Draka Comteq B.v.

Emmanuel Petitfrere

Pierre Sillard

Denis Molin

Louis-Anne De Montmorillon

Pascale Nouchi

Marianne Bigot-Astruc

Bob J Overton

Yves Lumineau

Simon Richard

Pieter Matthijsse

Frans Gooijer

Franciscus Johannes Achten

Cedric Gonnet

Ivo Flammer

David Boivin

Laurent Calvo

Gaetan Cuvelier

Cédric Gonnet

Laurent Jardy

Olivier Delwal

The invention relates to an optical fiber preform () comprising a primary preform () and one or more purified silica-based overclad layers () surrounding said primary preform (), the purified silica-based overclad layers () comprising lithium and aluminium, and having a ratio between lithium concentration [Li] and aluminium concentration [Al] satisfying the following inequality:1&#xd7;10&#x2264;[Li]/[Al]&#x2264;20&#xd7;10.

Optical fiber preform and method for manufacturing such optical fiber preform from a primary preform

The invention relates to a method for welding one end of a primary preform and one end of a silica bar having different properties. The method includes the steps of projecting and fusing silica grain under a plasma torch onto an end of the primary preform and an end of the silica bar, and bringing into contact these respective ends to form an excellent weld between the primary preform and the silica bar. The invention provides a cost-effective way to secure a primary preform to a glass-working lathe support while reducing the risk of costly preform breakage.

Method for forming an improved weld between a primary preform and a silica bar

Method for overcladding an optical fiber preform with a given target diameter (D) of the final preform includes providing a primary preform to be overcladded, and successively depositing first overcladding layers by projecting and vitrifying silica particles on the primary preform moving in relative translation with a plasma torch. Each first overcladding layer has a given uniform thickness (d) and is deposited at a given, constant silica particle flow rate and at a given, constant translation speed. The method also includes the detection of a preform diameter (D) greater than a given threshold (S) and the deposition of a final overcladding layer having the remaining required thickness (D&#x2212;D) at a constant silica particle flow rate and at a reduced translation speed. The inventive method enables a preform to be overcladded efficiently with improved yield and high quality.

Method for overcladding an optical fiber preform

Disclosed is an optical transmission fiber having reduced bending and microbending losses that is commercially usable in FTTH or FTTC transmission systems.

Single-mode optical fiber

The invention relates to a method for manufacturing a final optical fiber preform by overcladding, said method comprising the steps of providing a primary preform; positioning said primary preform within at least one tube, wherein the at least one tube partly covers the primary preform to create a zone to be overcladded, being an overclad zone, which overclad zone is located on the primary preform outside the at least one tube; injecting a gas into the annular space between the primary preform and the at least one tube under overpressure relative to the pressure outside the at least one tube; overcladding the primary preform in the overclad zone with an overcladding material using an overcladding device. The invention also relates to an apparatus for carrying out the method. The invention allows overcladding a primary preform at low cost while maximally limiting the incorporation of impurities into the silica overclad.

Method and apparatus for manufacturing low OH overcladding

Disclosed is a plasma torch for overcladding a primary preform of an optical fiber. The plasma torch includes a confinement tube for confining an induced plasma and a torch base. The torch base has a ceramic surface internal to the confinement tube. The plasma torch has extended life even at high input powers.

Plasma torch for overcladding an optical fiber preform

Growing community of inventors

Villeneuve d'Ascq, France

Emmanuel Petitfrere