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 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 an optical fibre mainly consisting of silica glass, which fibre comprises: i) an inner core having a first refractive index n1 and a first diameter a; ii) an outer core surrounding the outer circumference of the inner core and having a second refractive index n2 and a second diameter b; and iii) a cladding surrounding the outer circumference of the outer core, which cladding has a third refractive index n3, wherein n1>n2>n3.

Abstract: A method of manufacturing an optical fiber and related devices using an apparatus having an elongated microwave guide coupled to a resonant cavity formed of an outer cylindrical wall and inner cylindrical wall having a slit with a width W and configured to deliver microwave energy having a vacuum wavelength ? to a resonant cavity thereof to satisfy the relationship: W??/10 where a substrate tube is located within the resonant cavity and plasma chemical vapor deposition deposits layers of doped silica thereon followed by thermal collapsing the substrate and drawing an optical fiber therefrom.

Abstract: A method for depositing one or more glass layers on the external surface of a rod-like glass preform. The method: i) places the preform in an enclosed space, ii) creates a sub-atmospheric pressure in the enclosed space, iii) supplies one or more reactive gases, which may or may not be doped, to the enclosed space, iv) generates a plasma zone in the enclosed space, and v) carries out a deposition reaction.

Abstract: A method of manufacturing an optical fiber and related devices using an apparatus having an elongated microwave guide coupled to a resonant cavity formed of an outer cylindrical wall and inner cylindrical wall having a slit with a width W and configured to deliver microwave energy having a vacuum wavelength &lgr; to a resonant cavity thereof to satisfy the relationship: W≦&lgr;/10 where a substrate tube is located within the resonant cavity and plasma chemical vapor deposition deposits layers of doped silica thereon followed by thermal collapsing the substrate and drawing an optical fiber therefrom.

Abstract: The invention relates to an apparatus for performing Plasma Chemical Vapor Deposition (PCVD), whereby one or more layers of silica can be deposited on an elongated vitreous substrate. The apparatus includes an elongated microwave guide which emerges into a resonant cavity which is substantially cylindrically symmetric about a cylindrical axis, along which axis the substrate can be positioned. Aspects of the apparatus include the cavity being substantially annular in form, with an inner cylindrical wall and an outer cylindrical wall and the inner cylindrical wall having a slit which extends in a full circle around the cylindrical axis: Additional aspects include the guide having a longitudinal axis which is substantially perpendicular to the cylindrical axis and which does not intercept the slit. The invention also relates to a method of manufacturing an optical fiber, a preform rod and a jacket tube as well as to the thus obtained optical fiber.

Abstract: The invention relates to a device for applying, in use, electromagnetic microwave radiation in a plasma cavity, which plasma cavity is present within a housing, being substantially cylindrically symmetric about a (first axis, and which comprises a cylindrical wall provided with a circumferential slit, said plasma cavity being in communication, via said slit, with a first end of an elongated microwave guide having a longitudinally extending second axis, said device being in communication in use with microwave generating means via the other end of said microwave guide, in which the electromagnetic microwave radiation being generated may comprise several modes.

Abstract: The invention relates to an apparatus for performing Plasma Chemical Vapor Deposition (PCVD), whereby one or more layers of silica can be deposited on an elongated vitreous substrate. The apparatus includes an elongated microwave guide which emerges into a resonant cavity which is substantially cylindrically symmetric about a cylindrical axis, along which axis the substrate can be positioned. Aspects of the apparatus include the cavity being substantially annular in form, with an inner cylindrical wall and an outer cylindrical wall and the inner cylindrical wall having a slit which extends in a full circle around the cylindrical axis: Additional aspects include the guide having a longitudinal axis which is substantially perpendicular to the cylindrical axis and which does not intercept the slit. The invention also relates to a method of manufacturing an optical fiber, a preform rod and a jacket tube as well as to the thus obtained optical fiber.

Abstract: The present invention relates to an optical fibre mainly consisting of silica glass, which fibre comprises:

Abstract: The invention relates to an apparatus for performing Plasma Chemical Vapor Deposition (PCVD), whereby one or more layers of silica can be deposited on an elongated vitreous substrate, the apparatus comprising an elongated microwave guide which emerges into a resonant cavity which is substantially cylindrically symmetric about a cylindrical axis, along which axis the substrate can be positioned, in which apparatus: the cavity is substantially annular in form, with an inner cylindrical wall and an outer cylindrical wall; the inner cylindrical wall comprises a slit which extends in a full circle around the cylindrical axis; the guide has a longitudinal axis which is substantially perpendicular to the cylindrical axis and which does not intercept the slit. The invention also relates to a method of manufacturing an optical fiber, a preform rod and a jacket tube using said apparatus as well as to the thus obtained optical fiber.

Abstract: The invention relates to an apparatus for performing Plasma Chemical Vapor Deposition (PCVD), whereby one or more layers of silica can be deposited on an elongated vitreous substrate, the apparatus comprising an elongated microwave guide which emerges into a resonant cavity which is substantially cylindrically symmetric about a cylindrical axis, along which axis the substrate can be positioned, in which apparatus:

Abstract: The invention relates to an apparatus for performing Plasma Chemical Vapor Deposition (PCVD), whereby one or more layers of silica can be deposited on an elongated vitreous substrate, the apparatus comprising an elongated microwave guide which emerges into a resonant cavity which is substantially cylindrically symmetric about a cylindrical axis, along which axis the substrate can be positioned, in which apparatus: the cavity is substantially annular in form, with an inner cylindrical wall and an outer cylindrical wall; the inner cylindrical wall comprises a slit which extends in a full circle around the cylindrical axis; the guide has a longitudinal axis which is substantially perpendicular to the cylindrical axis and which does not intercept the slit. The invention also relates to a method of manufacturing an optical fiber, a preform rod and a jacket tube using said apparatus as well as to the thus obtained optical fiber.