Patent ID: 8635889

Claim:
A method for producing a bending-insensitive optical fiber, said method comprising: providing a quartz glass preform or a coaxial assembly of quartz glass components; and elongating said quartz glass preform or said coaxial assembly of quartz glass components so as to produce the optical fiber comprising a core zone of quartz glass with a refractive index n K , a cladding zone of quartz glass cladding the core zone and having a refractive index n M , and a ring zone surrounding the cladding zone, said ring zone being of a fluorine-doped quartz glass and having a refractive index n F , where n F <n M <n K , said providing including providing a substrate body in the form of a mother tube of quartz glass having an outer diameter of at least 70 mm, including forming at least part of the quartz glass of the mother tube using a soot deposition process that includes depositing SiO 2 particles so as to form a SiO 2 soot body, and producing the quartz glass of the ring zone in a plasma outside deposition process by producing, on the substrate body, a ring zone layer of the fluorine-doped quartz glass with a layer thickness of at least 1 mm and the refractive index n F being less than or equal to 1.4429, based on the D-line of a sodium vapor lamp, wherein the quartz glass of the mother tube has a refractive index equal to the refractive index n M and less than the refractive index n F of the quart glass of the ring zone laver; and wherein the ring zone layer is applied to the mother tube and the ring zone layer is elongated with the mother tube into a zone tube.