Glass composition, optical fiber made of same, and method for preparing glasses

摘要

A glass composition comprises an oxyfluoride glass comprising silicon, a divalent metal, a monovalent metal, oxygen, and fluorine, satisfying requirements: (1) the silicon is present in an amount of 40% or more and 75% or less based on total number of cations; (2) the divalent metal is present in an amount of 30% or less based on total number of cations; (3) the monovalent metal is present in an amount of 18% ore more and 60% or less based on total number of cations; and (4) the fluorine is present in an amount of below 20% based on total amount of anions. An optical fiber comprises a clad made of the glass composition and a core made of a silicate glass comprising silicon dioxide, a divalent metal compound, and a monovalent metal compound in which (9) the clad glass contains more SiO2 than the core or (10) the clad glass contains fluoride(s) of the divalent metal and/or the monovalent metal.