Abstract: The disclosed Plasma Chemical Vapor Deposition (PCVD) process uses the injection of plasma-reactive gas to control deposition oscillation and refractive-index oscillation (e.g., alpha oscillation). This PCVD process, which may employ a modified PCVD apparatus, achieves more uniform glass deposition. This, in turn, results in optical preforms and optical fibers having more uniform optical properties.

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 an optical preform via an internal vapor deposition process, wherein during the inside deposition process the velocity of the reaction zone is set so that the velocity of the reaction zone over the length of the supply side-to-discharge side is higher than the velocity of the reaction zone over the length of the discharge side-to-supply side.

Abstract: A method for manufacturing a primary preform including providing a hollow substrate tube, supplying to the interior of the tube a main gas flow containing at least one glass-forming gas and at least one secondary gas flow containing at least one precursor for a dopant, creating a plasma reaction zone in the interior of the tube to effect deposition, and interrupting the supply of the at least one secondary gas flow near the reversal points of the supply and discharge sides of the substrate tube.

Abstract: A method for manufacturing a primary preform for an optical fiber wherein conditions are created in the reaction zone such that one or more glass layer packages made up of at least two separate glass layers are deposited on the interior of the substrate tube.

Abstract: A device for applying electromagnetic microwave radiation in a plasma inside a substrate tube including inner and outer cylindrical walls defining an annular cavity therebetween, the inner wall having a circumferential applicator slit, an elongate microwave guide arranged with a first end in communication with the annular cavity and a second end in communication with a microwave generating means for supplying microwaves to the annular cavity, and means for supplying a cooling gas through the elongate microwave guide to a position near the applicator slit.

Abstract: A method for manufacturing a primary preform for optical fibers using an internal vapor 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 including surrounding at least part of a hollow substrate tube with a furnace set at a temperature T0, supplying doped or undoped gases to the inside of the tube, creating a reaction zone to promote deposition, and moving the zone back and forth along the length of the tube between to form at least one preform layer, wherein the temperature of the furnace is varied linearly as a function of the thickness of the at least one preform layer to compensate for temperature increases of the tube during deposition.

Abstract: A method for activating an inner surface of a hollow glass substrate tube for manufacturing an optical fiber preform including depositing a plurality of activation glass layers on the inner surface of the hollow substrate tube by a PCVD process, wherein a total thickness of the deposited activation glass layers is between 10 microns and 250 microns, and etching the deposited activation glass layers to remove at least 30% of the deposited activation glass layers.

Abstract: A method for manufacturing a primary preform for optical fibers using an internal vapor 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 method for manufacturing a primary preform for optical fibers, using an internal vapor deposition process, wherein a gas flow of doped undoped glass-forming gases is supplied to the interior of a hollow substrate tube having a supply side and a discharge side via the supply side thereof, wherein deposition of glass layers on the interior of the substrate tube is effected as a result of the presence of a reaction zone.

Abstract: The present invention relates to an apparatus for carrying out plasma chemical vapor 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 vapor 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 vapor 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: A method for manufacturing a primary preform for optical fibers using an internal vapor 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: A method for manufacturing a primary preform for optical fibers using an internal vapor 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 device for contracting a hollow substrate tube made of quartz glass into an optical perform including a heat source movable relative to the longitudinal direction of the substrate tube and an insert tube positioned in the interior of the substrate tube, at one end thereof, provided with a central opening through which a gas is passed and supplied to the interior of the substrate tube.

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 for manufacturing an optical preform via an internal vapour deposition process, wherein during the inside deposition process the velocity of the reaction zone is set so that the velocity of the reaction zone over the length of the supply side-to-discharge side is higher than the velocity of the reaction zone over the length of the discharge side-to-supply side.

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 primary preform for optical fibres, using an internal vapour deposition process, wherein a gas flow of doped undoped glass-forming gases is supplied to the interior of a hollow substrate tube having a supply side and a discharge side via the supply side thereof, wherein deposition of glass layers on the interior of the substrate tube is effected as a result of the presence of a reaction zone.