PURPOSE: To efficiently manufacture a base material for an optical fiber or a rod lens by simultaneously building up glass layers on the inside and outside of a quartz glass tube by a CVD method.
CONSTITUTION: In the manufacture of a base material for an optical fiber or a rod lens, while rotating a quartz glass tube 1 around its axis, SiCl4 as a starting material for glass and GeCl4 as a dopant from a starting material system 4 are passed through the tube 1 together with oxygen as a carrier gas. At the same time, gaseous oxygen 5, gaseous hydrogen 6 and a mixture of SiCl4 as a starting material for glass and GeCl4 or the like as a dopant with a carrier gas such as Ar or He are fed from a burner 2 moving in the longitudinal direction of the tube 1. The tube 1 is heated by an oxyhydrogen flame formed with the burner 2, and glass layers A, B with the desired refractive indexes can be simultaneously formed on the inside of the tube 1 by an internal CVD method and on the outside by an external CVD method.
MURATA HIROSHI
YOSHIDA KAZUAKI
FURUKAWA ELECTRIC CO LTD
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