France Telecom

France Telecom Etablissement Autonome De Droit Public

French State Represented by the Minister of Post, Telecommunications and

Sa Highwave Optical Technologies

Get/enst Betagne

Groupe Des Ecoles Des Telecommunications/ Ecole Nationale Superieure De Telecommunications De Bretagne

Philippe Grosso

Georges E Le Noane

Daniel Boscher

Jean-Louis De Bougrenet De La Tocnaye

Isabelle Hardy

David Mechin

Zong Yan Wu

Jean-Louis De Dougrenet De La Tocnaye

Marc Le Menn

Michel Nolf

An optical refractometer is provided for measuring the refractive index of a liquid. Such a refractometer includes a first optical block having a transparent material whereto is secured a light source, a second optical block having a transparent material whereto is secured a position sensor. The optical blocks are arranged on either side of a conduit wherein the liquid flows.

Optical refractometer for measuring seawater salinity and corresponding salinity sensor

The invention provides a method of photoinducing a Bragg grating in an optical fiber () or a waveguide, in which a selected zone of the fiber () or waveguide is subjected to a step of being exposed with a source beam () using a mirror () in such a manner as to fold a portion () of the source beam () as reflected by the mirror () onto a portion () of the source beam that is not reflected by the mirror, thereby obtaining a diffraction grating in the fiber () or waveguide, the method being characterized in that an additional exposure step is performed on said portion of the fiber () or waveguide, and in that relative displacement is imparted between the two exposure steps to elements selected from the beam (), the fiber () or waveguide, and the mirror () in such a manner as to cause a same portion of the beam () used for photoinduction in both exposure steps to be reflected by the mirror () in one of the steps and not reflected by the mirror () in the other step.

Apodization method for a bragg grating

The invention relates to an exposure method for producing a Bragg grating on a photosensitive guide ( ) or optical fiber ( ), in which method the guide (the fiber) ( ) is scanned by a light beam ( ) and means ( ) are provided for modulating the exposure time along the guide (the fiber) by varying the speed at which the beam ( ) moves along the guide (the fiber) ( ) so that it is located opposite each location of the guide (the fiber) ( ) for a time period that varies with the location, the method including the step of disposing in front of the guide (the fiber) ( ) a system ( ) adapted to create interference fringes on the guide (the fiber) ( ) and to scan the beam ( ) over the interference system ( ) at a speed that is modulated along the system ( ), and furthermore the step of having the beam scan the guide (the fiber) ( ) at a modulated speed without the interference system ( ) on the path of the beam ( ), the scanning with the interference system ( ) being effected with modulation of the exposure time increasing the exposure time in the central part of the guide (the fiber) ( ) and the scanning without the interference system being effected with modulation of the exposure time reducing the exposure time in the central part of the guide (the fiber) ( ).

Photowritten Bragg grating apodization method

Process for making preforms for multicore optical fibers. According to this process, several elementary preforms are made, a first machining is performed on them such that a chosen geometric model will be obtained after they are assembled, a second machining is performed such that the assembly (11) has at least one hole (12), the preforms are assembled and an induction furnace (18) is used to fuse the preforms, while creating a vacuum in each hole.

Process for making preforms for multicore optical fibers

Small, high precision, multicore optical guides and process for the production of said guides. Such a guide includes elementary guides (G1 to G4) and a matrix (M) in which they are located. These elementary guides are very accurately positioned with respect to one another in the matrix and with respect to the external contours (5) thereof and have high precision geometrical characteristics. According to the process, manufacturing and machining of the blanks so as to obtain, after assembly, the chosen geometrical model for the multicore guide. They are assembled in accordance with this model, welded together by means of a bait and the assembly is drawn.

Small, high precision, multicore optical guides and process for the

A device for measuring the diameter of an object that is generally cylindrical such as, for example, an optical fiber, without contact. This device includes a laser (4) capable of emitting a luminous beam, optical means (6, 8, 10) provided to form first and second luminous beams from the luminous beams emitted by the laser and to illuminate the object (2) with these first and second luminous beams, so as to obtain two luminous beams reflected by the object which interfere with one another, and means (CCD, 14) of photo-detection and analysis of the interference between the two reflected beams, capable of determining the diameter of the object from the interference fringes.

Device for measuring the diameter of an object that is largely

Method and device for the geometric characterization of transparent tubes. According to the invention, in order to characterize a transparent tube whose internal and external walls are approximately cylindrical and coaxial, the tube is placed in the air and scanned by an incident luminous beam moved parallel to it within a section plane perpendicular to the axis of the tube. Beams (F0, F1, F2, F3, F4) not deflected by the tube are detected. The detected beams, except for one which passes through the axis of the tube form two pairs. The distance between the two beams of each of these two pairs is determined, and, with the aid of these distances, the internal and external diameters of the tube at the level of the cutting plane are determined. Application for the geometric characterization of tubes for preforms for optical fibers.

Growing community of inventors

Lannion, France

Philippe Grosso