Patent ID: 7376316

Claim:
A method of manufacturing an optical fiber preform, comprising: subjecting a starting pipe including not less than 0.1 percent by weight of chlorine to an inside vapor phase deposition so that a glass layer to be formed into a core and a glass layer to be formed into a part of a cladding are deposited inside the starting pipe, the glass layers each containing at least one of fluorine, germanium, phosphorous, and chlorine, the starting pipe being made of silica glass and having an outside diameter in the range of 20 mm to 150 mm and a wall thickness in the range of 2 mm to 8 mm, and thereby forming a pipe having a glass layer to be formed into a core; and collapsing said pipe so as to form a glass rod in which the concentration of OH groups is 10 weight ppm or less in a region from the surface of the glass rod to a depth of 1 mm therefrom.