Dispersion-shifted fibers can be made by either inside vapor deposition (AT&T, BTRL) or the outside process (Corning, NTT). To reduce the excess loss related to higher Ge content in the central core, depressed-cladding structures1 or the double-core profile have been advocated. The present work points out that improvement of fiber drawing conditions of classical matched-cladding triangular core-index profile preforms can also give very low-loss 1.55-μm dispersion-shifted fibers. Low-temperature fiber drawing has already been reported as appropriate for higher Ge content.2 Evidence is given here, for the first time to our knowledge, that such drawing conditions lead to a modification of the index profile generated by internal fiber stress.
© 1988 Optical Society of AmericaPDF Article