Abstract: A method and apparatus for forming an optical transmission element having a fiber shaped optical waveguide loosely received in a tubular jacket containing a filling material characterized by introducing a fiber into a jacket as it is being extruded at an elevated temperature, cooling the jacket and fiber to a second temperature below said elevated temperature and above the ambient temperature, coiling the cooled jacket into a coil arrangement and while coiling controlling the rate of introduction of the fiber into the jacket so that the fiber lies on the inner diameter of each radius of curvature of the coil with the amount of retardation of the introduction and the amount of the second temperature above room temperature being arranged so that upon cooling to room temperature, the fiber has the desired length relationship to the length of the jacket.