Process for producing a rare-earth optical single-mode fiber doped and rare-earth optical single-mode fiber doped

摘要

The process of fabricating a multi-sheath optical fiber with doped core (1), comprises depositing a first sheath (6) layer inside a first carrier tube, depositing a second silicon porous layer inside the first carrier tube, filling the silicon porous layer by a solution comprising rare earth salts to obtain a rare earth metal doped silicon layer, glassifying the rare earth metal doped silicon layer, shrinking the tube for forming a bar comprising a plane core doped with rare earth metals and surrounding the first sheath layer, and removing the outer side of the first carrier tube. The process of fabricating a multi-sheath optical fiber with doped core (1), comprises depositing a first sheath (6) layer inside a first carrier tube, depositing a second silicon porous layer inside the first carrier tube, filling the silicon porous layer by a solution comprising rare earth salts to obtain a rare earth metal doped silicon layer, glassifying the rare earth metal doped silicon layer, shrinking the tube for forming a bar comprising a plane core doped with rare earth metals and surrounding the first sheath layer, removing the outer side of the first carrier tube, depositing another sheath layer, inside another carrier tube, made of a material having a refractive index lower than refractive index of doped core, coupling the doped core with the carrier tube, removing the outer side of the carrier tube by stopping the deposition of cladding in the layer within the carrier tube, forming a stack of sheath layers surrounding the core in one section of the first sheath layer, coupling a preform with a sleeve having an effective refractive index lower than the first sheath to form a second sheath (7), and performing fusion and stretching of the preform for obtaining a multi-sheath fiber (20) with single-mode doped core and multimode sheath guide. The difference between the refractive index of the core of the fiber and refractive index of the core of the first sheath is 0.5-5x 10 -3. The refractive index of the first sheath of the fiber is greater than refractive index of the pure silica of 5x 10 -3. The material of the first sheath is silica doped with germanium. The coupler for forming the second sheath is a tube made of non-doped silica, and comprises capillaries for forming an air-cladding type fiber. The process further comprises making a hole in the first sheath of the final preform, which extends longitudinally relative to the axis of the preform, and inserting stress rods, into the holes, made of a material having a thermal coefficient of expansion different from the first sheath. An independent claim is included for a multi-sheath optical fiber with doped core for fiber amplifier or laser.