Title: Optical fibre covered with amorphous boron protective layer and method of depositing such layer
Application Number: 95190804 Application Date: 1995.08.23
Publication Number: 1134141 Publication Date: 1996.10.22
Approval Pub. Date: 2000.05.10 Granted Pub. Date: 2000.05.10
International Classifi-cation: C03C25/10;G02B6/44
Applicant(s) Name: Alcatel Fibres Optiques Address:
Inventor(s) Name: Claude Brehm;Lionel Vandenbulcke;Jean-Yves Boniort
Attorney & Agent: DU RIXIN
Abstract:
    Optical fiber comprising an optical core surrounded by an optical sheath, both of a silica-based material, and a protective amorphous boron layer. The invention is characterized in that the protective boron layer is deposited on the non-crystalline carbon layer, which is directly deposited on the optical sheath. The device (10) comprises, aligned with one another within a vertical fiber drawing plant: a fiber drawing oven (11) in which is drawn, in a conventional and known manner, a preformed fiber (12) with an optical core (not shown) having the same composition as and a diameter greater than the core (2), enclosed in an optical sheath (not shown) having the same composition as and a thickness greater than the optical sheath (3), the diameter ratio of the optical sheath to the optical core of the preformed fiber (12) being the same as the diameter ratio of the optical sheath (3) and the optical core (2); a reactor (14) for depositing the non-crystalline carbon layer (4) on the bare optical fiber (13); a reactor (15) for depositing the boron amorphous layer (5); means (16) for controlling the diameter of the fiber at the reactor outlet (15); resin-coating means (17) for forming the resin layer (6) on the boron layer (5); a device (18) for polymerizing, with ultraviolet radiation, the resin layer (6); means (19) for controlling the final diameter of the fiber (1) obtained; a reel (20) for winding the finished fiber (1). The boron layer is applied to the carbon-coated optical fiber through the reduction of boron halide, for exemple, gaseous boron chloride, with gaseous hydrogen, based on the following equation: 2BCl3 3H2 } 2B 6HCl. The boron coating is hence applied by chemical vapour deposition. The reduction takes place at a temperature of about 1150 DEG C, the boron chloride/hydrogen molar concentration ratio being close to 1/4.
Time: 12
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