A new method fot the refractive index distribution measurement using a set of single-mode and multimode optical fibers is investigated experimentally. It is confirmed that the optical multiple reflection is neglected, and this leads the accurate measurement with high stability and easy handling.

Relative-Refractive-Index-Difference (Δ) dependence of intrinsic loss of GeO2-Doped graded index silica fibers is clarified in the practical range of 1Δ2% and λ1.5 µm. It is confirmed that the decisive factor of Δ dependence is ultraviolet absorption loss, and that the Δ dependence of scattering loss is small.

Application of liquid crystal polymer (LCP) materials, having a higher Young's modulus than usual plastic materials, to optical fiber jackets and unit central members has been investigated. Novel optical fiber units thus constructed are found to exhibit ultra low thermal expansion coefficient and no optical loss change within 6060 range. Zero thermal expansion coefficient can be achieved over the wide temperature range by suitable combination of LCP materials with high and medium Young's moduli.

Molded demountable single fiber connectors have been constructed, which contain precision balls within the plug moldings to locate the fiver and to align a pair of plugs. Transmission loss characteristics were examined and fiber placement precision investigated. The samples tested have exhibited less than 0.2 dB losses with index matching and less than 2 µm fiber displacements on an average for ordinary multimode fibers. For practical application, arbitrary diameter plugs using two sorts of balls and premolding plug ferrules were also investigated. The results exhibited high precision and low losses corresponding to the design condition. The molding procedure is simple and needs no complicated alignment mechanisms. These connectors are low in cost and possible to assemble in the field.

New splicers and connectors for multimode fibers have been fabricated. They contain precision multi-glass-rod arrangement, made by drawing, for aligning the fibers. In the multirod fabrication, the rod deformation of pyrex glass due to fusing is less than 1% in the rod array direction, in the 9001000 heating temperature range. The small deformation of 1% has no effect on splicing loss and fiber setting on the fabricated grooves. The multirod arrangement exhibits about 1 µm fabrication precision, because of the scaling down effect due to the drawing process. The splicers using a linear-multi-glass-rod arrangement exhibit 0.1 dB average splicing losses and slight loss fluctuation, less than 0.05 dB, in the 20 +60 temperature range. The connectors using a polygonal-multi-glass-rod arrangement exhibit 0.2 dB average connecting losses with index matching and 3.5 µm average off-axes. The splicers and connectors are potentially low in cost.