Method for producing an optical fibre and blank for an optical fibre

A method for the manufacture of an optical fiber by drawing from a preform with a core-clad structure or from a coaxial arrangement of several components forming a core-clad structure, in which a core cylinder is produced with a soot deposition method with the core cylinder having a core glass layer of a higher refractive index “nK” and outer diameter “dK”, which is surrounded by a first cladding glass layer of a lower refractive index “nM1” and outer diameter “dM1”, and a second cladding glass layer is applied onto the core cylinder, whereby the second cladding glass layer is provided in the form of a cladding tube produced in a separate step of the procedure, the cladding tube having a mean OH concentration of max. 1 wt-ppm, with the second cladding glass layer being applied by collapsing the cladding tube onto the core cylinder (2;

• 3), and that a core cylinder (2;
• 3) with a ratio of “dM1” to “dK” between 1 and 2.2 is used, and the core cylinder having a mean OH concentration of max. 1 wt-ppm in an area near the surface up to a depth of 10 μm, characterized in that the core cylinder (2;
• 3) is manufactured according to the outside vapor deposition method (OVD method), and that the second cladding glass layer (4) is produced with the ratio of outer diameter to inner diameter being between 1.8 and 3 and that the second cladding glass layer (4) is surrounded by at least one additional, third cladding glass layer (5).