an optical fiber with the aid of a reflectometer, in which method the fiber to be characterized is connected at both ends to reference fibers and a reflectometer measurement is performed for each reference fiber. To determine if reflectometer data relating to the fiber to be characterized obtained after the two measurements is correct, reflectometer data corresponding to two equivalent points of the reference fibers is compared. The reflectometer data of the fiber to be characterized is retained only if the difference between the data compared is the same for both measurements. The reflectometer data compared for the two reference fibers consists of mean values for equivalent segments, for example.