A method of manufacturing an optical waveguide in a polymer

The invention relates to a method for producing an optical waveguide, in particular a single-mode optical fiber, in a polymer, wherein a first laser beam of a first wavelength in the polymer is focused at a focus point, wherein a second laser beam, in particular the first wavelength, in the polymer in the focal point is focused and intersects the first laser beam, so that the refractive index of the polymer changes in an area around the focal point or increased, and wherein the focal point along a trajectory through the polymer is moved.