Low-loss silica core-borosilicate clad fiber optical waveguide

A low-loss fiber optical waveguide has been constructed having a pure fused silica core of 40-μm diameter and a chemical-vapor-deposited cladding layer of borosilicate glass 15–20 μm thick. This core-clad structure has an outer jacket of fused silica which serves to strengthen and protect the waveguide. Fabrication procedures and evaluation techniques are described. One fiber has been found to have a minimum optical attenuation of 13 dB/km at a wavelength of 0.7 μm. In the range 0.8–1.1 μm, where optical communications appear most promising, the attenuation varies between 18 and 22 dB/km with the exception of the OH absorption peak at 0.95 μm.