(Invited) Recent Progress in VAD Fiber Fabrication Process

Since the development of the Vapor-phase Axial Deposition (VAD) process in 1977, rapid progress has been made in the improvement of transmission properties by the analysis of the above process. This paper describes the progress in the fabrication process for attaining better transmission characteristics and future aspects of this process. Specific characteristics obtained in this process are: reduction in the transmission loss of fibers by the optimal material composition and dehydration technique, the realization of less than 1 ppb of OH content, a bandwidth that now exceeds 6 GHz-km at 1.3 µm, which was attained through the analytical studies of the profile formation mechanism and the controlling of the deposition condition, and the production of long low-loss graded-index fibers.