Abstract

A process that combined axial and radial deposition was first investigated by Powers.¹ In his approach, a soot preform had its central section made by axial deposition, and, at the same time, outer regions of the preform were deposited radially by oscillating burners. In the manufacture of single-mode fibers by the VAD process, the best control of refractive index and dimensions has been obtained with soot diameters of the core region of ~20 mm. This then necessitates that the soot diameter of preforms made by a single-step hybrid process be ~280 mm for single-mode fibers with a cutoff wavelength at 1.2 μm. This being beyond today’s state of the art, we decided to develop a process with two sequential deposition steps. The process steps of this hybrid process are shown below along with those of the conventional VAD process:

© 1985 Optical Society of America