Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: A method for manufacturing a preform for optical fibers by a vapor deposition process wherein an intermediate step is carried out between one deposition phase and the next deposition phase(s), wherein the intermediate step includes supplying an etching gas to the supply side of the hollow substrate tube.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibers via a vapor deposition process in which the position of the reversal point near the substrate tube's supply side shifts along the longitudinal axis of the substrate tube during at least part of the deposition process.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: A method for manufacturing a preform for optical fibers by means of a vapor deposition process, wherein plasma conditions are created and wherein the plasma is moved back and forth along the longitudinal axis of the hollow substrate tube between a reversal point near the supply side and a reversal point near the discharge side of the hollow substrate tube, so that the location where the soot deposition associated with one phase takes place is axially spaced from the location where the soot deposition associated with the other phase(s) takes place.

Abstract: The present invention relates to an apparatus for carrying out a PCVD deposition process, wherein one or more doped or undoped layers are coated onto the interior of a glass substrate tube, which apparatus comprises an applicator having an inner and an outer wall and a microwave guide which opens into the applicator, which applicator extends around a cylindrical axis and which is provided with a passage adjacent to the inner wall, through which the microwaves can exit, over which cylindrical axis the substrate tube can be positioned, and wherein at least one choke of annular shape having a length l and a width w is centred around the cylindrical axis within the applicator.

Abstract: The present invention relates to an apparatus for carrying out a plasma chemical vapor deposition process by which one or more layers of doped or undoped silica can be deposited on the interior of an elongated glass substrate tube. The present invention further relates to a method for manufacturing an optical fiber using such an apparatus.

Abstract: A method for manufacturing a preform for optical fibers by means of a vapour deposition process, wherein plasma conditions are created and wherein the plasma is moved back and forth along the longitudinal axis of the hollow substrate tube between a reversal point near the supply side and a reversal point near the discharge side of the hollow substrate tube, so that the location where the soot deposition associated with one phase takes place is axially spaced from the location where the soot deposition associated with the other phase(s) takes place.

Abstract: A preform for manufacturing an optical fibre or an optical fiber, where the variation in the refractive index contrast of the preform does not exceed an absolute value of 2%, measured for a preform having a length of at least 60 cm, or the deviation of the preform in relation to the average value of the profile parameter ? does not exceed an absolute value of 0.03, measured for a preform having a length of at least 80 cm. The optical fibre has a deviation from the average value of the profile shape parameter ? of maximally about 0.03.

Abstract: The present invention relates to a method for manufacturing an optical preform by employing an internal vapor deposition process. The method uses an energy source and a substrate tube, wherein the energy source is movable over the length of the substrate tube between a point of a reversal at the supply side and a point of a reversal at the discharge side.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibres by means of a vapour deposition process, wherein plasma conditions are created, and wherein the plasma is moved back and forth along the longitudinal axis of the hollow substrate tube between a reversal point near the supply side and a reversal point near the discharge side of the hollow substrate tube, wherein a transition deposition is carried out between the deposition of one phase and the deposition of the other phase.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibres by means of a vapour deposition process, wherein an intermediate step is carried out between one deposition phase and the next deposition phase(s), wherein the intermediate step comprises supplying an etching gas to the supply side of the hollow substrate tube.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibers via a vapor deposition process in which the position of the reversal point near the substrate tube's supply side shifts along the longitudinal axis of the substrate tube during at least part of the deposition process.

Abstract: The present invention relates to a method for manufacturing an optical preform by carrying out one or more chemical vapor deposition reactions in a substrate tube. The method includes the steps of (i) supplying one or more doped or undoped glass-forming precursors to a substrate tube and (ii) effecting a reaction between these glass-forming precursors to form one or more glass layers on the interior of the substrate tube via the creation of a pulsed plasma zone in the interior of the substrate tube.

Abstract: The present invention relates to a method for manufacturing an optical preform by employing an internal vapor deposition process. The method uses an energy source and a substrate tube, wherein the energy source is movable over the length of the substrate tube between a point of a reversal at the supply side and a point of a reversal at the discharge side.

Abstract: The present invention relates to a method of manufacturing an optical fiber, which method comprises the following steps: i) providing a hollow substrate tube, ii) passing doped or undoped reactive, glass-forming gases through the interior of the hollow substrate tube, iii) creating such conditions in the interior of the hollow substrate tube that deposition of glass layers onto the interior of the hollow substrate tube takes place, wherein a non-isothermal plasma is reciprocated between two reversal points along the substrate tube, wherein the velocity of movement of the plasma decreases to zero at each reversal point, iv) collapsing the substrate tube thus obtained so as to form a solid preform, and v) drawing an optical fiber from said solid preform. In addition to that, the present invention relates to a preform for manufacturing an optical fiber, as well as to an optical fiber.