Abstract: Optical fibers are produced by means of a direct sleeving technique that allows the sintering and collapsing of the outer jacket tube onto the inner core rod to be achieved directly during the drawing phase of optical fiber manufacture. In the course of the optical fiber manufacturing process, either a mechanical guide holding a sleeving tube concentrically around an annular gap and core rod or a preform having an enclosed annular gap/cavity are mounted in a drawing tower. A vacuum may be maintained in the annular gap/cavity of this assembly. A heat source is then applied to one end of the preform/assembly such that the extreme end of the tube is collapsed onto the core as fiber is drawn in a controlled manner. This single-step process allows to speed up the sleeving process, without introducing possible asymetries in the final preform and in the fibers drawn therefrom.