Abstract: The present invention relates to a method and an apparatus for fabricating a preform (1,10,100) that can be used for drawing an active optical fiber (8). The present invention further relates to an active optical fiber (8), designed for amplification or attenuation purposes, drawn from said preform (1,10,100) and to an optical amplifier (600, 601) using a laser active optical fiber.

Abstract: The method for fabricating an optical fiber comprises the steps of inserting a primary optical fiber preform (11) having a first primary axis (x1) and an outer surface (111) into an overcladding tube (12) having a second primary axis (x2) and an inner surface (120), so that said outer surface and inner surface define an interior space (15); holding the primary preform (11) in a centrally inserted position within the overcladding tube (12) with said first and second primary axes (x1, x2) in substantial alignment with each other; supplying overcladding grain (13) into the interior space (15) that is limited at the lower end of the overcladding tube (12) by means of a closure (125); generating a condition of reduced pressure within the interior space (15) that is limited at the upper end of the overcladding tube (12) by means of an adjoiner (3), which holds the primary optical fiber preform (11) and the overcladding tube (12) in position; and heating the unprocessed secondary preform (1), that consists of the pr

Abstract: The method for producing and processing a preform comprises a preliminary process phase, in which silica grain is supplied into the interior space of a silica tube having an open upper end and a closed lower end, in order to obtain an unprocessed preform, and includes a final process phase, in which the interior space of the silica tube is closed, a condition of reduced pressure is generated, the unprocessed preform is heated with a final process temperature in order to fuse the silica tube and the silica grain. According to the invention the silica grain entering the interior space is thermally treated during the preliminary process phase with an intermediate process temperature that lies under the melting point of the silica grain.

Abstract: The method for fabricating an optical fiber comprises the steps of inserting a primary optical fiber preform (11) having a first primary axis (x1) and an outer surface (111) into an overcladding tube (12) having a second primary axis (x2) and an inner surface (120), so that said outer surface and inner surface define an interior space (15); holding the primary preform (11) in a centrally inserted position within the overcladding tube (12) with said first and second primary axes (x1, x2) in substantial alignment with each other; supplying overcladding grain (13) into the interior space (15) that is limited at the lower end of the overcladding tube (12) by means of a closure (125); generating a condition of reduced pressure within the interior space (15) that is limited at the upper end of the overcladding tube (12) by means of an adjoiner (3), which holds the primary optical fiber preform (11) and the overcladding tube (12) in position; and heating the unprocessed secondary preform (1), that consists of the pr

Abstract: The present invention relates to a method and an apparatus for fabricating a preform (1,10,100) that can be used for drawing an active optical fiber (8). The present invention further relates to an active optical fiber (8), designed for amplification or attenuation purposes, drawn from said preform (1,10,100) and to an optical amplifier (600, 601) using a laser active optical fiber.

Abstract: The method for fabricating an optical fiber comprises the steps of inserting a primary optical fiber preform (11) having a first primary axis (x1) and an outer surface (111) into an overcladding tube (12) having a second primary axis (x2) and an inner surface (120), so that said outer surface and inner surface define an interior space (15); holding the primary preform (11) in a centrally inserted position within the overcladding tube (12) with said first and second primary axes (x1, x2) in substantial alignment with each other; supplying overcladding grain (13) into the interior space (15) that is limited at the lower end of the overcladding tube (12) by means of a closure (125); generating a condition of reduced pressure within the interior space (15) that is limited at the upper end of the overcladding tube (12) by means of an adjoiner (3), which holds the primary optical fiber preform (11) and the overcladding tube (12) in position; and heating the unprocessed secondary preform (1), that consists of the pr

Abstract: The method for fabricating an optical fiber comprises the steps of inserting a primary optical fiber preform (11) having a first primary axis (x1) and an outer surface (111) into an overcladding tube (12) having a second primary axis (x2) and an inner surface (120), so that said outer surface and inner surface define an interior space (15); holding the primary preform (11) in a centrally inserted position within the overcladding tube (12) with said first and second primary axes (x1, x2) in substantial alignment with each other; supplying overcladding grain (13) into the interior space (15) that is limited at the lower end of the overcladding tube (12) by means of a closure (125); generating a condition of reduced pressure within the interior space (15) that is limited at the upper end of the overcladding tube (12) by means of an adjoiner (3), which holds the primary optical fiber preform (11) and the overcladding tube (12) in position; and heating the unprocessed secondary preform (1), that consists of the pr

Abstract: An inlet arrangement for inserting a preform (3?) into a furnace (1?) for drawing a fiber (2?). The furnace includes an enclosure (4?) at the top of which there are both an opening to allow insertion of a preform which moves in translation, and a preform inlet arrangement (13?). The inlet arrangement comprises both an injector (6?) situated at the level of the opening to inject inert gas around the preform and to fill the enclosure, and at least one seal (17B) fixed above the injector and designed to allow the preform to pass therethrough, with its cylindrical main body (9?) being surrounded. The inlet arrangement further comprises an airlock (13) for closing and sealing the top of the furnace, above the injector, whether a preform is present or absent, which airlock is pressurized to prevent the surrounding air entering. The rods of the equipped preforms carry respective continuity tubes (20) of the same diameter as the bodies.

Abstract: An inlet arrangement for inserting a preform (3′) into a furnace (1′) for drawing a fiber (2′). The furnace includes an enclosure (4′) at the top of which there are both an opening to allow insertion of a preform which moves in translation, and a preform inlet arrangement (13′). The inlet arrangement comprises both an injector (6′) situated at the level of the opening to inject inert gas around the preform and to fill the enclosure, and at least one seal (17B) fixed above the injector and designed to allow the preform to pass therethrough, with its cylindrical main body (9′) being surrounded. The inlet arrangement further comprises an airlock (13) for closing and sealing the top of the furnace, above the injector, whether a preform is present or absent, which airlock is pressurized to prevent the surrounding air entering. The rods of the equipped preforms carry respective continuity tubes (20) of the same diameter as the bodies.

Abstract: An apparatus for curing a photocurable coating provided on a fiber, includes an irradiator tube having an upstream end on which an injection assembly is provided, and a downstream end on which an exhaust assembly is provided. The injection assembly receives an inert gas flow. The injection assembly includes a diffuser that splits the inert gas flow into a counter flow and a tube flow. The counter flow is directed counter to the travel direction of the fiber, and the tube flow is directed in a laminar fashion through the irradiator tube. The exhaust assembly has a vent though which the tube flow is drawn, and an air opening provided between a downstream end of the irradiator tube and the exhaust vent.

Abstract: An apparatus for curing a photocurable coating provided on a fiber, includes an irradiator tube having an upstream end on which an injection assembly is provided, and a downstream end on which an exhaust assembly is provided. The injection assembly receives an inert gas flow. The injection assembly includes a diffuser that splits the inert gas flow into a counter flow and a tube flow. The counter flow is directed counter to the travel direction of the fiber, and the tube flow is directed in a laminar fashion through the irradiator tube. The exhaust assembly has a vent though which the tube flow is drawn, and an air opening provided between a downstream end of the irradiator tube and the exhaust vent.