PRODUCTION OF PARENT MATERIAL FOR OPTICAL FIBER

摘要

PURPOSE:A glass rod with axis-symmetrical distribution of a refractive index is inserted into a glass tube with concentrical distribution of refractive index in the diameter direction, they are integrated by heating to produce a glass parent material for single mode fiber having zero-dispersion wave-length in a specific range. CONSTITUTION:A glass cylinder with axia-symmetrical distribution of refractive index around the axis is made by the VAD process. Separately, a glass rod having the axis-symmetrical distribution of refractive index for the core and the first clad is formed by the CVD process and drawn. The glass rod reduced in its diameter is inserted into the glass tube and they are integrated by heating. The process according to the present invention permits the production of a glass parent material for a single mode fiber with such a structure as its distribu tion of refractive index has a complicated form along the diameter direction and several maximal and minimal points. The resultant parent material has a refractive index distribution shown in the figures a through c.