A preform process permitting 80-km drawable-fiber length has been developed. Important aspects of the preform deposition and collapsing are discussed. High-quality preforms have been manufactured with two types of synthetic tubes. For single-mode fibers having 9.0-μm mode-field diameter with slightly depressed-index cladding, the median attenuations on a production basis are better than 0.335 and 0.20 dB/km at 1310 and 1550-nm wavelengths, respectively.
Jouko A. Kurki,
"Large modified chemical vapor deposition preform optimization," Optical Engineering 34(9), (1 September 1995). https://doi.org/10.1117/12.208084