Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process, including the steps of: i) providing a hollow glass substrate tube having a supply side and a discharge side, ii) surrounding at least part of the hollow glass substrate tube by a furnace, iii) supplying doped or undoped glass-forming gases to the interior of the hollow glass substrate tube via the supply side thereof, iv) creating a reaction zone in which conditions such that deposition of glass will take place on the interior of the hollow glass tube are created, and v) moving the reaction zone back and forth along the length of the hollow glass substrate tube between a reversal point located near the supply side and a reversal point located near the discharge side of the hollow glass substrate tube, wherein, during at least part of step v), the gas flow comprises a first concentration of fluorine-containing compound when the reaction zone is moving in the direction of the discharge side.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process, including the steps of: i) providing a hollow glass substrate tube having a supply side and a discharge side, ii) surrounding at least part of the hollow glass substrate tube by a furnace, iii) supplying a gas flow, doped or undoped, of glass-forming gases to the interior of the hollow glass substrate tube via the supply side thereof, iv) creating a reaction zone in which conditions such that deposition of glass will take place on the interior of the hollow glass tube are created, and v) moving the reaction zone back and forth in longitudinal direction over the hollow glass substrate tube between a reversal point located near the supply side and a reversal point located near the discharge side of the hollow glass substrate tube.

Abstract: The present invention relates to an apparatus for carrying out a PCVD process in which one or more doped or undoped glass layers are coated onto the interior of a glass substrate tube. The apparatus comprises an applicator having an inner wall and an outer wall and a microwave guide that opens into the applicator. The applicator extends around a cylindrical axis and which is provided with a passage adjacent to the inner wall, through which the microwaves supplied via the microwave guide can exit, over which cylindrical axis the substrate tube can be positioned, while the applicator is fully surrounded by a furnace that extends over the cylindrical axis.

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: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace, supplying glass-forming gases to the interior of the tube via the supply side, creating a reaction zone with conditions such that deposition of glass will take place on the inner surface of the tube, and moving the reaction zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form one or more preform layers on the inner surface of the tube, wherein both reversal points are surrounded by the furnace.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace set at a temperature T0, supplying doped or undoped gases via the supply side, creating a reaction zone to promote deposition, and moving the zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form at least one preform layer, which at least one layer comprises several glass layers.

Abstract: The present invention relates to a device for manufacturing an optical preform by means of an internal vapour deposition process, said device comprising an energy source and a substrate tube, which substrate tube comprises a supply side for supplying glass-forming precursors and a discharge side for discharging constituents that have not been deposited on the interior of the substrate tube, said energy source being movable along the length of the substrate tube between a point of reversal at the supply side and a point of reversal at the discharge side.

Abstract: The present invention relates to a device for manufacturing an optical preform by means of an internal vapour deposition process, said device comprising an energy source and a substrate tube, which substrate tube comprises a supply side for supplying glass-forming precursors and a discharge side for discharging constituents that have rot been deposited on the interior of the substrate tube, said energy source being movable along the length of the substrate tube between a point of reversal at the supply side and a point of reversal at the discharge side.

Abstract: A method for manufacturing an optical fiber preform is described that includes detecting structural integrity of the tube during a collapsing phase utilizing a fluid flow that is fed to the tube. Also, a system for manufacturing optical fiber preforms is described that comprises a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, and a fluid supply system configured to supply a fluid to the tube held by the holder. The system comprises a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring the fluid.

Abstract: A method is described for manufacturing an optical fiber preform, including a tube collapsing phase, and including monitoring the concentration of at least one fluid component of a fluid that is exhausted from the tube, to detect structural integrity of the tube. A system is also described for manufacturing optical fiber preforms. The system comprising a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, a fluid exhaust configured to discharge fluid from the tube, held by the holder. The system also includes a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring fluid that is discharged from the tube.

Abstract: Disclosed is a method and device for manufacturing an optical preform. The method includes supplying dopant-containing glass-forming gases to the interior of a hollow glass substrate tube. Furthermore, the supply flow of dopant-containing glass-forming gases includes a main gas flow and one or more secondary gas flows. The secondary gas flows are divided into subflows, which are supplied to the interior of the hollow glass substrate tube together with the main gas flow. The method further includes effecting deposition of glass layers on the interior surface of the hollow glass substrate tube.

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 an apparatus for carrying out a PCVD process in which one or more doped or undoped glass layers are coated onto the interior of a glass substrate tube. The apparatus comprises an applicator having an inner wall and an outer wall and a microwave guide that opens into the applicator. The applicator extends around a cylindrical axis and which is provided with a passage adjacent to the inner wall, through which the microwaves supplied via the microwave guide can exit, over which cylindrical axis the substrate tube can be positioned, while the applicator is fully surrounded by a furnace that extends over the cylindrical axis.

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: The present invention relates to an apparatus for carrying out plasma chemical vapour deposition, by which one or more layers of doped or undoped silica are deposited onto the interior of an elongated hollow glass substrate tube. The present invention further relates to a method of manufacturing an optical preform by means of plasma chemical vapour deposition, wherein doped or undoped glass-forming gases are passed through the interior of an elongated glass substrate tube while conditions for depositing glass layers are created in the interior of the substrate tube.

Abstract: The present invention relates to a device for manufacturing an optical preform by means of an internal vapour deposition process, said device comprising an energy source and a substrate tube, which substrate tube comprises a supply side for supplying glass-forming precursors and a discharge side for discharging constituents that have rot been deposited on the interior of the substrate tube, said energy source being movable along the length of the substrate tube between a point of reversal at the supply side and a point of reversal at the discharge side.

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 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.