Abstract

Phosphorus doping in vapor phase glass formation in modified chemical vapor deposition (MCVD) is investigated to facilitate understanding the cause of concentration gradients within individual MCVD layers. These inhomogeneities are evident in all MCVD preforms and fibers as slight wiggles in the deposited cladding material. Phosphorus is chosen as a representative dopant with the goal of determining the optimal process conditions to maximize incorporation or reduce the concentration gradients. Possible applications are in the fine tuning of MCVD processes to eliminate perturbations which may be the source of microbending losses and in the fabrication of gradient-index lenses by MCVD techniques. This model is also applicable to the previously demonstrated¹ modification of dopant profiles during sintering in the VAD process to achieve a more carefully controlled index profile.

© 1988 Optical Society of America