MOLD FOR PRODUCING PREFORM FOR OPTICAL FIBER AND PRODUCTION OF PREFORM FOR OPTICAL FIBER USING THE SAME MOLD

摘要

PURPOSE: To obtain a preform capable of providing an optical fiber having an ultralow loss by successively casting a clad glass melt and a core glass melt into a hollow part of a mold having the hollow part and a hollow bottom having a larger diameter than that of the hollow part. ;CONSTITUTION: A mold 1 for producing a preform for an optical fiber equipped with a hollow part 1A for forming the preform for the optical fiber having a uniform diameter or a diameter increasing from the upper to the lower parts and a hollow bottom connecting to the hollow part 1A in the lower part thereof and further a larger diameter of the hollow bottom than that of the lower end of the hollow part 1A is prepared and a clad glass melt 2 is then cast into the hollow part 1A of the mold 1. A core glass melt 4 is then cast onto the clad glass melt 2 to make the core glass melt 4 flow into the hollow bottom in the central part of the clad glass melt 2. The resultant casting is then cooled to afford the preform for the optical fiber.;COPYRIGHT: (C)1996,JPO