Raymond Edward Jaeger

Borosilicate glasses for fiber optical waveguides

Abstract Of the existing optical glasses, pure fused silica is known to have the lowest optical attenuation in the red and near infrared portion of the spectrum where optical communications appears most promising. However, to approach the low attenuations afforded by pure fused silica in a waveguide structure requires that a core of fused silica be clad with a glass of slightly lower index refraction. This paper describes an investigation of the binary borosilicate glass system which has led to the realization of a promising cladding material for pure fused silica core fibers.

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.

Epoxy‐acrylate‐coated fused silica fibers with tensile strengths ≳500 ksi (3.5 GN/m2) in 1‐km gauge lengths

Laser‐drawn epoxy‐acrylate‐coated fused silica fibers (∼110 μm fiber diameter) have been produced with high and exceptionally uniform strength. When tested in 20‐μm lengths, they show a single‐moded Weibull distribution, (m∼25), a median tensile strength Sm of 750 ksi (5.25 GN/m2), and a coefficient of variation (ν) of about 0.04. Using the previously justified ’’weakest link’’ model, this predicts Sm∼600 ksi (4.2 GN/m2) for l‐km gauge lengths. The measured strength of a 1680‐m‐long fiber (i.e., the minimum strength found in testing 84 20‐m lengths) is 620 ksi (4.35 GN/m2). The capability of drawing kilometer lengths of fibers with strengths of this magnitude and uniformity is extremely important for the production of optical fiber cables.

Binary SiO2–B2O3 glass system: Refractive index behavior and energy gap considerations

A recent investigation of the binary borosilicate glass system has led to the realization of a useful cladding material for pure fused silica core fiber optical waveguides. The feature which makes the borosilicate glass useful is that its index of refraction is sufficiently less than that of pure fused silica to allow light guidance in silica core‐borosilicate clad fibers. The previous work offered no explanation for the observed but unexpected behavior of the borosilicate refractive index. Continued studies of this glass system have now led to a quantative explanation of the refractive index behavior. Two theoretical approaches are discussed. One is based on the Sellmeier dispersion model and the other on a molar refractivity analysis. The main quantities of interest turn out to be density, composition, structure, and ionicity. An important prediction based on this work is that properly quenched borosilicate glass can have a refractive index even lower than previously observed. This prediction was subseq...