The invention relates to a method for producing glass fibers that laterally emit light and to glass fibers produced according to said method. The problem of providing a method that relies on standard available glass components, thus making possible an economical production method that allows a glass fiber to be produced which emits laterally and, in an optically active manner, spectrally shifts, scatters and/or filters light coupled into the fiber when said light exits through the fiber cladding, is solved in that, first, glass tubes (7) and glass rods (5) of identical chemical composition and identical optical refractive index are selected, then first the glass rod (5) is coated completely or over parts of its outer periphery with a vitrifiable material mixture containing optically active substances, in the liquid phase, and the glass rod (5) coated in such a way with this coating (6) after said coating has been dried or consolidated is brought into the glass tube (7) and both are jointly drawn, under the application of heat, to form a glass fiber in a known way.

The method for manufacturing an optical fiber preform, the method includes: doping at least one element selected from an alkali metal group into a first glass pipe; collapsing the first glass pipe, thereby obtaining a glass rod; and performing at least one rod-in-collapse. The collapsing and the performing the at least one rod-in-collapse are performed while traversing an external heat source in a first direction from a first end toward a second end of the glass rod or in a second direction from the second end toward the first end. In the collapsing and the performing the at least one rod-in-collapse, a difference between the number of times of the traversing in the first direction and the number of times of the traversing in the second direction is 1 or less.