PURPOSE: To provide a method for producing an optical fiber homogeneously mixed with a metal such as a rare earth metal and with Al.
CONSTITUTION: A method for producing an optical fiber base material comprises a retaining part-forming process for forming a retaining part for an additive solution in a starting quartz tube, a soot-depositing process for depositing soot in the retaining part, an additive-doping process for doping the soot-deposited part with an additive, and finally a collapsing process. Since the rare earth metal and the Al can be added to the optical fiber base material in high concentrations, the wavelength-gain characteristics of the produced optical fiber are largely improved. Since the Al is also added in a high concentration, a co-operative.up.conversion effect is reduced in a light-amplifier using the optical fiber.
SAKAI TETSUYA
WADA AKIRA
YAMAUCHI RYOZO
