OPTICAL FIBER AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an optical fiber which is an optical fiber of a ring type structure obtained by adding an F element to a central core part, is stably manufacturable and has a desired refractive index profile and a method for manufacturing the same. SOLUTION: This optical fiber has the central core region 11 which consists of quartz glass and is added with an F element, a ring core region 13 which is added with GeO2 and an internal clad region 15 which is added with the F element has a buffer layer 12 which consists of non-added SiO2 or SiO2 added with either of P or Cl or both thereof or a concentration gradient region which is decreased in the concentration of GeO2 toward the boundary in a diametral direction between the central core region 11 and the ring core region 13.