The development of low loss, high silica optical fibers over the last few years has required the development of high temperature heat sources, over 2000°C, for the drawing of the fiber. Of the possible heat sources the oxy- hydrogen torch, the CO2 laser and a few furnaces have been employed for drawing the high silica fibers. The torch method, while inexpensive, possesses control and contamination difficulties. High temperature furnaces provide high thermal inertia, high stability, and radially symmetric heating. Most furnaces, however, possess graphite or metallic heating elements which requires flowing protective atmospheres during operation and as a result have limited element life and show some degree of contamination in the furnace atmosphere. The CO2 laser provides the cleanest drawing atmosphere, but requires unique optical designs to radially distribute the energy for drawing and they are limited in power.

© 1977 Optical Society of America

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