The present invention relates to a method for manufacturing a preform of silica for optical fiber production, as well as to a method for the production of optical fibers comprising a step of drawing the optical fiber from such a preform of silica, the method comprising a step of vaporization of a siloxane feedstock added with a compound having the following formula (I): wherein R, R and R, equal or different each other, are an alkyl group having from 1 to 5 carbon atoms, and A is a saturated or unsaturated chain of atoms selected from the group consisting of carbon atom, nitrogen atom, and oxygen atom, said chain A forming with the nitrogen atom linked thereto a saturated, unsaturated or aromatic heterocyclic moiety.

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An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and a inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

Known heating burners for producing a welded joint between components of quartz glass include a burner head in which at least one burner nozzle is formed, a burner-head cooling system for the temperature control of the burner head and a supply line connected to the burner nozzle for a fuel gas. Starting from this, to modify a heating burner in such a way that impurities in the weld seam between quartz-glass components to be connected are largely avoided, it is suggested that the burner head should include a base body of silver or of a silver-based alloy.

A method for adjusting an etchability of a first borosilicate glass by heating the first borosilicate glass; combining the first borosilicate glass with a second borosilicate glass to form a composite; and etching the composite with an etchant. A material having a protrusive phase and a recessive phase, where the protrusive phase protrudes from the recessive phase to form a plurality of nanoscale surface features, and where the protrusive phase and the recessive phase have the same composition.

A multicore fiber is provided. The multicore fiber includes a plurality of cores spaced apart from one another, and a cladding surrounding the plurality of cores and defining a substantially rectangular or cross-sectional shape having four corners. Each corner has a radius of curvature of less than 1000 microns. The multicore fiber may be drawn from a preform in a circular draw furnace in which a ratio of a maximum cross-sectional dimension of the preform to an inside diameter of the preform to an inside diameter of the draw furnace is greater than 0.60. The multicore fiber may have maxima reference surface.

The invention relates to a method of manufacturing an active optical fiber having a cladding and a doped core, as well as the active optical fiber equipped with the cladding and the doped core. The active optical fiber according to the invention is adapted to conduct and generate radiation having a wavelength and is provided with a cladding and a core containing at least one active dopant, characterized in that the core comprises elongate elements made of a first type of glass having a first refractive index n.sub.1 and elongate elements of a second type of glass having a second refractive index n.sub.2, oriented along the optical fiber and forming a compact bundle, wherein transverse dimensions of the elongate core elements are smaller than of the wavelength . Such optical fibers are used in laser generation and in amplification techniques.

In one embodiment, a chalcogenide glass optical fiber is produced by forming a billet including a chalcogenide glass mass and a polymer mass in a stacked configuration, heating the billet to a temperature below the melting point of the chalcogenide glass, extruding the billet in the ambient environment to form a preform rod having a chalcogenide glass core and a polymer jacket, and drawing the preform rod.

A rod bundle includes a core-clad rod that includes a core rod and a cladding layer that covers the core rod, a plurality of first filling rods disposed around the core-clad rod to be in contact with the core-clad rod, and two second filling rods that are disposed opposite to each other and interposing the core-clad rod therebetween to be distant from the core-clad rod and form first spaces with the core-clad rod. The rod bundle also includes a pair of second spaces that are next to the core-clad rod are formed to interpose the core-clad rod therebetween in a direction perpendicular to a direction in which the two second filling rods are opposite to each other and, in a transverse plane, an area of each of the first spaces is more than an area of each of second spaces.

The invention relates to a method of manufacturing an active optical fibre having a cladding and a doped core, as well as the active optical fibre equipped with the cladding and the doped core. The active optical fibre according to the invention is adapted to conduct and generate radiation having a wavelength and is provided with a cladding and a core containing at least one active dopant, characterised in that the core comprises elongate elements made of a first type of glass having a first refractive index n.sub.1 and elongate elements of a second type of glass having a second refractive index n.sub.2, oriented along the optical fibre and forming a compact bundle, wherein transverse dimensions of the elongate core elements are smaller than of the wavelength . Such optical fibres are used in laser generation and in amplification techniques.

A method for adjusting an etchability of a first borosilicate glass by heating the first borosilicate glass; combining the first borosilicate glass with a second borosilicate glass to form a composite; and etching the composite with an etchant. A material having a protrusive phase and a recessive phase, where the protrusive phase protrudes from the recessive phase to form a plurality of nanoscale surface features, and where the protrusive phase and the recessive phase have the same composition.