QUARTZ OPTICAL FIBER AND ITS PRODUCTION

摘要

PURPOSE:To provide a quartz optical fiber having improved mechanical strength without impairing transmission loss and a process for producing the fiber. CONSTITUTION:This quartz optical fiber has an internal clad 2 on the outer periphery of a core 1 and an outer clad 3 on the outer periphery of the internal clad 2. The softening temp. of the outer clad 3 is higher than the softening temp. of the core 1 or the inner clad 2. The outer periphery of the outer clad 3 is provided with a glass layer 4 having the softening temp. lower than the softening temp. of the outer clad 3. Since the glass layer 4 having the softening temp. lower than the softening temp. of the outer clad 3 exists on the outer periphery of the outer clad 3, only the surface has nearly a molten state even if the fiber is drawn at a low drawing temp. The surface flaws of the optical fiber generated in a preform stage are drastically decreased.