FLUORINE SOURCES FOR SINGLE-MODE FIBERS.

The possibility of using SF//6 and CF//4 as fluorine sources has been studied by utilizing the modified chemical vapor deposition method. It has been found that the refractive index change of fluorine-doped silica glasses strongly depends on the source materials and the deposition temperature. A maximum refractive index change of 0. 05 has been observed by using SF//6 as the fluorine source. No excess absorption loss resulting from the use of SF**6 in the long wavelength region has been observed in single-mode fibers with fluorine and P//2O//5-doped silica glass cladding.