Abstract: The present invention concerns an optical fiber cable containing a plurality of optical fibers split up into modules, each module being covered with a supporting sheath in contact with the outer optical fibers of the module so as to hold the optical fibers contained in said module tightly so that they are mechanically coupled to one another, the entire set of modules being disposed inside a covering made of an insulating material, which covering is in contact with the outer modules of the set of modules so as to form a compact assembly comprising all of the modules;wherein each optical fiber has a cut-off wavelength of not more than 1,350 nm, and, at a wavelength in the vicinity of 1,550 nm, has a mode field diameter lying in the range 7 .mu.m to 9 .mu.m, and wherein each optical fiber is provided with a substantially hermetic coating on its optical cladding.

Abstract: The present invention relates to an optical fiber cable, in particular for a distribution network, and comprising an assembly of optical fibers, wherein each of the optical fibers has a mode field diameter lying in the range 7 .mu.m to 9 .mu.m at around 1550 nm, and a cutoff wavelength less than or equal to 1.35 .mu.m, and wherein the optical fibers are assembled together in the cable by being twisted around one another or around a reinforcing element, or by being disposed lengthwise.

Abstract: The present invention relates to an optical fiber comprising an optical core surrounded by optical cladding, said optical cladding being surrounded by a substantially hermetic coating, wherein said optical fiber has a mode field diameter lying in the range 7 .mu.m to 9 .mu.m at around 1550 nm, and a cutoff wavelength that is less than or equal to 1.35 .mu.m.

Abstract: A device for connecting on site two optical fiber transmission cables comprises a table for installation in a cable tunnel on the site and which is provided with a notch on its circumference, a tight box which bears against the table and whereof the two lateral faces have two openings in which are engaged the two cables to be connected, a splicing bench positioned in the table notch and on which are arranged tools for splicing the two cables, and means for joining the bench to the table.

Abstract: A transmission cable using optical fibre for conveying the information consists of fibres loosely laid in helical grooves of a core so that the fibre will undulate within the groove due to over-length given by pretwisting of the fibre and curvature of the groove flanks. Reduction of the contact surface between the fibre and the core improves the electrical characteristics and reduces the sensitivity of the cable to mechanical stress.

Abstract: A process and tooling to carry on said process for producing direct from extrusion an open groove plastic cylindrical section which consists in extruding the material around cylindrical pins arranged along a circle and protruding downstream with respect with the die opening and drawing the deformable structure along inner cutters located in the ducts formed by the pins to cut the material between the duct and the outside and further drawing said still deformable structure around flexible wires free to fill said slitted ducts.

Abstract: The electro-optic converter is designed to terminate optical fiber cables consisting of a mechanical core surrounded by a helically grooved sheath in which an optical fibre is loosely placed in the grooves. It consists of an hybrid circuit conversion matrix made of a substrate with a central bore cooperating with a bore in a standard multi-pin casing base for positioning the cable core; a star shaped conductive film on said substrate serves as a common electrode for the plurality of discrete opto-electronic devices also connected each to a different pin of the base and in centering and locking means for the cable.

Abstract: A head for laying optical fibres in a helically grooved cable core consists of a freely rotating mount assembly carrying fibre guides inclined on the axis of travel of the core with an angle smaller than 45.degree.. The fibre guides are elastic hollow tubes ended by a bevel maintained on the bottom of the associated groove. An optical control unit is provided for correct positioning of the mount when starting to lay.

Abstract: Continuous machining of grooves in a cylindrical dielectric rod is achieved by guiding the rod into a heating machining head incorporating a rotating cutter made from a chemically etched stainless steel sheet and guiding the rod downstream of said head. A chip removing head made of a rotating unit comprising channels in which said chips are aspired by decompression effect of a gas is mechanically coupled with and upstream of the machining head.

Abstract: An extrusion tool consisting of a stack of thin metal wafers in which apertures have been machined by chemical etching. Each wafer has one or several apertures. For simple profiles the wafers are identical. The apertures in adjacent wafers are angularly offset one with respect of the other for helical extrusion.

Abstract: A cable comprising a central armour, a dielectric helically grooved core and an optical fibre housed in each one of the plurality of the grooves is produced by extrusion of the profiled core on the armour, pulling vertically the core through an annular laying unit comprising a plurality of take off reels supplying optical fibre guiding each of said fibre within one of the grooves by mechanical and pneumatic means and taping fibre filled core.

Abstract: A cable comprising a central armour, a dielectric helically grooved core and optical fibres housed in said grooves which are formed with a lip protruding from one edge is produced by extrusion of the profiled core on the armour heating of the core, laying of one fibre within one groove with the aid of a fibre guide controlled by a positioning slot in said core, bending the lip to close the groove outwardly and repeating said heating, laying, etc. . . for each fibre and taping the structure.

Abstract: In a microwave cylindrical heating TM.sub.010 cavity for continuous heating of rods, wires, etc. . . focussing means are provided surrounding the entry and or the exit to locally concentrate the microwave energy on the object to be heated. Said means consists in 45.degree. annular wedge. As variants focussing is achieved by ferromagnetic annulus.

Abstract: A broadband slot line non reciprocal microwave device which comprises a matched load placed on the face of a ferrite plate which is located within the microwave magnetic field of the slot line, said face being opposite to said slot and designed so that its height is larger than 3 times the width of the slot and its length is at least equal to a half wavelength as propagated within the slot at the maximum operating frequency. Said matched load may be a second slot line or a lossy ferrite plate. The device operates as an isolator with more than 20 dB isolation. It can be designed as a four port circulator.