Abstract: The invention relates to an optical fiber presenting a core, cladding, and a grating written by irradiation and coupling at least one light mode into the cladding so that it is dissipated therein. The invention proposes causing the mean index to vary progressively along the grating, at least at the ends of the grating. The progressive variation in mean index or in the amplitude of index modulation for writing the grating serves to limit insertion losses to the filter formed by the grating. Analogously, in a written-in grating, the invention provides the equivalent of progressively varying the core size of the fiber for interconnecting two optical fibers presenting different core diameters. The invention is applicable in particular to gain-equalizing filters in WDM transmission systems.

Abstract: The invention relates to an optical fiber presenting a core, cladding, and a grating written by irradiation and coupling at least one light mode into the cladding so that it is dissipated therein. The invention proposes causing the mean index to vary progressively along the grating, at least at the ends of the grating. The progressive variation in mean index or in the amplitude of index modulation for writing the grating serves to limit insertion losses to the filter formed by the grating. Analogously, in a written-in grating, the invention provides the equivalent of progressively varying the core size of the fiber for interconnecting two optical fibers presenting different core diameters. The invention is applicable in particular to gain-equalizing filters in WDM transmission systems.

Abstract: The present invention relates to a method of coupling a multi-core optical fiber to a plurality of single-core optical fibers, the multi-core optical fiber comprising N mutually parallel optical cores (N.gtoreq.4) embedded in common optical cladding, and each of the single-core optical fibers comprising one optical core surrounded by optical cladding. In this method, the coupling is distributed over P coupling levels (2.ltoreq.P<N), each coupling level including at least two single-core optical fibers. The coupling levels are offset longitudinally relative to one another along said multi-core optical fiber, and are such that each of said fibers belonging to the coupling levels is disposed parallel to and facing a core of the multi-core fiber, and is secured to the optical cladding of the multi-core fiber so as to obtain lateral evanescent-wave coupling.

Abstract: The optical sensor includes a support (2), an optical fiber (15) and two elements (9, 10) mounted on the support (2) in such a manner as to move as a function of the variations of a quantity to be measured, such as pressure. The attenuation of an optical radiation in the optical fiber (15) deformed by reverse bending is measured. The support (2) is constructed in the form of a bending beam including two end parts (2b, 2c) bearing on two fixed abutments and a central part (2a) connected to a metal membrane (16) actuated as a function of the variations of the quantity to be measured. The optical fiber (15) is disposed between the two movable elements (9, 10) in the form of a comb, each fixed on an end part (2b, 2c) of the support. The elements (9, 10) include active surfaces coming into contact with the fiber (15) to produce a variable reverse bending of the fiber (15) in the course of their relative movement.

Abstract: Twenty temperature sensors follow one another along a measurement fiber. Each successively reflects a small fraction of the energy of an interrogation light pulse running along said fiber, with the value of the fraction being indicative of temperature. To do this, each sensor is constitutred by a gap between two successive lengths (F2, F3) of an optical fiber, said gap being filled with a transparent glue (36) whose refractive index varies as a fuction of temperature. The interrogation pulse is returned solely by the optical surface constituted by the end face (38) of the upstream length (F2) of the fiber.

Abstract: An optical source comprises a base on which a light-emitting component is mounted. A fiber-carrier in the form of a slab is fastened to the base. An optical fiber mounted on the fiber-carrier has an end optically coupled to the light-emitting component. An intermediary part in the form of a narrow slab with plane surfaces is attached to the base. The fiber-carrier is spot soldered to the intermediary part using an electrical resistance soldering process.

Abstract: An automatic machine for welding optical fibers end-to-end comprises a first plate (1) for supporting a first or "reference" fiber (2) and a second plate (5) for supporting a second or "moving" fiber (6). The second plate can be translated along Ox and Oy axes in a plane perpendicular to the axes of the fibers. The ends of the fibers are illuminated by light sources (30, 31), optical systems make images thereof, and optical pick-ups (12, 13, 18, 19) located at the image points provide optical signals representative of the positions of the optical fibers relative to each of said Ox and Oy axes. These signals are converted into electrical signals and are compared by electronic comparators (15, 21) which deliver corresponding error signals to control means (17, 23, 24) for moving the second plate until the moving fiber is in alignment with the reference fiber.

Abstract: Fibre-retaining grooves are formed in-between a set of fibre locating pins (M) laid side by side. The pins and a base plane (4) on which they are laid are made of hard, rigid material. Guidance for connection and disconnection is provided by guide pins (G1 to G4) of larger diameter which are therefore robust enough to stand up to handling. The guide pins are in direct contact with the locating pins in order to ensure positional accuracy.