Optical fiber sensor and a manufacturing process for making same
AssigneeThomson-CSF
InventorsMarc Turpin, Marie-Noelle Charasse, Jean-Pierre Le Pesant
Life of this patent
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Abstract
The invention is a hollow fiber with, over the full length of the fiber and between each fiber channel (3, 4) and the core, at least one stress zone (5, 6) to create an anisotropic stress distribution which subjects the fiber core to a tensile stress. The cable design is advantageous in that it is possible to control the sign of the fiber intrinsic birefringence. The cable is thus advantageous for use as a pressure sensor or pressure transducer.
Claims16
A sensor formed of an optical fiber comprising a guide core enclosed in guide cladding with a refractive index which is lower in the core of the cladding and which includes, close to the core, at least one cavity, running the full length of the fiber, and which also includes, over the full length of the fiber, between said at least one cavity and the fiber core, a stress zone which creates an anisotropic stress distribution and generates a tensile stress in the fiber core, and wherein said stress zone is disposed in said guide cladding.
A sensor formed of an optical fiber comprising a guide core in guide cladding with a lower refractive index at the core of the cladding and including, close to the core and over the full fiber length, at least one cavity lying on a first plane of symmetry through the fiber centerline, in which there is also, over the full length of the fiber and in a second plane of symmetry, perpendicular to the first plane, at least one stress zone creating an anisotropic stress distribution and generating a compressive stress in the fiber core, and wherein said at least one stress zone is disposed in said guide cladding such that said at least one stress zone and said at least one cavity are separated by said guide cladding.
A process to manufacture an optical fiber in which a blank, comprising guide cladding surrounding guide core and enclosed in a buffer, is manufactured first and in which two grooves, located on either side of the core, are machined in the blank;
- strips of material different to the guide cladding are then placed in each groove and each strip is covered by a plate in identical material to the buffer, the assembly is placed in a tube in material similar to that of the buffer so that an empty space exists between each plate and the tube;
- this blank is then drawn.
A process to manufacture an optical fiber in which a blank, comprising guide cladding surrounding a guide core and enclosed in a buffer is manufactured first and in which two longitudinal grooves, located on a first plane of symmetry through the fiber centerline and symmetrical about the fiber axis of symmetry, are machined together with two grooves located on a second plane of symmetry, perpendicular to the first plane and symmetrical about the fiber axis of symmetry;
- the two grooves are then filled with a stress material after which the assembly is placed in a tube and, finally, drawn.
Dependencies are inferred from the claim text.