Raman scattering spectrum analyses for fluorine-doped silica optical fibers

Abstract
Raman scattering spectra for fluorine-doped silica fibers are measured. A Raman scattering peak, assigned to be the Si–F bond in the fibers, is observed at a wave number of 930 cm−1. Heat tests in a hydrogen gas atmosphere are carried out. The result shows that the fiber loss due to the hydroxyl group, which is produced by the heat test, decreases by fluorine doping. These phenomena show that the Si–O–Si bond defects are filled with doped fluorine atoms, and oxygen atoms positioned at the defects are exchanged by the fluorine atoms.